Vitamins and Minerals from A to Zinc

Wednesday, July 22, 2009

ROCHESTER, Minn. — Vitamin supplements offer important nutrition but may not ward off serious illnesses such as cancer or heart disease. That's just one of the research findings covered in the Special Report on Vitamins and Minerals, a supplement to the July issue of Mayo Clinic Women's HealthSource. The Special Report covers information and issues related to vitamins and minerals, including when supplements are needed, highest safe doses and research on benefits and risks.

Some findings include:

Vitamin B-3 (niacin): Niacin helps the body convert food to energy and helps improve circulation and cholesterol levels. Researchers have found that, in high doses, niacin can reduce low-density lipoprotein (LDL or "bad" cholesterol) and triglycerides and raise high-density lipoprotein (HDL or "good") cholesterol. However, the doses needed for these effects, usually greater than 1,000 milligrams (mg) per day, can cause liver damage. High doses of niacin should be considered a prescribed medication and taken only under a doctor's supervision.

Vitamin C: Studies have shown that eating food high in vitamin C can lower rates of cancer and heart disease. It's unclear whether vitamin C supplements provide the same benefits.

Studies have shown that vitamin C supplements, taken with some other antioxidants and zinc, may slow the progress of age-related macular degeneration. However, there's little evidence that vitamin C prevents colds or lessens cold symptoms.

Vitamin D: It's called the sunshine vitamin because the body can produce it when exposed to sunshine. Yet, an increasing number of Americans are deficient in vitamin D.

It's been well established that adequate vitamin D and calcium can prevent or slow osteoporosis and reduce bone fractures. New research highlights other potential benefits of vitamin D, including reducing the risk of muscle pain and weakness, autoimmune disorders (such as rheumatoid arthritis and multiple sclerosis), cardiovascular disease and certain cancers.

The U.S. government recommends adults get anywhere from 200 to 600 International Units (IU) of vitamin D a day, depending on age. With new knowledge about the benefits of vitamin D, many experts now say that intake should be at least 800 to 1,000 IU a day.

Vitamin E: Vitamin E is an antioxidant that protects red blood cells and may play a role in the body's immune function. It's long been thought that diets rich in antioxidants, such as vitamin E, could help lower the risk of some cancers and heart disease. Recent studies suggest that vitamin E supplements don't provide the same health benefits as dietary sources do and may even by harmful to health. High-dose vitamin E supplements may increase the risk of health failure or death.

Patients should talk to their care providers about vitamin supplements, their benefits and risks, and recommended doses.

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