Environmental Factors Associated with Breast Cancer

A recent report says that "Lifestyle Changes Prevent One-Third of Cancers", and that fewer than 10 percent of breast cancer cases are inherited (33rd Annual San Antonio Breast Cancer Symposium, 12/7/2011).

Anything that increases a woman's exposure to estrogen also increases her risk for breast cancer, a disease that affects one in eight women:

• being overweight: Full fat cells make estrogen, so overweight women have more estrogen
• not exercising: lack of exercise increases risk for obesity
• drinking alcohol
• taking birth control pills
• taking estrogen and progesterone pills at any age
• starting periods before age 11
• starting menopause after age 55
• never being pregnant (thus more menstrual cycles)
• never breast feeding

Radiation from too many medical tests also increases breast cancer risk. Three abdominal CT scans give as much radiation as atomic bomb survivors received. Possible, but unproven, causes of breast cancer include: smoking, second-hand smoke, nighttime shift work, exposure to benzene and other chemicals, or to BPA and certain other plastics ingredients.

There is no evidence that breast cancer is caused by hair dyes or by radiation from cellphones, microwaves or other electronic gadgets.

WHY DOCTORS PRESCRIBE PROGESTERONE: Taking progesterone and estrogen markedly increases breast cancer risk. Estrogen stimulates the inner lining of the uterus to grow, and uncontrolled growth is cancer. Taking estrogen can cause uterine cancer, while progesterone stops estrogen from stimulating the uterus. So, to prevent uterine cancer, doctors usually prescribe progesterone with estrogen to any woman who still has a uterus. However, taking both estrogen and progesterone increases breast cancer risk. Many doctors now recommend no hormone therapy for women at menopause.

Why Three out of Four Athletes Take Caffeine Before Competition

In January 2004, the World Anti-Doping Agency removed caffeine from its prohibited drug list to allow athletes to take coffee, tea, chocolate, cocoa, guarana, cola drinks, energy drinks and so forth. Researchers have now measured the caffeine concentration in 20,686 urine samples obtained for doping control from 2004 to 2008. They found that 75 percent of athletes in official national and international competitions had consumed caffeine before or during competition (Appl Physiol Nutr Metab, Aug 2011;36(4):555-61). As expected, athletes in endurance sports (triathlon, cycling, and rowing) had the highest urine concentrations of caffeine. Gymnasts had the lowest urine caffeine concentration. Athletes older than 30 had higher levels of caffeine in their urine than those younger than 20. Males and females had the same urine concentrations.

HOW CAFFEINE INCREASES ENDURANCE: The limiting factor to how fast you can move during a race is the amount of oxygen that you can take in and use. Since sugar requires less oxygen than fat to power your muscles, you want to get sugar into your muscles as quickly as possible. Anything that increases the amount of sugar that can be absorbed from your intestines into your bloodstream will help you ride or run faster and longer.

When you exercise, caffeine can increase endurance by increasing the absorption of sugar from your intestines (Medicine & Science in Sports & Exercise, July, 2010) and by increasing the uptake of sugar by your exercising muscles by as much as 26 percent (Journal of Applied Physiology, June 2006).

Caffeine helps athletes run faster in both short and long-distance races. In short races, it makes athletes faster by causing the brain to send messages along nerves to cause a greater percentage of muscle fibers to contract at the same time. In longer races, it delays fatigue by preserving stored muscle sugar. Muscles get their energy from sugar and fat in the bloodstream, and from sugar, fat and protein stored in the muscles. When muscles run out of their stored sugar, they hurt and become more difficult to coordinate. Caffeine causes muscles to burn more fat, thus sparing stored muscle sugar to delay fatigue.

HOW MUCH DO YOU NEED? Most research shows that it doesn't take much more than one or two soft drinks to increase endurance. Caffeine loses its beneficial effects with repeated exposure, so athletes who want to gain maximum advantage from caffeine during competition should avoid drinking caffeinated beverages when they are not competing.

HOW MUCH IS SAFE? Nobody really knows how much caffeine you can take in without harming yourself. At rest, caffeine is a diuretic, but during exercise it does not increase urination. Caffeine is a potent stimulant that can cause irregular heartbeats and raise blood pressure.

RESTRICT CAFFEINE WHEN NOT COMPETING: Caffeine increases sugar absorption from the gut. Taking caffeine when you eat carbohydrate-containing foods can double your rise in blood sugar (Journal of Caffeine Research, April 16, 2011). Since more than 35 percent of North Americans will become diabetic and have high rises in blood sugar levels after meals, most people should not take caffeinated drinks with meals that contain carbohydrates: bread, spaghetti, or sugared foods and drinks. If you are already diabetic, your blood sugar levels rise even higher and you suffer cell damage. This cell damage causes all of the horrible side effects of diabetes: blindness, deafness, heart attacks, strokes and so forth.

Sarcopenia: Muscle Loss with Aging

Competitive masters athletes, 40 to 81 years old, who trained four to five times per week did not lose any muscle size or significant strength with aging (The Physician and Sportsmedicine, October 2011;39(3):172-8). This shows that loss of muscle size and strength in older people is caused by lack of exercise, not just with aging. The athletes did gain fat in spite of exercising. Those in their 70s had almost as much strength and thigh muscle size as those in their 40s.

MOST PEOPLE LOSE MUSCLE: Recent studies show that after age 40, men lose more than eight percent of their muscle size each decade, and this loss of muscle increases after age 70. The people who lose the most muscle are usually the ones who die earliest. They are also most at risk for falls and broken bones.

HOW EXERCISE PREVENTS MUSCLE LOSS WITH AGING: Muscles are made up of thousands of individual muscle fibers. Each muscle fiber is innervated by a single nerve. With aging, humans lose the nerves that innervate muscle fibers, and with each nerve loss, they lose the associated muscle fiber so muscles become smaller. We used to think this happens because of aging. However, this new study and others show that lifelong competitive athletes do not lose the nerves that innervate their muscles with aging. They retain the nerves and therefore retain most of the muscle fibers that they would have lost if they were inactive.

MESSAGE: If you exercise regularly, continue to do so. If you don't, check with your doctor and then get instructions on how to start an exercise program.

The Only Mineral Needed by Exercisers

People who are serious exercisers can be harmed by the broad recommendations for all Americans to restrict salt intake. It is true that excess salt intake can cause high blood pressure, but heavy exercise usually helps to protect people from salt causing high blood pressure. The minimum salt requirement is 1,500 mg (1 teaspoon) of sodium a day. The average North American is told not to exceed 2,300 mg per day, but he ingests too much salt, between 3,100 and 4,700 mg of sodium per day.

FITNESS DOES NOT REDUCE SALT LOSS: This month a study from Spain shows that being fit does not reduce the concentration of salt in sweat (European Journal of Applied Physiology, November 2011). A person who exercises in the heat can lose far more than 4000 mg of salt. So in spite of the fact that most serious exercisers get a lot of salt from the massive amounts of foods that they eat, they can still become salt deficient.

SYMPTOMS OF SALT DEFICIENCY: If you are a serious exerciser and you suddenly are not recovering from your workouts as fast as you usually do, a common cause is loss of salt. Symptoms of salt deficiency include muscle weakness, soreness and cramps, loss of strength and tiredness. Get a blood test for sodium on the day after a hard workout. If your blood sodium is below 132 mmol/L, you need more salt.

SALT IS NECESSARY FOR SERIOUS EXERCISERS: In 1942 the US government commissioned James Gamble of Harvard Medical School to set mineral requirements for soldiers fighting in the Pacific. He showed that sodium (table salt) is the only mineral that needed to be replaced. Potassium, magnesium, calcium and the trace minerals were not significant. To this day, nobody has improved on his data and recommendations.

HOW SALT DEFICIENCY HAMPERS PERFORMANCE: Not taking in salt when you exercise for more than two hours can prevent you from retaining the water that you drink. It can also block thirst, so you may not know that you are dehydrated. Thirst is a late sign of dehydration. You lose water during exercise primarily through sweating, and sweat contains a far lower concentration of salt than blood. So during exercise, you lose far more water than salt, causing the concentration of salt in the blood to rise. You will not feel thirsty until the concentration of salt in the blood rises high enough to trip off thirst osmoreceptors in your brain, and it takes a loss of two to four pints of fluid to do that.

SALT BEFORE COMPETITION: Taking salt just before competition improves performance (Medicine and Science in Sports and Exercise, January 2007; Clinical Journal of Sport Medicine, January 2007). Athletes who took extra salt had larger blood volume and greater endurance. Salt makes you thirsty earlier so you drink more, and salt in your body holds water so you have more water available to meet your needs.

ENDURANCE EVENTS LASTING LONGER THAN FOUR HOURS: You can keep yourself fresh during extended exercise by eating foods with salt and drinking frequently, before you feel hungry or thirsty. Once you are weakened by loss of fluid or salt, it becomes very difficult to regain your strength. Commercial sports drinks help increase endurance with their caffeine, sugar, salt, and to a lesser degree, protein content. It is unlikely that any other component improves performance (The Physician and Sportsmedicine, April 2010).

MOST EXERCISERS DO NOT SUFFER FROM SALT DEFICIENCY: The North American diet contains up to 10 times your minimal salt requirements. Salt is added to almost all prepared foods, so if you doubled or tripled your salt losses through sweating, you would still not be deficient because you are already taking in far more salt than you need.

EXERCISE CAN PREVENT RISE IN BLOOD PRESSURE FROM SALT: People who exercise are far less likely to suffer high blood pressure from eating food with excess salt intake (presented at the American Heart Association Scientific Sessions, March 2011). High blood pressure increases risk for heart attacks, strokes, and kidney damage. Many middle-aged people who start an exercise program lose their tendency to develop high blood pressure when they take in extra salt (Journal of Human Hypertension, May 2006).

If you are concerned about your blood pressure, you can buy an inexpensive wrist cuff and check your systolic blood pressure at bedtime. If it is below 120, you probably do not need to restrict salt.

