YOUR HEALTH
RALLIE MCALLISTER, M.D.
RELEASE: SATURDAY, SEPTEMBER 1, 2007

Boosting Vitamin D Intake Reduces Cancer Risk

 Daily doses of a single vitamin could dramatically reduce your risk for several types of cancer. A growing body of scientific evidence suggests that vitamin D is a powerful cancer preventive agent.

In laboratory studies, vitamin D deters the growth of cancer, preventing the out-of-control cell division that makes it such a dangerous disease. In humans, higher blood levels of the vitamin have been linked to lower rates of cancer of the prostate, breast and colon.

In a landmark study conducted earlier this year at Creighton University School of Medicine in Omaha, Neb., vitamin D was found to play a major role in breast cancer prevention. The four-year study followed more than 1,000 healthy postmenopausal women.

The women were randomly assigned to one of three treatment groups. The first group received daily doses of supplemental calcium, the second group took a combination of calcium and vitamin D, and the third group received placebo pills.

The results of the study were impressive. Women who took daily doses of calcium plus 1,100 International Units (IU) of vitamin D experienced a 60 percent reduction in breast cancer risk compared to the women taking the placebo.

For women already diagnosed with breast cancer, vitamin D may slow the progression of the disease. In 2006, researchers at the Imperial College of London measured blood levels of vitamin D in 279 women with invasive breast cancer.

The disease was in its early stages in 204 of the women; and in advanced stages in the remaining 75. Vitamin D levels were significantly higher in the women with early stage disease than in women whose breast cancer had progressed to an advanced stage.

Adequate intakes of vitamin D have long been associated with reductions in the risk of colorectal cancer. A recent study at Harvard School of Public Health revealed that men with low blood levels of vitamin D were significantly more likely to develop colon or rectal cancer than those with higher levels.

In the August edition of the journal Nutrition Reviews, researchers at the University of California, San Diego, reported that an estimated 150,000 cancers of the colon and breast could be prevented each year in the U.S. if Americans simply increased their intake of vitamin D. The scientists advocated a dose of 2,000 IU per day for a meaningful reduction in cancer risk.

Currently, the Institute of Medicine recommends a daily vitamin D intake of just 200 IU for folks younger than 50; 400 IU for adults 51 to 70 years of age; and 600 IU daily for those over the age of 70. Based on the results of recent research demonstrating the positive effects of higher doses, it is highly likely that these guidelines will change substantially in the coming years.

In the meantime, most of us could benefit from a boost in vitamin D intake. Although the vitamin can be found in a few foods including salmon, fortified milk and breakfast cereals, it' s difficult to satisfy the body' s requirements through diet alone.

In the presence of ultraviolet rays from the sun, your skin is capable of manufacturing vitamin D. In some cases, getting just 10 to 15 minutes of sun exposure twice a week can help you maintain adequate blood levels of the vitamin. 

If you' re trying to steer clear of skin cancer, you' re probably slathering yourself with sunscreen or staying indoors during the sunniest times of day. Both practices interfere with your skin' s production of vitamin D and can increase the likelihood of a deficiency.

Your age, ancestry and the latitude at which you live can also influence your body' s ability to convert sunlight into vitamin D. Production of the vitamin is lower in older adults, individuals with dark skin and folks who live in northern areas.

To reap all the cancer-protecting benefits of vitamin D, many nutrition experts now recommend taking a daily supplement of at least 800 IU. According to the Institute of Medicine, the safe upper limit of vitamin D is 2,000 IU.
The latest research reveals that not all forms of vitamin D are equally beneficial.

Vitamin D-3, also known as cholecalciferol, is derived from animal sources. It' s been shown to be far more potent than Vitamin D-2, or ergocalciferol, which is derived from plant or fungal sources.

When it comes to reducing cancer risk, there' s no substitute for a nutritious diet, regular exercise, and avoiding smoking. If you' re looking for a little extra protection, a daily dose of vitamin D-3 may be your best bet.

Rallie McAllister, M.D., M.P.H., is a family physician in Kingsport, Tenn., and author of "Healthy Lunchbox: The Working Mom's Guide to Keeping You and Your Kids Trim." Her Web site is http://www.rallieonhealth.com. To find out more about Rallie McAllister, M.D., and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate Web page at www.creators.com.

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