Monday, March 31, 2008

Coconut Oil Does Not Make Frying Safe

The author of a popular natural health newsletter is selling coconut oil based on this claim. He is correct that frying with various oils causes carcinogens to form, but nobody has shown that coconut oil doesn't also form these same carcinogens.

Fats are classified by how many double bonds they have in their structures. Double bonds are the weak links in a molecule that break down with heating to form all sorts of harmful chemicals that increase cancer risk. Monounsaturated fats have only one double bond in each fatty acid. Polyunsaturated fats have more than one double bond. Since saturated fats have no double bonds, and all the others have double bonds, saturated fats are more stable and less like to break down to form heterocyclic amines. Plant sources that are high in saturated fats include coconut, palm and palm kernel oils. Animal-source frying oils such as clarified butter are also high in saturated fats.

However, they all break down with burning and high-temperature frying. You should not burn any fats. If you enjoy deep-fried foods, keep them as occasional treats; don't believe that using any particular type of oil will make them healthful. More on fried foods

Friday, March 28, 2008

High Fructose Corn Syrup is No Worse than Sugar

You may have heard that the obesity epidemic in America is caused by high fructose corn syrup (HFCS) found in most sugared drinks and many types of foods. However, the evidence now blames any sugar in drinks and not the high fructose corn syrup in particular.

Researchers in the Netherlands showed that beverages sweetened by HFCS do not affect energy levels, appetite-related hormone levels or obesity any more than milk or drinks sweetened with sucrose. People did not eat more food after drinking HFCS beverages than they did after drinking milk or non-HFCS sodas. They also showed that the obesity hormones (insulin, ghrelin, glucose and glucagon-like peptide 1 or GLP-1) were affected similarly by all types of sweetened drinks. Journal reference

A sucrose-sweetened beverage contains 64 per cent glucose and 36 per cent fructose, while the HFCS is 41 per cent glucose and 59 per cent fructose, a not very significant difference. The researchers concluded that "energy balance consequences of HFCS-sweetened soft drinks are not different from those of other iso-energetic drinks: a sucrose soft drink or milk." Currently, many scientists believe that any sugar in drinks promotes obesity because sugar in liquid form does not fill you up to make you eat less in the same way that sugar in solid food does. If you want to lose weight, I recommend that you exercise more and eat less, and avoid sugar in liquid form. More on HFCS

Thursday, March 27, 2008

Cramps Probably Caused by Muscle Damage

Even though muscle cramps are extremely common in athletes and exercisers, we really do not know what causes them. Nobody has shown consistent benefit 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.

Known medical causes of muscle cramps are extremely rare in athletes. These include narrowed blood vessels, usually from atherosclerosis; compression of nerves, low thyroid function, or side effects of medications such as diuretics. Some cramps are caused by low mineral or fluid levels. However, for the vast majority of people 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 mineral levels as those who did not get muscle cramps. Cramping during exercise usually occurs in healthy people without any underlying disease or known cause. Journal reference

I think that the most common cause of exercise- associated cramps is damage to the muscle itself. Before you get a cramp, you will probably feel that 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.

You may be able to prevent cramps by exercising more frequently but less intensely and for shorter periods of time, but most serious exercisers do not want to do this. There is some evidence that taking sugared drinks and foods during prolonged exercise helps maintain endurance and muscle integrity which helps prevent cramps. So take a source of sugar every 30 minutes or so during a vigorous workout, and back off if you feel a group of muscles pulling and tightening during exercise. Most exercisers just accept that occasional cramps will occur and cause no long-term harm.

Tuesday, March 18, 2008

Fast Eater? Slow Down!

An interesting study from Japan suggests that eating fast is a risk factor for diabetes. Researchers at Nagoya University Graduate School of Medicine in Aichi studied middle-aged men and women and found that the faster a person ate, the more likely he or she was to be fat (Preventive Medicine, February 2008). Furthermore, both insulin levels and blood sugar levels were higher in people who ate faster. High insulin and blood sugar levels are markers for being diabetic or at risk for developing type II diabetes.