Exercise Increases Mitochondria in Brain Cells

Exercise increases the size and number of mitochondria in the brains of mice (American Journal of Physiology, September 2011). The mice ran on a treadmill for an hour a day, six days a week, for eight weeks.

This could explain how exercise improves memory, treats depression, and makes people feel better and helps them to think more clearly. Until now, the leading theory to explain how exercise improves memory and treats depression was that exercise causes the brain to release endorphins, morphine-like compounds that can improve mood (Journal of Applied Physiology May 1982). However, endorphins would not explain the improvement in memory and brain function associated with a regular exercise program.

Mitochondria are tiny chambers in cells that turn food into energy more efficiently than any other process in your body. Scientists have known for years that exercise enlarges and increases the number of mitochondria in muscle cells, to increase strength, speed and endurance; but this is the first research paper to offer a plausible explanation why exercise improves memory and relieves depression.

The increase in brain mitochondria could also explain how training for sports increases endurance by making the brain resistant to fatigue. It also could explain how exercise treats mental disorders, delays aging, and improves certain types of nerve damage.

Chocolate Increases Endurance

A recent symposium at the American College of Sports Medicine 58th Annual Meeting June 2, 2011 and other recent studies show that chocolate improves endurance training in mice and humans. Taking small amounts of a chocolate extract, called epicatechin, twice a day for two weeks shortened recovery from intense exercise and increased endurance in mice (Journal of Physiology, July 25, 2011). Drinking chocolate milk after all- out exercising helped athletes recover faster and cycle faster afterwards (Journal of Strength Conditioning Research, May 2011).

These studies do not encourage you to take chocolate just before competitions. They show that chocolate helps you to recover faster from hard exercise, and that you may benefit from taking small amounts of chocolate daily during hard training. All athletic training is done by taking a harder workout on one day, feeling sore on the next and taking easier workouts for as many days as it takes for the soreness to go away. If you can recover faster, you can do more intense training and be a better athlete.

Your body requires oxygen to convert food to energy to power your muscles during exercise. The limiting factor to how fast you can run or cycle, and how much force your muscles can generate, is the time it takes to move oxygen from your lungs into your muscles. The aim of all athletic training is to increase your body's ability to convert food to energy with the least amount of oxygen. Anything that increases oxygen supply or decreases oxygen needs will make you faster and stronger.

Your muscles convert food to energy primarily in your mitochondria, small chambers numbering from a few to thousands inside your muscles. Anything that grows new mitochondria or enlarges existing ones will make you faster and stronger. The cocoa bean contains chemicals called epicatechins that stimulate your muscles to grow and produce mitochondria. It takes only small amounts, taken regularly, to do this.

However, pure chocolate is very bitter, so manufacturers add huge amounts of sugar and saturated fats that should not be taken when you are not exercising. Eating refined sugar when you are not exercising causes a high rise in blood sugar that can damage every cell in your body and saturated fats from animals block insulin receptors to prevent insulin from clearing sugar from your bloodstream to raise blood sugar levels even higher.

• You can eat small amounts of sweetened chocolate when you are exercising.

• You should not eat sweetened chocolate when you are not exercising.

• You can eat chocolate every day that you exercise, particularly on your intense exercise days.

• You should take only small amounts as more is not more effective in hastening recovery. A reasonable daily amount would be about five grams of dark chocolate (1/6th of an ounce) per day.

Everyone Should Train like an Athlete

All exercisers should follow the principles of training used by competitive athletes. You will gain far more health benefits from intense exercise than from more casual exercise, and you will gain more strength and muscle growth. Athletes do not do the same workouts every day. If they did, they would not gain the increased strength, speed and endurance that are necessary for competition. They take an intense workout in which they feel a deep burning in their muscles, feel sore on the next day, and take lighter workouts until the muscle soreness goes away. Then they take their next intense workout.

THE FIRST PRINCIPLE OF TRAINING - BACKGROUND BEFORE PEAKING: Never try to exercise at an intense pace when you start a new program. For example, if you are starting a stationary bicycle program, ride at a very slow pace every day until your muscles start to feel sore or tight and then stop. In the first six weeks, limit your workouts to no longer than a half hour. Only after you can exercise at a casual pace for 30 minutes every day should you try to increase the intensity of your workouts. You may also want to check with your doctor before you start exercising intensely. Intense exercise can kill people who have blocked arteries leading to their hearts, and many people do not know that they have this condition until it is too late. Even regular exercisers can suffer from blocked arteries and not know it.

INTENSE WORKOUTS: Athletes divide their intense workouts into periods of *sustained effort, *short intervals, *long intervals, and *combinations of these variations. If you are not competing in athletic events, you only need to do short intervals.

SHORT INTERVALS: A short interval takes less than 30 seconds because an athlete does not accumulate significant amounts of lactic acid in less than that time. Muscle burning is caused by increased acidity in the muscle caused by lactic acid accumulation.

An athlete can do a very large number of repeat short intervals, often 100 or more in a single workout. A top runner will run a large series of short runs up to 220 yards. Cyclists often use a clock. In short intervals, athletes get out of the burn soon after they feel it.

LONG INTERVALS; Long intervals usually last two minutes or more, and build up so much lactic acid in the bloodstream that a top athlete can only do a few of them in a workout. A runner may run four to eight half-mile repeats. Cyclists may push their intervals between lamp posts or use some other measure of fixed distance of all-out riding. Long intervals are done with such intensity that the athlete is short of breath and feels intense muscle burning during each interval.

INTENSE CONTINUOUS WORKOUTS: Cyclists often use sustained workouts as the basis of their training regimens. They pick up the pace and as soon as they start to feel the burning in their muscles, they let up on the pressure, slow down, and the burning goes away. Almost immediately afterwards, they start to pick up the pace and again back off as soon as they feel the burning. Getting out of the burn as soon as it occurs allows a cyclist to take this type of intense workout for many hours.

INCREASED STRENGTH COMES FROM MUSCLE DAMAGE: The soreness that you feel usually 8 to 24 hours after an intense workout is called Delayed Onset Muscle Soreness (DOMS). DOMS is caused by muscle damage itself. Biopsies show bleeding into the muscles fibers, and disruption of the fibers and the Z- bands that hold the muscle filaments together as they slide by each other. If you don't suffer muscle damage, you do not gain significant muscle growth.

MUSCLE BURNING DURING INTENSE EXERCISE: Muscle burning during exercise means that you are applying enough force on your muscles to pull the fibers apart and damage them. However, the longer you stay in the burn, the longer it takes for the muscles to heal. Most athletes do some form of interval training that takes them out of the burn soon after their muscles start to burn.

The burning feeling in muscles that is transmitted back to your brain is actually caused by the increased acidity brought on by a buildup of lactic acid in muscles. Muscle damage is caused by the pressure on the muscles from hitting the ground with your foot during running, or pressing very hard on your pedals, and has nothing to do with excessive buildup of lactic acid. It is caused by excessive force on muscles during intense exercise. Lactic acid starts being cleared from muscles within seconds of stopping exercise. Furthermore, lactic acid is the most efficient muscle fuel, since it requires less oxygen than any other source of energy.

Athletes exercise intensely until they feel a deep burning in their muscles and then let up on the pressure. The burning usually goes away almost immediately. Then they pick up the pace to increase the pressure on their muscles to cause the burning to return. They stop the interval workout when their muscles start to stiffen and hurt.

ACTIVE RECOVERY, NOT PASSIVE: On the day after an intense workout, the athlete's muscles are supposed to feel sore. If he takes off completely, he may recover faster, but he will never reach his potential in competition. Active recovery, in which a person exercises at reduced intensity, makes the muscles more fibrous and resistant to damage during hard workouts. This allows the athlete to take more intense workouts on his hard days and makes him a better athlete. He can compete only as fast as he moves on his hard days.

A TRAINING PROGRAM FOR YOU: Set up your program so that you plan to exercise faster on three days a week, never on consecutive days. Plan to exercise at very low intensity on your four recovery days. For example Tuesdays, Thursdays, and Saturdays will be your faster days. The other four days are for recovery.

If you are a runner or cyclist, run a little faster on your hard days and much more slowly on your recovery days. If your muscles feel sore or tight on scheduled hard days, skip that hard workout and do a very easy workout or take the day off. Injuries come from taking a hard workout when your muscles are still sore or tight from a previous intense workout.

HARD DAYS: Start out very slowly and as your muscles feel more comfortable, gradually pick up the pace. When you start to feel the least burning, immediately slow down and remain in that slow pace until the burning is completely gone. Then gradually increase the intensity until you reach the burn again, and immediately slow down. Continue to alternate bursts of increased intensity with slow recoveries until your legs start to feel stiff or you stop recovering from the burn or tightness. Then quit for the day.

EASY DAYS: You are not supposed to feel discomfort or burning on recovery (easy) days. If a workout on a recovery day prevents you from taking your hard workout on the next day, you exercised too intensely or long on your recovery day. Go for as long as you feel good and quit for the day when you feel tightness or discomfort. If you feel stiff or hurt in one group of muscles on one side of your body, take the day off. Soreness in one part of your body is a sign that you are developing an injury.

PROGRAM PROGRESS: Try to increase the intensity of your hard days, and do not increase the intensity of your recovery days. If you avoid injuries, you will become stronger and healthier.

ADVANCED PROGRAMS FOR ATHLETES: Training programs should be based on two very fast interval days, one very fast, prolonged day, and four recovery days. For example, try short intervals on Tuesdays, long intervals on Thursdays and sustained hard workouts or races on Sundays. The other four days are supposed to be so easy that they do not interfere with your recoveries to limit your hard-intense days or worse, cause injuries. Remember, if you do not recover for your next intense workouts, your easy days are too long or too intense, and you should do less, more slowly on your recovery days.

Muscle Cramps in Athletes and Exercisers

This month a study from the University of Cape Town, South Africa showed that the athlete who is most likely to suffer muscle cramps is the one who runs the fastest and the one who has had previous muscle cramps (British Journal of Sports Medicine, June 2011). Of 210 triathletes competing in an Ironman triathlon, 43 developed severe muscle cramps, while 166 did not. There were no significant differences between groups in any pre-race or post- race blood mineral levels or body weight changes (a measure of dehydration). This supports many other studies that show that the most likely cause of muscle cramps in conditioned athletes is muscle damage. The most likely causes of muscle cramps in out-of-shape exercisers are lack of salt or water (1).

