milk, eggs, cancerA vitamin found in milk, eggs, and fish could play a big role in preventing cancer. A new study in the journal Nutrition and Cancer finds that people who increase their intake of vitamin D might reduce their risk of colorectal cancer by as much as 30 percent.

“Vitamin D may be an important factor in colon cancer prevention, and is a potentially modifiable [risk] factor,” says lead study author Loren Lipworth, ScD, senior epidemiologist at the International Epidemiology Institute in Rockville, Maryland.

Lipworth and her colleagues conducted a large-scale study in six areas of Italy. They collected health and diet information via face-to-face interviews with 1,953 patients who had colon or rectal cancer, and compared them to 4,154 non-cancer patients from the same hospital.

The more vitamin D patients got through diet, the lower their risk of colon cancer, the researchers discovered. People with the highest dietary vitamin D intake (more than 4.29 micrograms a day) had a 30 percent lower risk of colon cancer than people with the lowest intake. The benefit was more pronounced among women than men.

Vitamin D didn’t appear to have any significant effect on lowering rectal cancer risk. The reason for this remains unknown.

The specific location of the colon cancer seemed to affect how well vitamin D reduced risk. Although about two-thirds of colorectal cancers are in the transverse and descending colon, this study found that vitamin D had more of a protective effect on cancers located in the ascending colon.

The evidence seems to suggest that vitamin D may lower colon cancer risk, although Lipworth cautions that several large studies, including randomized trials, have not found the same association. Also, in the past, many other single nutrients failed to live up to their cancer-preventing potential.

Still, vitamin D is worth incorporating into your diet for its many other known health benefits, including bone strength. Eggs, cheese, fish, and fortified dairy products are all good dietary sources. Vitamin D is also produced in sun-exposed skin (but limit your time outside or put on sunscreen after about 20 minutes to reduce your skin cancer risk). Experts say that getting 1,000 IU a day of vitamin D may help reduce colon cancer risk, although no “optimal” dose has been established.

Despite the increasing evidence that vitamin D might help prevent certain types of cancer, more than half of Americans still aren’t getting enough of the nutrient. Boosting our collective vitamin D intake might ultimately help prevent 250,000 colorectal cancer cases worldwide each year, the study authors say. If you are interested in taking vitamin D speak to your licensed healthcare practitioner.

Lipworth L, Bender TJ, Rossi M, Bosetti C, Negri E, Talamini R, et al. Dietary vitamin D intake and cancers of the colon and rectum: A case-control study in Italy. Nutrition and Cancer. 2009;60:70-75.

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