Before insulin can do its job of driving sugar into cells, it must first attach to special hooks on the surface of cells called insulin receptors. As a person gains weight, excess fat blocks insulin receptors so they cannot drive sugar into cells. Blood sugar levels rise and the pancreas responds by putting out large amounts of insulin. Insulin makes you ever fatter by acting on your brain to make you hungry and it acts on the liver to make even more fat and on the fat cells in your belly to pick up and store that extra fat. Early diabetes is characterized first by high insulin levels, then by storing fat in the belly, rather than the hips. Eventually the pancreas exhausts itself and stops making insulin completely, and person then must take insulin. More on insulin resistance

Monday, March 17, 2008

Bone Density Does Not Necessarily Measure Bone Strength

The greater the force you put on your bones during exercise, the stronger they become. Researchers at the University of Missouri in Columbia showed that recreational runners have denser bones than cyclists (Journal of Metabolism, February 2008). Another study from Université de St-Etienne in France show that youth soccer players have an increase in bone density over three years of playing high level soccer (Joint Bone Spine, January 2008). They failed to show that the soccer players had denser bones than their classmates, yet their intuition told them that heavy forces on bones while playing soccer must strengthen bones, so they stated that "The yearly gain in bone density is greater in soccer players than in controls."

These studies and many others comparing various sports measure bone density, not bone strength. The only way to measure bone strength is to see how much force it takes to break them. Needless to say, nobody is doing these studies in humans. So scientists use bone density, which can be measured, as a substitute for measuring bone strength. Nobody has shown that bone density determines bone strength. For example, birds have bones that are not dense because they need a low weight to fly effectively. Yet their bones are very strong. I think that, in the future, methods will be developed to determine bone strength and they will show that measuring bone density is, at best, a crude measure of whether a person is likely to break his or her bones. More

Sunday, March 16, 2008

Sexual Activity or Exercise: Which Stresses the Heart More?

The stress on the heart from making love is relatively insignificant, compared to that caused by exercising, according to a study from the University of Medicine and Dentistry of New Jersey in New Brunswick. Nineteen men and thirteen women performed a maximal-effort stress test (exercising vigorously on a treadmill) followed by home-monitored sexual activity using heart rate and blood pressure recording devices. During sexual activity the men had maximum heart rates 28 percent lower than during exercise, and systolic blood pressure 20 percent lower. In the women the heart rate was 36 percent lower and blood pressure 25 percent lower. Journal reference

The duration of treadmill exercise slowed by nine seconds for each additional year of age, and duration of sexual activity slowed by one minute for each year of age. How long they could make love correlated with how long they could run on a treadmill. For each additional minute on the treadmill, the person could make love for an additional 2.3 minutes. More

Friday, March 14, 2008

Competitive Sports for Children?

Today, if you want your children to be champion athletes, they need to start training at a young age and play their sport 12 months a year. So naturally you want to know if heavy athletic training before and during the period of rapid growth in children will harm then in any way. The most common concern is whether heavy training will make them shorter as adults or damage the growth plates in their bones. Researchers at the University of Saskatchewan studied young gymnasts, swimmers and tennis players and showed that participation in these sports does not shorten their adult height. Furthermore it did not affect the age when they entered puberty. Journal reference

The biggest concern about starting training this early is not physical, it's whether you will destroy a child's desire to play that sport after you have taken away his or her childhood. Children as young as five years old are shipped off to Florida where they have private tutors and play tennis for several hours a day. Young football players are encouraged to take supplements. Gymnasts work out for six hours a day and are told to restrict calories. Try not to be one of those parents or coaches who place athletic training above the child's best interests.

Thursday, March 06, 2008

Weight Gained When You Stop Exercising May Be Hard to Lose

If you want to use exercise to help control your weight, don't stop. Paul Williams of the University of California at Berkeley showed that interrupting an exercise program can cause you to gain weight that won't come off easily even after you resume training (Medicine & Science in Sports & Exercise, February 2008).

Williams compared 17,280 men and 5,970 women who decreased their running distances with 4,632 men and 1,953 women who increased their running distances over an eight year period. He found that runners who decreased their distance from five to zero miles per week gained four times as much weight as those who decreased their distance from 25 to 20 miles per week. He also found that people who started running after an exercise layoff didn't lose weight until their mileage exceeded 20 miles per week in men, and 10 miles per week in women.

The people in the lower mileage groups were not able to lose the weight gained during time off if they just resumed the same exercise regimen. This study explains why exercise programs designed to prevent obesity may fall short if the exercise is irregular, seasonal, or often interrupted. "Many scientists attribute the obesity epidemic to excess calories rather than [lack of] exercise, because dieting has been shown to produce more weight loss than exercise," says Williams. "My findings suggest that calorie intake and body weight may be self regulating in active individuals." More on exercise and weight control