Cramps in athletes occur most commonly during intense exercise. Cramps occur far less often during less-intense training, because the most common cause of muscle cramps in exercisers is muscle damage from all-out pressure on the muscles.

Muscle damage: Most muscle cramps in serious exercisers and athletes are caused by an exaggerated "stretch reflex" triggered by muscle damage. When you stretch a muscle, it pulls on its tendon. Stretch reflex nerves in that tendon send a message back to the spinal cord (not the brain), and then the "stretch reflex" in the spinal cord sends a message along nerves from the spine to cause the muscle to contract. During extreme pressure on the muscles, muscles are damaged causing sustained contractions. A study from South Africa showed that the most likely causes of cramps are muscle fatigue or tearing of the muscle itself (2). Electromyograph (EMG) studies measure increased electrical activity from damaged muscles. EMGs show markedly elevated electrical activity of the nerves controlling cramped muscles. Furthermore, a review of the scientific literature shows the most common cause of muscle cramps appears to be muscle damage (3).

Warning signs: Before athletic cramps come on full force, you will usually feel the muscle pulling and tightening. If you slow down, the pulling lessens, but if you continue to push the pace, the muscle goes into a sustained cramp and you have to stop exercising to work the cramp out. Further evidence that muscle damage is the cause of the cramp is that the muscle often hurts for hours or days afterwards.

When a cramp strikes: Muscle cramps during endurance events can be prevented by slowing down when you feel excessive soreness in one muscle group or straining in a muscle. You do this by switching pressure from the cramped leg to the uncramped one. A bicycle racer moves most of his pressure to the pedal of the uncramped leg. A runner shortens the stride of the cramped leg. Continuing to put pressure on the cramped muscle can rupture the muscle.

Prevention: You may be able to prevent cramps by exercising more frequently but less intensely and for shorter periods of time, but most racers do not want to do this.

Other causes in non-athletes: Known medical causes of muscle cramps are extremely rare. If you suffer from recurrent muscle cramps, you may need special tests for pinched nerves, Parkinson's disease, low thyroid, diabetes, narrowed arteries from arteriosclerosis, low blood mineral levels, metabolic diseases that cause muscle damage, or side effects of drugs used for high cholesterol, high blood pressure or diabetes, diuretics, oral contraceptives or alcohol (4).

Dehydration or lack of minerals is less common. Some cramps are caused by low mineral or fluid levels (5). However, for the vast majority of trained athletes who suffer exercise- associated muscle cramps, blood levels of sodium, potassium, calcium and magnesium are normal. Research in athletes after they ran in 52-mile races showed that the runners who suffered cramps had the same level of dehydration and blood minerals as those who did not get muscle cramps.

Athletes should take extra salt anyway. Athletes need more salt than people who do not exercise. They lose a lot of salt through sweat. The most common mineral cause of muscle cramps in untrained people who exercise is lack of salt, according to a report from the University of Oklahoma (6). The authors found that intravenous saline can reverse cramping in exercisers, and that more salt in the diet or in sports drinks can help to prevent heat- associated cramping.

If you are concerned about excess salt raising your blood pressure, get a wrist cuff monitor and check your blood pressure every night before you go to bed. If your blood pressure rises above 120, you may need to restrict salt. (Excess salt can raise systolic blood pressure. Excess body fat, not salt, raises diastolic pressure.

Treatments that usually do not work: Nobody has shown consistent benefit for trained athletes from any of the most common treatments: multivitamin pills; mineral pills with calcium, zinc, magnesium, salt and/or potassium; massage or chiropractic manipulation; drinking large amounts of water; dietary manipulations; or bio-mechanical stretching and strengthening.

Medications: Quinine has been reported to help relieve muscle cramps in non athletes, but it can burst red blood cells. Some studies show that gabapentin (an anticonvulsant), diltiazem ( a blood pressure medication), or B-complex vitamins may help to relieve muscle cramps in some people (7).

Sugar: There is some evidence that taking sugared drinks or foods during prolonged exercise helps to maintain endurance and muscle integrity which helps to prevent cramps. Take a source of sugar frequently during vigorous workouts or races, and back off if you feel a group of muscles pulling or tightening during exercise.

Lack of vitamin D: A leading cause of muscle damage, soreness and slow-healing injuries in athletes is lack of vitamin D. If you suffer frequent cramping and your muscles feel sore or you keep on being injured when you exercise, get a blood test called D3. If it is below 75 nmol/L, your problems may be caused by lack of vitamin D and be cured by getting some sunshine or taking at least 2000 IU each day of the very inexpensive vitamin D3.

Occasional cramps are not harmful. Most racers and serious exercisers accept that occasional cramps will occur, and rarely cause serious injuries.

1. Sports Medicine, April-May 2007
2. Medicine & Science in Sports & Exercise, July 2005
3. Journal of the American Academy of Orthopaedic Surgeons, July 2007
4. Neurology 2010; 74: 691-96
5. The Japanese Journal of Clinical Pathology, November 2007
6. Sports Medicine, April-May 2007
7. Journal of Clinical Pharmacology, 1998;38:1151

Hot Weather Exercise - What to Eat?

To be able to exercise intensely in hot weather, you have to maintain water, sugar and salt in your body for the entire time you exercise. How fast you can ride, run, or exercise is limited by the time it takes to bring oxygen into your muscles. If you can increase the oxygen supplied, or decrease the oxygen needed, you can move faster. Since sugar requires less oxygen to power your muscles than fat or protein, anything that allows your muscles to burn more sugar and less fat will help you to move faster.

Taking extra sugar during a competition or intense exercise lasting more than two hours is far more important than what you eat before your event. The limiting factor to how fast and intensely you can exercise in events requiring endurance depends on how quickly you can get sugar into muscles during exercise. You can markedly improve performance in endurance sports by starting to eat and drink soon after you start exercising.

Do not take in sugar until at least five minutes after you start your competition. When you eat sugar and your muscles are not contracting, you get a high rise in blood sugar that causes the pancreas to release large amounts of insulin. This can cause a drop in blood sugar levels that can tire you. On the other hand, exercising muscles draw sugar rapidly from the bloodstream without needing insulin. So taking sugar during exercise usually does not cause the high rise in blood sugar levels that causes your pancreas to release large amounts of insulin.

The energy for your brain comes almost exclusively from the sugar in your bloodstream. When blood sugar levels drop, so do brain levels, and you feel tired and have difficulty coordinating your muscles.

Another reason why you have to take sugar during intense exercise is that there is only enough sugar in your bloodstream to last three minutes at rest. To maintain blood sugar levels, your liver constantly releases sugar into your bloodstream, but your liver holds only enough sugar to last about twelve hours at rest and far less than that when you exercise. When muscles run out of their stored sugar supply, it hurts to exercise and the muscles become difficult to control.

Don't wait to feel hungry: Hunger during exercise is a very late sign of not getting enough calories. By the time you feel hungry, your body will be so depleted of sugar that you will have to eat large amounts of carbohydrate-rich food just to restore your sugar supplies.

What to eat and drink: All carbohydrates are single sugars, or sugars bound together in twos, up to thousands and millions. Before any carbohydrate can be absorbed into your bloodstream, it must first be broken down into single sugars. Human intestines do not permit combination sugars to pass into the bloodstream, so the most effective way to increase endurance is to take sugar- containing foods and drinks during prolonged exercise.

Caffeine increases sugar absorption from the gut. Taking caffeine when you eat carbohydrate-containing foods and drinks can double your rise in blood sugar (Journal of Caffeine Research, April 16, 2011). A high rise in blood sugar causes all the side effects of diabetes: blindness, deafness, heart attacks, strokes and so forth. However, during exercise, caffeine can increase endurance (Medicine & Science in Sports & Exercise, July, 2010) by increasing the absorption of sugar from your intestines and by increasing the uptake of sugar by your exercising muscles by as much as 26 percent (Journal of Applied Physiology, June 2006). Caffeine is found in coffee, tea, chocolate, cocoa and caffeinated soft drinks.

CAUTION! Take caffeinated sugared drinks only during prolonged, intense exercise. Taking sugared drinks, with or without caffeine, when you are not exercising causes higher rises in blood sugars that increase risk for diabetes and cell damage. Read my comprehensive report on what to eat and drink before and during hot-weather competition

HPV + Sunlight Cause Many Skin Cancers

We have known for many years that the Human Papilloma Virus (HPV) causes almost all warts on the skin, most head and neck cancers, and almost all cervical cancers. Now we find that HPV also causes the common skin pre-cancers called actinic keratoses, which can develop into squamous cell skin cancers that can spread through other parts of the body (Trends in Microbiology, January 2011). More than 60 million Americans suffer from actinic keratoses, scaly areas on sun-exposed skin primarily on the face, ears, scalp, neck, and dorsal surface of the hands.

Most actinic keratosis cells are infected with HPV, the viruses that cause warts (1 - see list of references below). Dr. Eggert Stockfleth, of the Charité Hospital in Berlin, found specific types of HPV (21, 5, 8, 16 and 18) that convert normal skin to the pre-cancerous actinic keratoses, which may then progress to become squamous cell cancers (2).

Recent research shows that these skin pre-cancers are caused by a combination of cumulative exposure to sunlight and HPV, which can be acquired through sexual contact (3).

How skin cancer starts:
Chronic exposure to ultraviolet light damages DNA in skin cells. Your immunity tries to repair this damage, but the Human Papilloma wart viruses can prevent your immunity from repairing the DNA. Most of the time when your DNA is damaged, the cells die because they have a programmable cell death called apoptosis. However, the HPV virus prevents DNA from healing and also prevents the programmable cell death that would have removed the damaged cells (4). Then you develop scaly areas and bumps on your skin called actinic keratoses. With further exposure to sunlight, HPV can cause these damaged cells that do not die to develop into squamous cell skin cancers that can spread through your body.

