Several recent scientific studies show that protein supplements do not help athletes to become stronger or develop larger muscles.
Fifteen years ago the Federal Trade Commission held hearings and concluded that the proteins in supplements have no properties over protein contained in regular food that would help them to make muscles larger or stronger.
The protein supplement manufacturers responded by making "free form" amino acids and selling them for a higher price. The scientific data show that adding acid to protein to separate the amino acids offers nothing, since your stomach and intestines do that anyway. Then the promoters made the claim that specific amino acids -- arginine, ornithine and lysine -- raise growth hormone levels, which makes muscles larger and stronger.
In the September 1993 issue of the International Journal of Sports Nutrition there are three articles showing that these amino acid supplements do not affect insulin, testosterone, cortisone or growth hormone levels; they do not make athletes stronger; and they do not build larger or stronger muscles.
Protein supplements are taken from foods such as milk, tuna and soybeans. No process has been devised by man that can make a protein extract derived from food that is more effective in building muscles than the food itself.
Q: I want to start exercising but I'm afraid it will hurt my heart.
A: Check with your doctor. Heart specialist Paul Dudley White stated that "exercise can't hurt a healthy heart" and no one has proved him wrong. You become tired during exercise because your muscles feel tired. A healthy heart can withstand all the exercise you can give it.
There are two reasons for muscle fatigue: lack of fuel and lack of oxygen. Skeletal muscles use both fat and sugar for energy. When skeletal muscles run out of their stored sugar called glycogen, they can't contract and function adequately. They hurt and you will find it difficult to coordinate them.
Heart muscle uses fat and sugar carried in your bloodstream plus a breakdown product of metabolism called lactic acid. It's almost impossible for the heart muscle to run out of fuel, and it's also impossible for a healthy heart to run out of oxygen.
Oxygen is carried to the heart in the bloodstream through arteries on the heart's outside surface. If these arteries are not plugged up with plaques, they are large enough to supply all the oxygen that your heart can possibly need. However, if you have something blocking your arteries, such as fatty plaques, your heart may not get enough blood and can hurt and start to beat irregularly.
Q: My HDL cholesterol is very low and my doctor told me not to worry, but I thought HDL helps prevent heart attacks. Should I be taking medication?
A: If you are on a low-fat diet, you may not need to worry about a low HDL. HDL cholesterol is healthful because it carries cholesterol from the bloodstream to the liver, where it can be processed and removed from the body. The test for HDL cholesterol measures only the balance between how much HDL is being produced and how much is being removed. Anything that increases liver production of HDL is good because the more HDL you make, the more efficiently you can remove cholesterol from your bloodstream.
Even though women in China generally have very low blood levels of HDL, they have a very low incidence of heart attacks. Their low-fat diets, which consist mostly of vegetables, enable their livers to efficiently remove cholesterol from their bloodstreams with very low HDL levels. American women, however, may have heart attacks despite having high HDL levels. This is because their diets are so high in fat that they produce more cholesterol than their livers can successfully process and eliminate.
Dr. Mirkin is a practicing physician in Silver Spring specializing in sports medicine and nutrition.