Dietary Supplements: What You Need to Know (cont.)

For people who can't eat regular food because of illnesses, these products are good alternatives. Still, "eating a wide variety of nutrient-rich foods is better, if tolerated," says Grotto.

And what about weight management? Using a meal replacement can help control calories and be beneficial, experts say -- as long as it's part of a lifestyle that includes exercise and a calorie-controlled diet.

Dietary Supplement No. 3: Sports Nutrition Supplements

This is a broad category that includes both sports performance and weight loss supplements. It includes pills, powders, formulas and drinks formulated not just to hydrate but to enhance physical activity. Among them are creatine, amino acids, protein formulas, and fat burners.

"These products provide a subtle, incremental effect. You can't use a sports supplement for a week and expect to gain pounds of muscle, but if used properly, research shows they can provide a slight, not overwhelming, edge," says Andrew Shoa, PhD., vice president for regulatory affairs for the Council for Responsible Nutrition, a trade association for the dietary supplement industry.

Kris Clark, PhD, RD, sports nutrition director at Penn State University, says she very carefully uses select sports supplements with collegiate athletes: "I rely on the major nutrients in food, timing of meals and fluids to enhance athletic performance, and in general I discourage dietary supplements, other than the use of sport shakes, bars, and gels after practice or events for muscle cell recovery."

She also uses chocolate milk, which she says is "the perfect recovery drink that includes protein, carbohydrates and fluids."

"Creatine is one of the most popular supplements, with over 100 studies consistently showing it can work in muscle cell recovery in athletes who engage in high-intensity, short-burst activity such as sprinting or weight lifting," notes Clark. "But it does not work for endurance or recreational athletics." (She cautions anyone taking creatine to be sure they stay well hydrated to avoid cramping.)

Stimulants are also common ingredients in sports supplements, says Shao. "Some products that contain stimulants like caffeine have been shown to be a performance enhancer," he says. "But it is not a panacea and must be part of a healthy diet and fitness routine."

Clark prefers to get these benefits from caffeinated drinks instead. "You can get the same boost from a cup of coffee or an energy drink that are safe. ... When you take supplements, there are often cryptic ingredients that could be potentially risky."

Dietary Supplement No. 4: Calcium

Calcium is one of the minerals most often lacking in Americans' diets. But experts say that whenever you can, you should choose calcium from foods such as dairy products, fortified foods, dark leafy greens, soybeans, beans, fish, and raisins.

The 2005 U.S. Dietary Guidelines recommends three servings of low-fat or non-fat dairy each day to help bridge this gap. But there are plenty of people who shun dairy, the best source of calcium in our diets.

"Many people misinterpret a sensitivity to lactose and think they are lactose-intolerant," says Grotto.

If you have not been diagnosed as lactose-intolerant, give dairy another chance. Start slowly, with a small amount with meals, or try dairy products that are lower in lactose, such as aged cheeses and yogurt.

If you do choose a calcium supplement, look for calcium citrate or lactate. These forms are best absorbed by the body, says Grotto.

Dietary Supplement No. 5: B vitamins

B vitamins include thiamin, niacin, riboflavin, pantothenic acid, vitamin B-6, and vitamin B-12.

Many of us don't need these supplements, experts say.

"Romance surrounds the B vitamins because people misuse them to reduce stress and think a supplement will make them a nice person in traffic," says Grotto. "But there is not much research to support this theory. And besides, our diets are plentiful in B vitamins."

One exception, he says, is seniors, who may need additional B-12 because as we get older, we absorb less of it. Most of us should skip the supplements and get our Bs from grains, dark green vegetables, orange juice, and enriched foods. People with certain medical conditions or who take drugs that interfere with vitamin absorption may also require supplementation.

Dietary Supplement No. 6: Vitamin C

Vitamin C is often taken in an effort to ward off colds, though there's little proof this works.

"There is scant evidence it may decrease the intensity or duration of colds, but it won't do any harm up to about 1,000 milligrams a day," Grotto says. Because it is a water-soluble vitamin, excess amounts are excreted.

Your health-care provider may tell you to take vitamin C if you have a wound that's healing. But wound otherwise, go for food sources. Rich sources include oranges, peppers, grapefruits, peaches, papayas, pineapples, broccoli, strawberries, tomatoes, and melons.

Dietary Supplement No. 7: Glucosamine and Chondroitin

These supplements are often taken by people with joint pain.

In a study published in the Feb. 23, 2006, issue of The New England Journal of Medicine, these supplements, taken alone or in combination, were not found to provide significant relief from osteoarthritis knee pain among all participants. However, results in a subgroup of study participants with moderate to severe pain showed the combination may be effective.

While the evidence is not conclusive, some rheumatologists say many of their patients find relief from the combination.

"About 40% of my osteoarthritis patients benefit from taking 1,500 mg of glucosamine and 1,200 mg chondroitin sulphate a day (for) four to eight weeks," says Kaiser Permanente rheumatologist Eduardo Baetti. But "most patients are also taking pain relievers, such as Tylenol."

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