The more different HPV viruses you have, the more likely you are to develop skin cancers:
More than 150 different types of HPV exist. Some types of HPV (Types 8, 24 and 76) are far more likely to cause skin cancer than others. The ones most likely to cause cervical cancers are types 16, 18, 52 and 59. They are also the ones that persist the longest, and are most likely to cause cancers and abnormal PAP smears.

A person acquires these viruses usually, but not always, from a sexual contact, and then a person's immunity usually clears the virus in six to eight months. However, the more viruses a person picks up from other people, the more likely he or she is to go on to suffer squamous cell skin cancers (5).

The more sexual partners you have, the more likely you are to acquire and keep the cancer-causing HPV virus (6). Men 18 to 70 years old who were free of both HIV and cancer had HPV cultures taken every six months from several places on the penis and scrotum. Among the 1159 men, the incidence of new genital HPV infection was 3.8 percent every six months. Those who had the most sexual partners had the most HPV infections that cause cancer.

Positive cultures for HPV persisted for an average of 7.5 months, and for HPV 16, the type more likely to cause cancer, for 12.2 months. The more partners a person has, the less likely he is to clear the virus. Older people clear HPV faster than younger ones, probably because they have fewer new partners.

Most hpv infections go away:
If you don't acquire any of the other 150 HPV types from additional contact, most HPV infections appear to clear themselves without treatment (7). DNA tests of HPV show that 70 percent of women clear HPV infections in their cervix and vaginas within one year, and only nine percent continue to be infected after two years (8). A summary of several studies shows that 90 percent of HPV tests become negative in about two years.

The current theory is that you become infected with HPV, usually through sexual contact, and it can disappear without treatment, as cultures fail to find it. We do not know if the virus really goes away, but we usually cannot find it. However, some people never clear the high-cancer-risk types of HPV and it is the persistent infections that can lead to skin pre-cancers and cancers (9).

Additional exposure to HPV:
Infected people who continue to have the most sexual contacts are the ones most likely to continue to be infected with HPV. Each additional sexual exposure increases your chances for acquiring additional HPV viruses and the specific viruses that cause cancer.

You can have several different HPV virus types at the same time. Acquiring immunity to one type of HPV does not protect you from becoming infected with another type of HPV in the future. It is likely that the more HPV viruses that infect you and the more sunlight that damages your skin, the more likely you are to develop skin cancer.

How do you get HPV?
The most common way to acquire HPV is through rubbing skin on skin, usually through sexual contact, but any type of rubbing skin on skin has been associated with an increased risk. Non-penetrating skin-on-skin contact has caused HPV transmission even in virgins (10). The virus has repeatedly been found underneath the fingernails, so shaking hands can, at least theoretically, transmit the virus (11). Furthermore, HPV can be transmitted non-sexually from a mother to her child (12). HPV was found in up to 50 percent of pubic and anal hairs removed from patients with genital warts (13).

Condoms do not offer complete protection against HPV since any skin-to-skin contact can result in transmission of the virus (14). The virus can also pass around condoms in body fluids, such as saliva, semen and vaginal secretions.

New sexual partners:
You are most likely to acquire HPV from a new sexual partner, rather than an old one, as healthy people usually clear the virus from their bodies in six to eight months. Each new partner can give you new HPV infections and the more HPV viruses you have at one time, the more likely HPV is to persist and the greater your risk for developing cancers.

Public places:
It is extremely unlikely that you will pick up HPV from a public shower, sauna, or wet seat. Samples were collected with a toothbrush from the floor and seat surfaces of bathing resorts, showers, swimming pools, saunas, bathrooms and dressing rooms. No HPV DNA-positive samples were found (15).

Risk factors for oral cancers:
You are five times more likely to suffer oral cancer from HPV if you have had more than five oral-sex partners in their lifetime. You increase risk for HPV with
• increasing numbers of sexual partners,
• engaging in casual sex,
• having an early age at first intercourse, and
• using condoms infrequently (16).

Cofactors increase risk for cancer from HPV:
Many things you do increase your risk for cancer and the more risk factors you have, the greater your risk. Avoiding these risk factors after you are diagnosed with a cancer can increase your chance for a cure.

Smoking and being infected with HPV both cause fatal squamous cell cancers of the head and neck. A study from the University of Michigan shows that smokers who have an HPV-linked cancer are six times more likely to have a recurrence than those who have never smoked, and two-thirds of patients with HPV-linked tumors were current or former tobacco users (17). Among those with HPV-linked tumors, six percent of those who never smoked had recurrences, compared to 19 percent of those who had smoked in the past and 35 percent of current smokers. Almost all cases of cervical cancers are caused by HPV, but only one woman of 250 infected with HPV develops cervical cancer. If you are infected with HPV and smoke, you increase your chances of developing cervical cancer 15 times (18).

Lifestyle factors that are associated with increased cancer risk (as well as heart attack risk) include: smoking, taking more than two alcoholic drinks per day, being overweight, not exercising, not eating enough fruits and vegetables, eating too much saturated fat from mammals, eating burnt food (PAHs and HCAs), lack of vitamin D, lack of sunlight, and anything that increases risk for diabetes. Other risk factors include promiscuous behavior that exposes you to hepatitis B and C viruses, HPV, human immunodeficiency virus (HIV), Helicobacter pylori (H. pylori), Human T-cell leukemia/lymphoma virus (HTLV-1), Epstein-Barr virus (EBV), or Human herpes virus 8 (HHV8); working in jobs that expose you to radiation, chemicals such as asbestos, benzene, benzidine, cadmium, nickel, or vinyl chloride, certain metals, pesticides or solvents; taking certain medications and hormones; repeated exposure of your skin to excess sunlight or getting too many X rays.

Treatment of genital warts:
Virtually all genital warts are caused by HPV. Doctors treat genital warts by burning, freezing, lasering, scraping, or removing them surgically. They use chemicals to sensitize skin to sunlight and then use light to burn the warts off. They even peel them off. However, warts often return after all destructive procedures, so I usually recommend
• Fluoro-uracil cream (an anti-cancer drug),
• Imiquimod cream (a chemical that increases your immunity), or
• Diclofenac sodium gel (a drug that blunts your immune reaction).

Treatment for actinic keratoses:
I think that the most effective treatment for actinic keratoses is to use a generic version of imiquimod cream (brand name Aldara). It enhances your immunity so it can more effectively kill HPV. It is applied twice a week for 16 weeks, left on the skin for about eight hours and then washed off.

Current treatment by most dermatologists is to destroy the lesions of actinic keratoses with liquid nitrogen or electrocautery. Surgery is rarely needed. However, once an actinic keratosis becomes a squamous cell carcinoma, surgeons usually remove the entire cancer. A pathologist usually checks the removed tissue to see that there is a 360-degree margin of non-cancerous skin around the removed cancer.

1. New England Journal of Medicine, May 15, 2003
2. Disease Markers, April 2007
3. Expert Review of Dermatology, April 2010
4. Cancer Detection and Prevention, June 2001
5. BMJ. 2010;341:c2986
6. The Lancet, published online March 1, 2011
7. Am J of Ob and Gyn, 2000;183(3): 561-567
8. NEJM, 1998;338(7):423-428
9. Trends in Microbiology, 2011(Jan);19(1):33-39
10. Scand J Infect Dis 1996;28(3):243-6
11. Sexually Transmitted Infections 1999 Oct;75(5):317-9
12. J Med Virol 1998 Nov;56(3):210-6
13. J Clin Microbiol. 1999 Jul;37(7):2270-3
14. Am J Epidemiol 2003 Feb 1;157(3):218-26
15. Rev Med Virol 1999 Jan-Mar;9(1):15-21
16. NEJM May 9, 2007
17. Clinical Cancer Research, February, 2010
18. Cancer Epidemiology, Biomarkers & Prevention, November 2006

Diverticulosis? Seeds and Nuts OK

People with diverticulosis are usually told to avoid seeds and nuts, yet no scientific data support this recommendation (Nutrition in Clinical Practice, March 2011). Diverticulosis means that the colon has multiple outpouchings. The theory is that small food particles such as seeds might get caught in the outpouchings, but no one has shown that this actually happens. Furthermore, avoiding insoluble fiber found in all parts of plants is likely to increase risk for diverticulosis.

When solid food reaches the stomach, the pyloric sphincter closes and food is allowed to pass into the intestines only after it is converted to a liquid soup. It remains a liquid soup until it reaches the colon where fluid is rapidly absorbed to form solid material. Fiber is found in all foods from plants. It is composed of sugar molecules bound together so tightly that humans lack the enzymes necessary to separate out individual sugar molecules. Only single sugar molecules can be absorbed into the bloodstream. Thus fiber cannot be absorbed so it passes to the colon in the liquid soup.

The fiber holds water in the colon and helps keep the stool from becoming so hard that it blocks the passage of gas formed in the colon. Pressure increases behind the hard stool, swelling the colon to cause outpouchings called diverticula. Seeds, nuts and other plant materials help to keep stool soft and prevent diverticula from forming. On the other hand, refined flour that has had the fiber removed cannot hold much water, so it causes hard stool that is more likely to obstruct the passage of gas and increase the chance that outpouchings will form in the colon.

"White Whole Wheat" Breads

"White whole wheat" breads are made with flour ground from a variety of wheat that has a white outer covering, not brownish-red. That's why the flour is pale in color rather than light brown. So nutritionally it is equivalent to bread made from ordinary (brown/red) whole wheat. HOWEVER, when you grind ANY grain into flour, you lose a major benefit of whole grains -- see WHOLE Grains are Better than Any Flour.

Antioxidant Pills Reduce Exercise Benefits

The current issue of Journal of the American College of Sports Medicine shows that antioxidant pills prevent the major mitochondrial benefits of athletic endurance training (Medicine & Science in Sports & Exercise, June 1, 2011). Rats that trained on a treadmill increased the enzymes that are necessary to increase the number and size of mitochondria. Rats who trained on a treadmill and were given two powerful antioxidants, vitamin E and alpha lipoic acid, did not increase the enzymes that are necessary to increase the number and size of mitochondria.

