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Vitamins C and E pack a punch in moderation

November 14, 2000

Vitamins C and E pack a punch in moderation



Vitamins C and E are known for their role as antioxidants, helping mop up cell-damaging free radicals in the body.

How much of these important nutrients do you need on a daily basis? Do you need to take a supplement?

In the past, nutrient recommendations for vitamins C and E were based on preventing deficiency diseases. For vitamin C, 60 milligrams were recommended daily for men and women. For vitamin E, recommendations were 8 milligrams per day for women and 10 milligrams per day for men.

The Food and Nutrition Board of the National Academy of Sciences recently increased its recommendations for these two nutrients to promote their antioxidant role. At the same time, it set "tolerable upper intake levels" as a guide to how much is too much.

For years, researchers have sought to understand the role of antioxidants in reducing the risk of chronic disease. Many studies have shown a link between diets rich in foods containing antioxidants, such as fruits and vegetables, and lower incidence of certain chronic diseases. However, a direct link is unclear. Studies have shown that antioxidants can prevent or counteract cell damage that stems from oxidative stress. The leap to prevention has yet to be made. Taking large amounts of some antioxidants can cause health problems.

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So how much of these nutrients do you need each day without running into toxicity problems? The Food and Nutrition Board's new recommended dietary allowances (RDA) for vitamin C are 90 milligrams for men and 75 milligrams for women. Smokers should take in an extra 35 milligrams per day to compensate for the high level of oxidative stress and cell damage associated with cigarette smoke. These recommendations can be easily met on a diet that regularly includes one or more of the following foods: citrus fruits, strawberries, broccoli, potatoes, peppers and leafy green vegetables.

The board set 2,000 milligrams of vitamin C per day, from both food and supplements, as the upper tolerable level. Taking more can cause diarrhea in some people. The body will most likely excrete any unused intake above the RDA.

The vitamin E RDA for both men and women is 15 milligrams daily through foods. Vegetable oils like canola and olive oil, wheat germ and soybeans are great sources. Other sources include unprocessed cereal grains, nuts (especially almonds, peanuts, pistachios, walnuts), fruits, vegetables, and meats, especially the fatty portion.

The forms of vitamin E in supplements are not as usable as those in foods. For supplements, the above recommendations translate to 22 International Units (IUs) for d-alpha-tocopherol, sometimes labeled as "natural" vitamin E on supplements, and to 33 IUs for dl-alpha-tocopherol, a synthetic version. Supplements can help ensure that the diet meets the recommendations for vitamin E. Of the two supplement forms, the "natural" d-alpha-tocopherol is absorbed faster than other synthetic forms and is more likely to contain a mix of tocopherols.

The upper level for vitamin E is 1,000 milligrams from food and supplement sources. Consumption above that is strongly discouraged. High levels of vitamin E can have anticoagulant effects and the associated risk of hemorrhagic damage.

As with all recommended dietary intake of vitamins, your best choices will be healthful foods rather than supplements.

Lynn F. Little is a family and consumer sciences extension educator for Maryland Cooperative Extension, Washington County. Maryland Cooperative Extension programs are open to all citizens without regard to race, color, sex, disability, age, religion or national origin.

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