William Penn Life, 2001 (36. évfolyam, 1-12. szám)
2001-02-01 / 2. szám
Nutritional overload? Why vitamin supplements may be too much of a good thing from The Associated Press WASHINGTON - Call it vitamania. About 40 percent of Americans pop vitamin pills. But just how much of each vitamin does your body need? When does food provide enough? And how much is too much? The Institute of Medicine has just updated national guidelines on how much of every vitamin and mineral Americans should eat daily for good health. It also released a never-beforecompiled list of which popular mega-dose vitamins could harm us. But consumers will be hard-pressed to use the guidelines to make more nutritionally savvy food and supplement purchases. Don't expect food labels to be updated with the new "recommended dietary allowances" any time soon. The Food and Drug Administration hasn't begun considering whether to force vitamin bottles to list the safe upper doses. It may take questioning a dietitian to learn that more than 1,000 milligrams a day of vitamin E-or 1,500 international units-could cause uncontrolled bleeding. Or that many people over age 50 have trouble absorbing vitamin B12 from natural food sources and thus should eat fortified foods, or take a daily supplement to ensure they get 2.4 micrograms a day. Or that the amount of vitamin D older people need for strong bones has doubled to 400 international units. The good news: Once you learn how many nutrients you need, an Agriculture Department Internet site quickly shows how much you're eating. Munched a handful of almonds? The web site~xvww.nal.usda.gov/fnic/ foodcomp—reveals that 7.5 milligrams of vitamin E, half a day's supply in a single snack. The Institute of Medicine, a private science organization that sets the nation's RDAs for nutrients, spent four years reviewing the scientific research into vitamins and minerals. Between 1997 and January 2001, it issued four reports, hundreds of pages each, determining the proper dose of each to optimize health and how much could cause side effects. Consider vitamin C: Women need 75 milligrams a day, men 90. Smokers should add another 35 milligrams. But more than 2,000 milligrams a day can cause diarrhea. Dietitians are devouring the reports. But, no one has issued a consumer-friendly list. Today's food labels are based on RDAs set in 1968. The FDA won't begin steps to add new vitamin numbers until the institute issues another report next year on how much protein, fat and fiber we also should eat. Many RDAs haven't changed a lot. So nutritionists say a healthy daily diet, with at least five fruits and vegetables, can provide plenty of most vitamins. More important: Until FDA updates vitamin supplement labels, nobody will know safe upper doses, even as sales of multivitamins with three times the RDA and larger "megadose" supplements rage. Consider vitamin A. Enough—900 micrograms a day for men, 700 for women~is important for good vision and immune function. But more than 3.000 micrograms daily can risk birth defects in pregnant women, and liver damage for others. Yet many vitamin supplements are sold in "international units," very confusing because how to convert IUs into micrograms and milligrams differs from nutrient to nutrient. For vitamin A, the guidelines say a microgram equals 3.33 international units—so a popular megadose of 10.000 units hits the daily safety limit. Another big question is how consumers with special needs will leam their new recommended doses, such as older people who should pay attention to vitamins B12 and D. Even updated food labels probably won't have enough space to tell them. What's a consumer to do? First, think about what you're eating. Try to get most vitamins from food and take only supplements your body really needs. People who don't eat much dairy, for instance, may need calcium supplements. Alternatively, using a regular multivitamin with 100 percent of RDAs "is sensible," says nutritionist Bonnie Liebman of the consumer group Center for Science in the Public Interest. "But remember taking the multivitamin is no excuse for eating a lousy diet.," she stresses. [M] Health Links For more information about vitamins and the new standard of “Dietary Reference Intakes,” log onto the web site of the Institute of Health: O www.iom.edu Click on “Recent Reports.” The press releases are easy-to-read summaries of the reports’ findings. Milliam Penn Lile, February 2001 5