How humans get their energy for exercise: Humans convert food to energy most effectively in the mitochondria, hundreds of small chambers inside muscle fibers. They need oxygen to do this. The limiting factor to how fast and long you can move is the time it takes to move oxygen into muscle fibers. Athletic training makes you faster and gives you greater endurance by enlarging and increasing the number of mitochondria in muscles.

Antioxidant pills can harm: People who take 1000 mg/day of vitamin C and 400 IU/day of vitamin E do not gain the benefits of increased insulin sensitivity when they exercise (Proceedings of the National Academy of Sciences, May 12, 2009).

• When blood sugar levels rise too high, sugar sticks on the surface of cell membranes and can never get off. The attached sugar is converted in a series of chemical reactions to sorbitol that destroys cells.

• Contracting muscles help to prevent this damage by removing sugar so fast from the bloodstream that blood sugar levels do not rise too high.

• Food is converted to energy to power your muscles by a series of chemical reactions that shuffle electrons from molecule to molecule.

• This occurs primarily in the mitochondria, small energy-producing chambers in cells, that number anywhere from a few to thousands in each cell.

• As electrons are shuffled to produce energy, extra electrons can accumulate. They can either end up on hydrogen atoms to form water and become harmless, or they can end up on oxygen atoms to form free radicals that can damage cells. This can cause cancers, heart attacks and other life-shortening conditions.

• Exercise speeds up the reactions that turn food into energy, so exercise increases the production of free radicals.

• The body responds to this increased production of free radicals during exercise by producing tremendous numbers of antioxidants that sop up the free radicals and render them harmless.

• Exercise prolongs life and prevents heart attacks and cancers by causing the body to dispose of free radicals by the increased production of antioxidants.

Let the buyer beware: If you exercise and take antioxidant vitamins C and E, you prevent your own body from making large amounts of antioxidants during exercise, so more free radicals (oxidants) accumulate in your body and more cells are damaged.

Many studies show that:

• Taking large doses of beta carotene (pro-vitamin A) increases risk for heart attacks in men and increase risk for lung cancer in smokers.

• Taking large doses of vitamin C does not prevent colon cancer, and does not prolong life in people with cancer.

• Taking large doses of vitamin E or selenium does not prevent lung cancer, heart disease or stroke.

My recommendations: Exercise every day, and get the antioxidant vitamins and other nutrients your body needs from foods, not from pills. Eat a wide variety of foods including large amounts of fruits, vegetables, whole grains, beans, nuts and other seeds. If you want to take Recommended Dietary Allowances of vitamins in pills, go ahead; there is little evidence that you will harm yourself. However, when you take large doses of any vitamin, you don't have the foggiest idea whether you are harming or helping yourself. I do not recommend large doses of vitamins to anyone.

Heat Stroke and Hyponatremia

The most likely cause of death during hot weather sports is heat stroke, when the body temperature rises so high that it cooks the brain (Medicine and Science in Sports and Exercise, July 2008). Nobody should ever die of heat stroke because your body sends you warning signals as your temperature rises. Those most likely to suffer heat stroke are those who have arteriosclerosis, are overweight or are in poor shape. The treatment for a person who collapses from heat stroke is immediate immersion in cold water.

In 1965, I almost died from heat stroke in an unimportant local race in Arlington, Virginia. I am still embarrassed by the stupidity that I showed when I ignored all of the warning signs as my temperature continued to climb.

Signs of impending heat stroke
First your muscles are affected, then your circulation and then your brain. As your temperature starts to rise, your muscles feel like a hot poker is pressing against them.

It is normal for intense exercise to make your muscles burn, but hard exercise does not cause painful burning that feels like fire. Furthermore, the burning of hard exercise is relieved by slowing down. The muscle burning of impending heat stroke does not go away when you slow down.

As your temperature rises further, the air that you breathe feels like it's coming from a furnace and no matter how rapidly and deeply you try to breathe, you can't take in enough air. When you exercise intensely, you can become very short of breath, but the air you breathe will not burn your lungs. Burning in your lungs, not relieved by slowing down, signals impending heat stroke.

When you feel that the air is so hot that it burns your lungs, stop exercising. This sign means that your heart cannot pump enough blood from your exercising muscles to your skin, so heat is accumulating rapidly and your temperature is rising rapidly. Your temperature is now over 104 and continuing to exercise will raise your body temperature even further and it will start to cook your brain.

Your head will start to hurt, you'll hear a ringing in your ears, you may feel dizzy, you may have difficulty seeing and then you will end up unconscious. Your temperature is now over 106 and your brain is being cooked just as the colorless portion of an egg turns white when it hits the griddle.

When does heat stroke occur?
Almost all cases of heat stroke occur when you suddenly increase the intensity of your exercise, such as the finishing sprint of a long distance running or cycling race, or an intense run down the field in soccer.

How body temperature can rise uncontrollably
An excessive rise in body temperature is caused either by producing too much heat or by inability to dissipate the extra heat. When you exercise, almost 80 percent of the energy that is used to drive your muscles is lost as heat. That means that the harder you exercise, the more heat you produce.

During exercise, more than 70 percent of the energy used to drive your muscles is lost as heat. Your heart has to pump extra blood from your hot muscles to your skin where you sweat. Sweat evaporates and cools your skin to dissipate the heat. The harder you exercise, the more heat your muscles produce. Everyone who exercises, particularly in hot weather, has to sweat to keep the body temperature from rising too high.

Drugs can cause heat stroke
Heat stroke is more likely to be caused by inability to get rid of heat than by producing too much heat. Stimulants such as amphetamines or cocaine can kill athletes by preventing them from getting rid of heat by blocking sweating and blood flow to the skin. A single nasal dose of cocaine can block blood flow to the skin and sweating, to prevent a person from cooling his own body (Annals of Internal Medicine, June 4, 2002).

When a person passes out from heatstroke, get medical help immediately. Any delay in cooling can kill him. Carry the victim rapidly into the shade and place him on his back with his head down and feet up so blood can circulate to his brain. Cool him by pouring on him any liquids you can find or spray him with a hose. It doesn't make any difference what you pour on him: milk, Coca Cola, beer, or anything else. Evaporation of any liquid cools. As you cool him, he will then wake up and talk to you and act like nothing has happened. While he's sitting or lying there, his temperature can rise again and he can go into convulsions or pass out again, so he must be watched for at least an hour.

An athlete or exerciser who passes out from overheating should be immersed in cold water immediately to prevent brain and multiple organ damage. However, a heart attack can also cause a person to pass out and this should not be treated with cold water immersion. Therefore always get medical help immediately when you see a person pass out during exercise.

Heat stroke is caused by continuing to exercise intensely in spite of all the warning signals that the body presents. Dehydration also increases your risk for heat stroke.

When you compete in sports, you need to drink before you feel thirsty, because you slow down and lose power long before you have any signals to tell you that you are dehydrated. In warm weather, trail runners raced 12 km (7.2 miles) much faster when they took fluids (Journal of Athletic Training, March-April 2010). With fluids, they averaged 53.1 minutes compared to 55.7 minutes without fluids. Immediately after the race, the dehydrated runners had signs of greater body stress such as heart rates six beats per minute faster and intestinal temperatures .22 degrees C higher.

Thirst is a late sign of dehydration
You won't feel thirsty during exercise until you have lost between two and four pints, or two to four pounds. Thirst is a very late sign of dehydration. You sweat during exercise, and since sweat contains much less salt than your blood, you lose far more water than salt during exercise. As blood salt levels rise higher and higher, they trip off special osmoreceptors in your brain to tell you that you are thirsty. Since it takes a long time for blood salt levels to rise high enough to tell you that you are thirsty, you will be severely dehydrated long before you feel thirst.

You need more sugar in hot weather
During long sports competitions, you need to take sugar as well as fluid because running out of sugar stored in muscles slows you down. The only mineral that you need to replace during exercise is common table salt. Water or your favorite drink plus food containing sugar and salt are just as effective as any sports drink to maintain endurance and prevent heat exhaustion. The best exercise drink is the one that tastes best to you, because that's what you will drink the most (International Journal of Sport Nutrition and Exercise Metabolism, January 2002).

Up to fifteen years ago, athletes were advised to drink as much as they could to insure that they did not lose any weight during endurance competitions. This caused a condition called HYPONATREMIA which has killed some novice cyclists, runners and athletes in other endurance sports. It occurs almost never in trained athletes because it is most likely to occur in people who slow down so much that they spend too much time drinking fluids and too little effort maintaining pace. During competitions, you work so hard to maintain pace that you have to conscientiously work just to drink enough.

How hyponatremia kills
Hyponatremia is caused by drinking too much fluid, not by excessive loss of salt in sweat or by the stress of exercising. The extra fluid expands blood volume and dilutes blood salt levels. This causes blood salt levels to drop too low, while brain salt levels remain normal. Fluid moves from an area of low salt concentration into areas with high salt levels, so fluid moves from the bloodstream into the brain, causing brain swelling. Since the brain is enclosed in the skull, which is a tight box, the brain expands and has nowhere to go, so it is squashed to cause headache, nausea, and blurred vision.

Blood tests only way to diagnose hyponatremia
Since the symptoms of hyponatremia are the same as those caused by pure dehydration with normal blood salt levels, the only way to diagnose the condition is with blood tests. As blood salt levels drop even lower, the person becomes confused, develops seizures and falls unconscious. You should suspect hyponatremia when the event takes more than four hours and the athlete has been drinking often during the event. Anyone who is confused, passes out or has seizures should be sent to a hospital immediately. Hyponatremia requires skilled management because the first impulse of an inexperienced physician is to give intravenous fluids, which dilute blood salt levels further, causing more brain swelling that can kill the patient.

