Do swimmers need vitamins?

小臭贝

by Cindy Carroll

Many athletes take hefty dosages of vitamins and minerals, hoping to gain that elusive competitive edge. Taking supplements to improve one's performance has long been a popular practice. It seems pretty harmless, and who knows, it may take a second or two off a five hundred ... right? Sorry, research still shows no vitamin or mineral will specifically improve one's athletic performance unless you're deficient in the nutrient to start (and that includes all the hype about chromium). For example, if you're iron deficient, an iron supplement may help you swim faster and longer only because iron deficiency promotes too little oxygen to your muscles.

But how about taking supplements to boost your immune system? Now that may be a vitamin of a different color. It sounds less concrete, less specific than supplementing directly to improve performance, but research is showing some promising findings.

EXERCISE, IMMUNITY AND TISSUE DAMAGE

Supplementing with certain vitamins may help with recovery from longer exercise bouts. While moderate exercise has been linked to strengthening immunity, strenuous and endurance exercises greater than five hours per week has been argued to weaken immunity because of the increase in free radicals (substances known to alter and destroy cell DNA). Research shows that the increased oxygen consumed during strenuous exercise produces more of these "bad guy-free radicals."

William J. Evans, PhD, Director of the Noll Physiological Research Center at the Pennsylvania State University, states that "We can supplement the body's natural defenses with antioxidant nutrients to help neutralize the natural effect f free radicals on the body's cells and tissues." Evans' findings suggest that vitamin E and vitamin C may help prevent some of this tissue oxidation and decrease muscle soreness. Most of his research is with activities such as running but evans acknowledges that "exhaustive swimming can also produce muscle soreness and that swimmers too could benefit from vitamin E and vitamin C supplementation."

Additional findings from his studies suggest that other beneficiaries are individuals aged 55 and over and the "weekend warrior" athlete. He explains that "supplementation with vitamin E and perhaps other antioxidant nutrients may make older people respond to exercise related stress, more like a young adult." Apparently, Dr. Evans is not alone with his recommendations. Based on his and other research, the United States Olympic Committee has developed the following recommendations for antioxidant vitamin supplementation for athletes: three to 20 mg beta carotene, 250 to 1000 milligrams vitamin C and 100 to 400 IU vitamin E.

PROTEIN WITH CAUTION

Lest we forget, vitamins and minerals can be toxic if abused, especially minerals such as selenium, zinc and iron (mega-dosing is considered dosages at least 10 times the Recommended Dietary Allowances (RDA)). Furthermore, vitamins and minerals are a weakly regulated industry because the Food and Drug Administration does not treat them as drugs. Although vitamin E is largely thought to be safe even in large amounts, studies do show that people with a history of bleeding disorders including hemorrhagic stroke should check with their doctor first.

The minimum long term safe dosages of vitamins and minerals are still not clear. Any recommendation for a supplement should be based on your medical history since vitamins and minerals are influenced by medications and your current and past health status. Ask your physician or a registered dietitian for more information. A multivitamin with 100 percent of the RDA is acceptable and advisable for most people. This is the safest way to help you meet your nutrient needs while also giving you a bit more. Although, vitamin E and vitamin C supplementation may protect against exercise induced muscle damage, they have not yet been shown to specifically improve swimming performance.

FOOD STILL MOST IMPORTANT

A poor diet does not replace even the strongest of supplements. Nor does it replace a reckless lifestyle of smoking and inactivity. It's difficult to get suggested supplemental amounts of vitamin E by diet alone, considering that many Americans don't meet the RDA of vitamin E. Vitamin C is plentiful in many foods, but suggested amounts would also be challenging with diet alone. It's smart, however, to get a good dietary base regardless of supplementation.

What has become a common thread in the research with vitamin and minerals is that the people with the lowest incidence of diseases are those people that eat that greatest amounts of fruits and vegetables. Chances are, there are many ingredients in that orange that may prevent disease and possibly strengthen immunity. Some things never do change. Keep eating those fruits and vegetables and then some.

GOOD FOOD SOURCES OF IMMUNE FRIENDLY NUTRIENTS

Vitamin E sources: almonds, hazelnuts, peanut butter, salad/vegetable oils, sunflower seeds and wheat germs. Vitamin C sources: vegetables such as asparagus, broccoli, Brussels sprouts, cauliflower, cabbage, red and green peppers, kale, potatoes and tomatoes; fruits such as cantaloupes, grapefruits, honeydew melons, oranges, tangerines, strawberries, and kiwis.