When you exercise in hot weather, you sweat and lose a lot of salt. That doesn't mean that you need to take salt tablets. The use of salt tablets is recommended only if their benefits exceed their side effects.
If you lose more salt than you take in, your muscles will start to hurt and cramp. You will feel tired and sick and develop a headache. You can even pass out. Taking salt tablets would replace the lost salt; however, they have side effects. They can irritate your stomach lining and make you throw up, and they can thicken your blood enough to cause clots in your arteries.
If you exercise regularly in the heat and your body starts to run out of salt, your sweat glands will produce sweat that is extremely low in salt. Americans eat way too much salt anyway. Almost all prepared food is loaded with it. Manufacturers know that salt makes food taste good, so they add large quantities to foods. The average American needs only about 200 milligrams of salt per day but takes in more than 3,000.
If you become weak and tired when you exercise in hot weather, stop exercising and check with your doctor. If you're low on salt, add some to your food and don't resume exercising until you feel good again.
Q: What do you think about the recent reports that pesticide residues are harming children?
A: A 1992 Food and Drug Administration report found that 40 percent of grains, 51 percent of fruits and 32 percent of vegetables contain pesticide residues. These values are all within federally allowed limits, and there are no reports that children have actually been harmed by them. Still, the size of children's bodies increases their risk for nerve damage and cancer by even a small amount.
The panel appointed by the National Academy of Sciences recently recommended that the government develop tests to see how harmful thepesticides are and to set more severe limits on the amount of pesticide residues that should be allowed in produce.
For now, you can reduce the concentration of pesticides in produce by as much as 99 percent by washing and peeling fruits and vegetables before you eat them. The Clinton administration has promised to try to reduce the use of high-risk pesticides and legislate the development of safer pesticides.
Incidentally, a study done by the attorney general of New York state found higher pesticide levels in so-called "organically grown" produce than in much cheaper non-organic produce sold in most supermarkets.
Q: I was told that my chronic fatigue might be caused by Lyme disease. What can I do?
Lyme disease is curable when treated early, but it may not be curable in its late stages. The classic early signs and symptoms of Lyme disease are fever, muscle aches and a "bull's eye" rash at the site of a tick bite. If you have Lyme disease at this stage, you can be cured by taking antibiotics, ampicillin or doxycycline for three weeks.
However, more than 10 percent of people with Lyme disease may not develop the telltale rash, and their symptoms may not be distinguishable from most other summer infections. Furthermore, the most commonly used tests for Lyme disease )) are not standardized enough to be completely dependable. The fever and muscle aches may go away, only to return months or years later as a chronic-fatigue-like syndrome. The symptoms can include joint and muscle pain, weakness, lethargy and nerve and brain damage, which may be characterized by loss of feeling or muscle control, unexplained pain or even bizarre behavior.
The treatments for late-phase Lyme disease often do not cure the muscle, joint and nerve symptoms.
Dr. Mirkin is a practicing physician in Silver Spring specializing in sports medicine and nutrition.