How much fluid should you drink?
You will not become thirsty during exercise until you have lost between two and four pints of fluid, so you can't wait for thirst to encourage you to drink. Dehydration makes you tired and it is unlikely that you can replace the lost fluid during a race after you have become thirsty. The American College of Sports Medicine recommends a limit of 1200cc (5 cups, 2.5 pints, a little over 1 quart, or 2 average size water bottles) per hour, but for a person who is not exercising near his or her maximum, this could be too much (Clinical Journal of Sport Medicine, July-August 2005). A person exercising near his capacity and not slowed down by fatigue probably does not have to worry about limiting fluid intake. He is working so hard to maintain intensity that he doesn't have enough time to drink too much. On the other hand, people slowed down by fatigue or those who are out of shape should limit fluid intake, probably to less than two water bottles per hour.

Drink to avoid thirst
No studies show that forced drinking of fluids is any more effective than just drinking frequently to avoid thirst (Annals of Nutrition and Metabolism, November 2010). So current advice is to drink frequently, but just try to avoid feeling thirsty. You are in trouble with dehydration when you start to feel thirsty. Thirst is such a late sign of dehydration that once you feel thirsty, it is too late for you to catch up on your fluid needs during competition.

The Dangers of Fructose

An ever-increasing number of studies show that sugared drinks and foods cause fatty liver, obesity, high blood pressure, diabetes, heart attacks, kidney damage and premature death. A review of recent studies shows that fructose may be more damaging than other sugars (Journal of the American Society of Nephrology, November 29, 2010).

Fructose is found in:
• fruit juices (sucrose, which is glucose and fructose bound together in a single molecule),
• table sugar from sugar cane and beets (sucrose),
• honey (mostly glucose and fructose separate from each other), and
• drinks and foods that contain High Fructose Corn Syrup (glucose and fructose, separate from each other).
• Sucrose is also found in most fruits and many vegetables.

Sucrose contains 50 percent fructose and 50 percent glucose bound together. High Fructose Corn Syrup contains approximately a 55/45 proportion of fructose and glucose. As far as the body is concerned, the ratio of glucose to fructose is not important. The issue is whether fructose is more harmful than glucose.

Glucose, but not fructose, can circulate in your bloodstream
Only single sugars can pass from your intestines into your bloodstream. The double sugars, such as sucrose in fruits or lactose in milk, have to be broken down into single sugars before they can be absorbed. Glucose is the only sugar that is allowed to circulate through your body. Fructose cannot circulate in your bloodstream. Fructose is absorbed from your intestines into the blood vessels that carry blood to your liver, where it is immediately converted to glycogen, the stored sugar in your liver, or to triglycerides, a type of fat.

When the liver's stores of glycogen are needed for energy, the glycogen is converted into glucose and released into the bloodstream. After glucose is absorbed into the bloodstream, it passes into your general circulation and is used for energy for your brain, muscles and other tissues. Glucose in your blood supplies almost 98 percent of the calories necessary for your brain to function, which is why a sudden drop in blood sugar can cause you to pass out.

How fructose causes liver damage, obesity, diabetes and death
Your liver converts excess fructose into triglycerides.
• are building blocks for the bad LDL cholesterol that forms plaques in arteries,
• can be stored in your liver to cause a fatty liver,
• can be stored in your fat cells to make you obese.

Having excess triglycerides in your liver:
• causes a condition called fatty liver which interferes with normal liver function; and
• causes fat to be stored in your belly and decreases insulin sensitivity to cause diabetes (Journal of Clinical Investigation, May 2009).

Triglycerides can pass into your bloodstream to:
• damage your kidneys to cause high blood pressure, and
• in very high amounts, can form clots in your bloodstream.

All of these side effects of excess triglycerides increase your risk for heart attacks and strokes.

Who is harmed by fructose?
Fructose appears to be safe if:
• You don't eat large amounts. You have to take in a lot of fructose to raise your triglycerides and become insulin insensitive. Small amounts will not harm you.

• You are not overweight. The fatter you are, the more likely you are to become diabetic. Full fat cells send out hormones of inflammation that block insulin receptors to increase risk for diabetes.

• You do not store fat primarily in your belly. Storing fat primarily in your belly means that you are already insulin insensitive and have high blood insulin and sugar levels. High levels of insulin cause fat to be stored specifically in the liver and belly.

• You exercise regularly. Contracting muscles draw sugar so rapidly from the bloodstream that there is less fructose available to be turned into triglycerides.

• You get your fructose from fruit, not fruit juice. Fructose in fruit is absorbed far more slowly than fructose in fruit juice. The fiber in fruit can keep fruit in your stomach for up to five hours and markedly slows absorption to reduce blood sugar levels. On the other hand, the sugar in fruit juice passes directly into the intestines to be absorbed immediately and cause a high rise in blood sugar. A high rise in blood sugar causes sugar to stick to cell membranes that causes irreversible damage.

Fructose helps athletes and exercisers
Fructose can be an athlete's best friend. When you exercise, your muscles and brain constantly draw sugar from your bloodstream as a source of energy. The energy for your brain is supplied by sugar in your bloodstream. There is only enough sugar in your bloodstream to last 3 minutes. So your liver has to constantly release sugar from its cells into your bloodstream. However, there is only enough sugar in your liver to last 12 hours at rest, and far less than that during exercise. Your liver can run out of its stored sugar and your blood sugar level can drop, you feel dizzy, lose all muscle strength and can pass out and suffer seizures. Cyclists call this "bonking." Bonking is common in bicycle racers who do not eat frequently during long races, but it is rare in long distance runners. When you run, your leg muscles are damaged from the constant pounding on the roads and you must slow down. However, you pedal in a smooth rotary motion which does not damage your muscles, so you can continue to pedal at a rapid cadence for many hours, until you run out of sugar.

Fructose is the best and most efficient sugar to keep up liver glycogen during competition and to replenish liver stored after an intense workout (Medicine & Science in Sports & Exercise, March 2011). Bicycle racers who ingest drinks that contain fructose can replace lost liver glycogen four times as fast as those who take drinks containing only glucose.

Glucose plus fructose is better than just fructose
If you exercise for more than a couple hours, you can use up almost all of your (stored liver glycogen. Taking drinks that contain both fructose and glucose will keep you going far more efficiently than if you take only one of these sugars (International Journal of Sport Nutrition and Exercise Metabolism, April 2010; Scandinavian Journal of Medicine & Science in Sports, February 2010). Most bottled sports drinks and sugared soft drinks in North America are sweetened with high-fructose corn syrup, containing glucose and fructose in close to equal portions.

No fructose when you are not exercising
Loading with sugared drinks and foods is safe only for people exercising intensely for more than two hours at a time. Low intensity exercise or exercising for less than two hours will not protect you from the potential damage caused by sugared drinks.

How exercise prevents fatty liver and prolongs life
Any exercise that you do will help to protect you from the ravages of sugared foods and drinks. It is usually safe to take sugared drinks while you exercise because blood sugar levels rarely rise too high during exercise or for up to an hour afterward. Contracting muscles draw sugar so rapidly from the bloodstream that there is no sharp rise in blood sugar.

• Contracting muscles help to prevent the high rise in blood sugar that follows eating refined carbohydrates during rest (American Journal of Clinical Nutrition, July 2008).
• Unlike resting muscles, contracting muscles do not require insulin to move sugar inside their cells (Journal of Applied Physiology, July 2005).
• Contracting muscles remove sugar maximally from the bloodstream, without needing insulin, during & up to one hour after exercise. The effect tapers off to zero at about 17 hours (Journal of Applied Physiology, February 2010).

You should avoid sugared drinks at rest
I recommend that you avoid all sugared drinks (sugared sodas and fruit juices) and foods with added sugars except during vigorous exercise.

What to drink during sports that require intense exercise for more than an hour:
Drink any sugared drinks. Ordinary beverages containing both glucose and fructose are probably best; there is no need to seek out special sugars or sugar combinations.

Caffeine: Good When You Exercise, Bad When You Rest

Caffeine increases sugar absorption from the gut. Taking caffeine when you eat carbohydrate-containing foods can double your rise in blood sugar (Journal of Caffeine Research, April 16, 2011). Since more than 35 percent of North Americans will become diabetic and have high rises in blood sugar levels after meals, most people should not take caffeinated drinks with meals that contain carbohydrates: bread, spaghetti, or sugared foods and drinks. If you are already diabetic, your blood sugar levels rise even higher and you suffer cell damage. A high rise in blood sugar causes all the horrible side effects of diabetes: blindness, deafness, heart attacks, strokes and so forth. However, during exercise, caffeine can increase endurance (Medicine & Science in Sports & Exercise, July, 2010) by increasing the absorption of sugar from your intestines and by increasing the uptake of sugar by your exercising muscles by as much as 26 percent (Journal of Applied Physiology, June 2006). Caffeine is found in coffee, tea, chocolate, and cocoa.

Sugared drinks cause higher rises in blood sugar than sugared foods.
No solid food is allowed to pass into your intestines. After food enters your stomach, the pyloric sphincter closes. Food is kept in the stomach until it is turned into a liquid soup. Then the stomach muscles squeeze the soup through the pyloric sphincter into the intestines. An orange can be kept in your stomach for up to five hours before it passes into your intestines. Since fruit juice is a liquid, it passes into your intestines immediately. So orange juice causes an immediate high rise in blood sugar, while an orange does not. Studies show that fruits decrease diabetes risk, while fruit juices increase risk (Diabetes Care, July 2008).

Caffeine drives blood sugar levels even higher.
Adding caffeine to sugar in a drink causes blood sugar levels to rise even higher than drinks that have only sugar.

Fruit juice is as damaging as high fructose corn syrup or table sugar.
High Fructose Corn Syrup (HFCS) has been blamed for the ever-increasing rates of obesity and diabetes in North America over the last forty years. However, HFCS appears to be no more damaging than fruit juice or drinks sweetened with table sugar. Most soft drinks are sweetened with HFCS. Both HFCS and conventional sugar (sucrose) contain a mixture of two sugars, glucose and fructose, in nearly the same concentrations: HFCS has 55 percent fructose/42 percent glucose, while sucrose is a 50/50 mixture. These numbers are so close that most researchers feel that the slight increase in the concentration of fructose is not important enough to cause disease in itself. The fructose in orange juice, table sugar and HFCS are equally damaging to your health.

