Vitamin D: Bones Are Just the Beginning

Vitamin D has long been linked to the prevention of bone diseases like osteoporosis and osteopenia, but D doesn't stop there. In an overdue spotlight of vitamin D, Andrew Weil has partnered with Walter Willett, M.D. chairman of the Department of Nutrition at the Harvard School of Public Health, to highlight the vitamin's other attributes.

Muscle weakness and falls. Vitamin D deficiency can lead to muscle weakness. A study of 4,000 adults aged 60 to 90 found that those with higher blood levels of vitamin D had stronger leg muscles and better mobility (American Journal of Clinical Nutrition, September 2004).

Cancer. Vitamin D may lower the risk of many cancers by regulating cell growth. Taking 1,000 IU of vitamin D a day can cut the risk of colon cancer by 50 percent and reduce the chances of breast and ovarian cancer by 30 percent (American Journal of Public Health, February 2006). Vitamin D from sunshine showed equally favorable results. A study of men in San Francisco revealed that those with the highest amount of sun exposure had half the risk of prostate cancer than those with little sun exposure (Cancer Research, June 15, 2005).

Cardiovascular health. Recent studies in Europe found that elderly people with low blood levels of vitamin D were more likely to have a stroke, and a German study suggests low levels of the vitamin may lead to the development of congestive heart failure (Journal of the American College of Cardiology, January 1, 2003).

Autoimmune diseases. Multiple sclerosis (MS) and other autoimmune disorders — in which immune responses are directed against the body's own tissues — are much less common near the equator, where people get more sunlight and produce more vitamin D.

Sure, vitamin D can be found in some foods and through sun exposure, but roasting on the beach is an ineffective method of absorbing the vitamin. Sunscreen prevents vitamin D from entering the body and baking without it, as we all know, can lead to skin cancer and premature aging. Weil approves of moderate sun exposure — 10 or 15 minutes without protection a few days a week — but still recommends supplementing. He suggests taking 1,000 IU of vitamin D a day.

How do you get your vitamin D?

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