How fructose harms:
Fructose is far more damaging to the liver than glucose and is thought by many physicians to be the main cause of the fatty liver that causes insulin insensitivity and type II diabetes. When your blood sugar rises too high, the pancreas releases large amounts of insulin. Insulin converts sugar to triglycerides. Since high levels of blood triglycerides increase risk for clots, your good HDL cholesterol carries the triglycerides from your blood to your liver to fill up the liver with fat to cause a fatty liver. Fructose causes far higher blood and liver levels of triglycerides than glucose does, so fructose is a more potent cause of a fatty liver. Having a fatty liver prevents the body from responding to insulin and blood sugar levels rise to increase diabetes risk.

During exercise, muscles protect you.
Resting muscles are inactive. They need insulin to remove sugar from your bloodstream. On the other hand, contracting muscles can remove sugar from your bloodstream without even needing insulin (American Journal of Clinical Nutrition, July 2008). The maximum effect is during exercise and continues maximally for up to one hour afterward and disappears at around 17 hours (Journal of Applied Physiology, February 2010).

How caffeine and sugar help you during exercise:
Caffeine increases endurance by helping the body use more sugar from drinks that you take during exercise (Journal of Applied Physiology, June, 2005). The limiting factor to how fast you can move over distance is the time it takes to get oxygen into muscles. Since sugar requires less oxygen than fat or protein do, muscles move faster with more power when they burn sugar. Those who took sugared drinks with caffeine were able to absorb and use 26 percent more of the ingested sugar than those who took the same drinks without caffeine. Caffeine-laced drinks help improve endurance even more in hot weather (International Journal of Sport Nutrition and Exercise Metabolism, February 2011).

You should take caffeinated sugared drinks only when you exercise and for up to an hour after you finish. Taking sugared drinks, with or without caffeine, when you are not exercising causes higher rises in blood sugars that increase risk for diabetes and cell damage.

Sugar and Refined Carbohydrates in Your Diet

Since the 1940s, North Americans have suffered an incredible increase in disease. Today, 70 percent are overweight, 35 percent become diabetic, 40 percent die of heart attacks, and we have very high rates of certain cancers. Major culprits appear to be refined carbohydrates and lack of exercise.

In the late 1940s, Ancel Keys noted the increasing heart attack rate in North America and blamed dietary saturated fats and cholesterol in animal products. John Yudkin in England blamed sugar. At that time, Ancel Keys won the debate and Fred Staire, the chairman of Nutrition at Harvard School of Public Health and a personal friend of mine, wrote that sugar is safe. John Yudkin died discredited in 1997, but today it appears that he was a prophet.

Due to the acceptance of Ancel Keys' views, scientists developed drugs to lower cholesterol and told people to avoid saturated fats. The rate of heart attacks has gone down, primarily because of drugs and a better understanding of what causes them. Yet the incidence of diabetes and obesity keep rising. The culprits appear to be refined carbohydrates, particularly all sugars.

High blood sugar damages every cell in your body. After a person eats refined carbohydrates, particularly any sugared drinks, blood sugar can rise too high. This causes sugar to stick to the outside surface of cell membranes where it is converted by a succession of chemical reactions to sorbitol which destroy the cell to damage every cell in your body to cause blindness, deafness, heart attacks, strokes and all the side effects of diabetes.

Being fat causes high blood sugar levels. Before insulin can do its job of driving sugar into cells, it must first attach on special hooks on cells called insulin receptors. Fat inside cells blocks insulin receptors. Muscle cells full of fat cannot respond to insulin and the sugar remains in the bloodstream. Full fat cells send out hormones that block insulin receptors to prevent insulin from clearing sugar from the bloodstream.

High rises in blood sugar make you fat and cause diabetes.
When blood sugar levels rise too high, the pancreas releases large amounts of insulin. Insulin converts sugar to triglycerides. If you do not burn these triglycerides for energy, they fill fat cells with fat and you gain weight. Full fat cells block insulin receptors so blood sugar rises and you become diabetic.

Exercise helps to prevent diabetes.
Sugar cannot enter resting muscles unless insulin is there to drive the sugar into muscles. However actively contacting muscles can draw sugar from the bloodstream without needing insulin. So during exercise, muscles can remove sugar from the bloodstream to prevent the extra sugar from damaging cells and being converted to fat. It also helps make insulin receptors on cells respond to insulin and push sugar into cells.

You need to exercise every day.
Muscles draw sugar from the bloodstream without insulin only when they are actively contracting or lack oxygen and they can continue drawing sugar without insulin maximally for up to an hour after you finish exercising. They lose all ability to remove sugar without insulin 17 hours after you finish exercising. Since the sugar-lowering benefit of exercise lasts in muscles no more than 17 hours, you must exercise every day to retain this benefit.

The highest rises in blood sugar come from sugar in drinks.
All sugared drinks cause very high rises in blood sugar levels. Orange juice will cause the same high rise in blood sugar as sugared soft drinks. When food enters your stomach, the pyloric sphincter at the end of the stomach closes. Then solid food is converted to a liquid soup that is pumped into the intestines by stomach muscle contractions. An orange can stay in your stomach up to five hours, while orange juice passes immediately into your intestines where it is absorbed, causing a rapid rise in blood sugar.

Foods made from flour also cause high rises in blood sugar.
Grains are seeds of grasses. They have a thick capsule that is so tough that you have to cook them for at least an hour just to make them palatable. Blood sugar barely rises after you eat WHOLE grains. However when you grind whole grains into a powder, the flour that is formed can enter the bloodstream immediately to cause a high rise in blood sugar. So pastas and breads can cause high rises in blood sugar, even if they are made from whole grains.

Diabetics should eat fruits and whole grains, and so should you.

Fruits are full of sugar. However, diabetics who do not eat fruits do very poorly. Everyone should eat fruits and whole grains, even those who are overweight, diabetic, or have high cholesterol levels. Everyone should restrict sugared drinks and flour, particularly if they are overweight, diabetic or have heart problems.

Where does meat fit into this picture?
The saturated fat in red meat has been shown to block insulin receptors and raise blood sugar levels. The monounsaturated fats in fruits, whole grains and vegetables have been shown to unblock insulin receptor.

What's the best way to lower high cholesterol?

The best way to lower cholesterol is to restrict calories. It is far more effective than restricting dietary fat and dietary cholesterol. If you ate nothing but fatty meat and reduced your calories by a third, your cholesterol would drop significantly. The cholesterol that you eat in meat, fish and chicken goes to your liver where it is broken down into 2-carbon units. If you do not have enough calories, these 2-carbon units are burned for energy. On the other hand, if you have lots of extra calories, the 2-carbon units are converted to cholesterol to raise your blood cholesterol level.

What is a healthful diet?
You can eat all the fruits, vegetables, whole grains, beans, seeds and nuts you want. You should restrict all refined carbohydrates made from flour and avoid sugared drinks, except when you are exercising. I believe that you should also avoid red meat; AND you should exercise every day.

Deep Muscle Soreness after Prolonged, Intense Exercise

You should stop exercising for several days when you feel deep muscle soreness after very long exhaustive exercise such as running a marathon (26 miles), cycling a century (100 miles), going on a very long hike or lifting heavy weights repeatedly for a long time. Prolonged deep muscle soreness after running a long distance very fast is characterized by severe damage to the muscle fibers themselves. The muscle fibers are torn, the cell membranes are ruptured and the internal content of cells leak outside into the surrounding tissue (J Neuro Sci 1983;59:185-203). Of course, you do not need to stop exercising for the mild muscle soreness that you feel after a normal hard workout.

The deep muscle soreness that follows hard running is far less likely to occur in cyclists, swimmers or athletes in other sports because running causes eccentric contractions, while swimming and cycling usually do not. Muscles move your body by pulling on bones when they shorten. However if your sport forces muscles to lengthen when they contract, the severe force on the muscles caused by eccentric contractions (stretching during contraction) tears the fibers and ruptures the membranes. When you run fast, particularly down hills, your thigh muscles try to keep the knee and hip from bending excessively when your heel hits the ground, and they are stretched and torn.

The severe soreness from muscle damage is virtually always reversible, will almost always heal completely without treatment, and is part of the training process. Mild casual exercise does not help you to heal faster, so you might just as well curtail your running for a few days until the soreness lessens. You should not resume intense exercise until the soreness disappears completely.

Highly trained, competitive athletes will recover faster by eating a diet rich in protein and carbohydrates. However, less-conditioned people with muscle soreness will only gain weight if they increase food consumption.

Although many athletes believe that massage, stretching, or cross training help to relieve deep muscle soreness, scientific research has failed to prove that they actually hasten the recovery process.

HPV and Cancer

How do you get HPV? You acquire Human Papilloma Virus (HPV) through direct skin to skin contact with an infected person, through vaginal, penile, oral, or anal sexual contact, even if a person has no warts. The more sexual partners you have, the more likely you are to be infected and develop cancers from it. These viruses cause virtually all cases of cervical cancer and many cancers of the skin, vagina, penis, anus, mouth, nose, head and neck. Using condoms helps reduce your chances of becoming infected, but does not offer complete protection. Six million North Americans are newly infected each year, Twenty million are infected now with HPV, and more than 80 percent of sexually-active men and women have been infected.

Types of HPV: More than 150 different HPV viruses have been found, and the ones most likely to cause cancers are types 16, 18, 52 and 59. They are also the ones that persist the longest, and are most likely to cause cancers and abnormal PAP smears.

Can I ever get rid of HPV? Doctors cannot cure HPV, they can only destroy the warts caused by these viruses with chemicals or remove them with surgery. Most infections appear to clear themselves without any treatment (Am J of Ob and Gyn, 2000;183(3): 561-567). DNA tests of HPV show that 70 percent of women clear HPV infections within one year, and only nine percent continue to be infected after two years (NEJM, 1998;338(7):423-428). A summary of several studies shows that 90 percent of HPV tests become negative in about two years. The current theory is that you become infected with HPV through sexual contact and it can disappear without treatment, as cultures fail to find it. We do not know if the virus really goes away, but we often cannot find it. However some people never clear the high-risk HPV types and it is the persistent infections that can lead to cancers (Trends in Microbiology, 2011(Jan);19(1):33-39). Each additional sexual exposure increases your chances of acquiring additional HPV viruses and the specific viruses that cause cancer. You can have several different HPV virus types at the same time. Infected people who continue to have the most sexual contacts are the ones most likely to continue to be infected with HPV, as each new exposure carries risk for a new infection.

How long does it take for the virus to become undetectable? The average time for a person who has acquired HPV to have the virus unavailable for culture is six months. However, those with high risk HPV 16 and 18 took an average of almost eight months for the virus to become non-detectable. Again, we do not know if it really goes away.

Does having the virus cause abnormal pap smears? Most women who are infected with HPV will not develop a positive PAP test.

Immunization: Immunization protects you from infection with the viruses in that vaccine. It does not protect you from the many viruses not in the vaccine. High risk HPV subtypes are associated with almost all cervical cancers. Available HPV vaccines contain high risk HPVs 16 and 18.

How Exercise Keeps You Young (and Prolongs Your Life)

Dr. Mark Tarnopolsky, of McMaster University in Hamilton, Ontario, has shown that exercise prevents aging in mice programmed to grow old rapidly (The Proceedings of the National Academy of Sciences, September 22, 2010). The exercising mice did not have the expected shrinkage with aging of their brains, hearts, muscles, skin, hair, ovaries, testicles, spleen, kidneys, and liver. Many other studies show that exercise in later life slows signs of aging such as loss and graying of hair, weaker and smaller muscles, loss of brain function and size, thinning of skin, damage to blood vessels associated with heart attacks and strokes, loss of apoptosis associated with increased cancer risk, and loss of sexuality associated with shrinking of testicles and ovaries.

The explanation for these incredible findings appears to be in the mitochondria that convert food to energy for your body. At all ages, the exercising mice appeared younger and healthier than the non-exercising mice. Mitochondria have a different DNA than other cells in mammals. That means that in the process of evolution, bacteria invaded cells and provided the ability to turn sugar to energy more efficiently than any other process in the body. Aging in humans is associated with loss of function and number of mitochondria which causes decline in tissue functions that causes cancers, arteriosclerosis, diabetes, and Parkinson's and Alzheimer's disease. With aging, genetic mutations cause mitochondria to malfunction and die and you to look older.

As you age, you lose your ability to make AMP-activated protein kinase, also known as AMPK (Cell Metabolism, February 2007). This enzyme functions to increase mitochondria in muscles. Anything that reduces the number or efficiency of mitochondria interferes with your body's ability to burn fat and sugar for energy. As a result, blood sugar, fat and cholesterol levels rise. Most cells in your body contain many mitochondria, small furnaces that burn food for energy. With aging, the number and the efficiency of mitochondria both decrease. This interferes with your body's ability to turn food into energy. The extra calories that are not burned accumulate in your body as fat in your muscles, liver and fat cells. This causes you to gain weight. Extra fat in cells block their ability to take in sugar from the blood stream, so blood sugar levels rise and you are at increased risk for developing diabetes. Extra fat in the liver prevent the liver from removing extra insulin, so insulin levels rise to constrict arteries and cause heart attacks. Insulin also makes you hungry all the time to increase your chances of gaining weight.

AMPK is increased by exercise and by drugs used to treat diabetes, such as metformin or Actos. The best way to increase the number and size of mitochondria in your cells is to exercise. If you do not have a regular exercise program, you are shortening your life. How exercise strengthens mitochondria and prevents aging

The benefits reported in mice appear to apply to humans. For the last two years, Diana and I (ages 69 and 75) have been part of group of tandem bicycle riders, ages 40s to 70s, who race flat out for 25 to 30 miles three times a week and ride more than 100 additional miles in the rest of the week. All look younger, are thinner and more muscular, and are far more active than their same-age contemporaries in The Villages, Florida where we live.

Impotence Predicts Heart Attacks, Diabetes

Men who are impotent are at increased risk for heart attacks and diabetes. (Atherosclerosis, February 2011). The two most common causes of impotence are blood vessel disease (arteriosclerosis) or lack of the male hormone, testosterone. When a man lacks testosterone, he usually has little or no sexual desire. On the other hand, if he still has desire, his testosterone is usually normal but his blood vessels are usually damaged and the same damage that occurs in the penis also occurs in the arteries leading to his heart.

Lack of male hormones is strongly associated with increased blood levels of triglycerides and the bad LDL cholesterol that increase risk for metabolic syndrome, obesity, diabetes, high blood pressure and atherosclerosis. Giving testosterone to men deficient in that hormone lowers levels of triglycerides and the bad LDL cholesterol, and helps to slow the progression of blood vessel damage.

All men who have difficulty achieving erections need to get blood tests for diabetes (HBA1C), testosterone, prolactin (a hormone that causes impotence and is produced by a brain tumor), cholesterol and triglycerides, and have their blood pressure checked. Most of these men will have serious blood vessel damage from arteriosclerosis and will need a program that includes *losing weight if overweight, *starting a supervised exercise program, *restricting refined carbohydrates (sugared drinks and foods made from flour), fried foods and red meat, *increasing intake of fruits and vegetables, and *checking their vitamin D3 (should be greater than 75 nmol/L).

Men who need testosterone replacement should not take testosterone pills because they go from the intestines to the liver to lower the good HDL cholesterol and increase risk for heart attacks. They should use a route that bypasses the liver such as testosterone injections or testosterone gel that is rubbed on the skin.

Restrict Protein, Not Just Calories, to Prolong Life

Recent research show that protein restriction may be far more effective than calorie restriction in prolonging the lives of humans. Many studies show that restricting calories prolongs the lives of yeast, worms, spiders, flies, insects, rats and probably monkeys. Humans who severely restrict calories have long-life characteristics, such as low cholesterol and blood pressure and hearts that are more than 15 years younger than those of other North Americans their age (Experimental Gerontology, August 2007).

However, most of the test group of humans who restrict calories do not have a drop in a hormone called Insulin-Like Growth Factor-1 (IGF-1) that appears necessary for living a long time. High blood levels of IGF-1 are associated with premature aging and diseases of aging such as diabetes and cancer. IGF-1 levels are lower than normal in worms, flies and mice on restricted-calorie diets, but not in humans. This week a report shows that IGF-1 shortens life by increasing cell DNA genetic damage, and causes cancer by blocking apoptosis that causes cancer cells to kill themselves before they destroy their host (Science Translational Medicine, February 16, 2011).

Luigi Fontana, a professor of medicine at Washington University in St Louis, noticed that most calorie-restricting humans eat high levels of protein, about 1.7 grams per kilogram of body weight/day. This is more than the US government-recommended intake of 0.8 g/kg/day, and even higher than the 1.2 g/kg/day that the average American eats. Dr. Fontana asked humans on calorie restricted diets to reduce their intake of protein to 0.95 g/kg/day. After just three weeks of reduced protein intake, their IGF-1 levels dropped markedly (Aging Cell, September, 2008).

Among the calorie-restricting humans, vegans have lower levels of IGF-1 than meat-eaters (Rejuvenation Research, February 2007). Strict vegans also have significantly lower IGF-1 levels than people who restrict just calories, even if they are heavier and have more body fat. Strict vegans take in about 10 percent of their calories from protein, whereas those on calorie restriction tended to get 24 percent of calories from protein. Other data show that diets lower in protein might protect against some cancers. So restricting protein may be more important than restricting calories.

If fruit flies and rodents are fed special diets that restrict protein, they can eat as many calories as they want and still live longer (Nature, December 2009). This suggests that as long as you are not overweight, you may not need to restrict calories. Instead, restrict only protein which is far easier to do.

Furthermore, you can probably eat all the fruits and vegetables you want and not restrict calories as long as you restrict protein. That's very good news because it is far easier to restrict protein than it is to restrict all foods. The only way that you can restrict calories and still remain healthy is to eat a diet based on vegetables. It now appears that you extend your life far more by reducing protein that you would by restricting just calories.

Cycling Does Not Weaken Bones

A recent article from France may explain why some top bicycle racers have low bone densities, indicating an increased risk for breaking their bones (The Physician and Sportsmedicine, October 2010). Nobody has ever shown that bicycling or any other type of exercise weakens bones. I discussed this in detail in my 9/12/10 eZine.

We may now have an explanation for the weak bones found in some elite bicycle racers: they could have taken glucocorticoids to help them ride faster. These drugs, taken for just a few days, take calcium out of bones to cause low bone density, osteoporosis and bone fractures. Examples of glucocorticoids include Cortisone, Dexamethasone, Hydrocortisone, Prednisolone and Prednisone.

Female athletes who were not competitive bicycle racers were given 50 mg of prednisone per day for one week and then tested to see how long they could continue cycling at 75 percent of their maximal output (VO2max). They were able to last 66.4 minutes after a course of prednisone, compared to only 47.9 minutes after placebo (European Journal of Applied Physiology, November 2009). That's an incredible 30 percent increase in endurance time.

The limiting factor in how fast you can ride a bicycle or run, ski or skate over long distances is the time it takes for oxygen to get into your muscles. Therefore anything that decreases your need for oxygen will help you to move faster over distance. Sugar requires less oxygen than fat or protein to be converted to energy by your muscles. So anything that causes your muscles to burn more sugar, and less fat, makes you faster. Corticosteroids markedly elevate blood sugar levels. For example, a normal blood sugar is below 100. After taking steroids, your blood sugar can rise over 300.

Glucocorticoids, taken in pills or injections, are banned by the World Anti-Doping Agency (WADA) during competition. Athletes get around the rule restricting corticosteroids by claiming that they have *asthma treated with steroid inhalers, *certain skin disorders treated with steroid creams, or *muscle or joint injuries, immune disorders or diseases treated with steroid creams, pills or injections.

People should take glucocorticoids only if they need them to treat a serious, usually life-threatening disease. Not only can glucocorticoids cause permanent osteoporosis, they also can increase risk for diabetes, high blood pressure, heart attacks and fat gain. They are very different from the anabolic steroids that some athletes take to grow larger and stronger muscles.