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Extra dose of vitamin D may reduce risk of getting cancer

Sunshine vitamin may cut cancer risk

Date published: 7/1/2007

VITAMIN D and calci- um may reduce can- cer risks, according to an intriguing study out of Creighton University in Omaha, Neb.

You may have heard a bit about this news, and I want to tell you more and give you my take on what it means.

Scientists followed nearly 1,200 Nebraska women who were 55 or older. The women were randomly divided into three groups: one group took calcium supplements, another took calcium plus vitamin D and the third group took a placebo, or dummy pill.

Unexpectedly, scientists found that women taking calcium plus vitamin D for four years had much lower cancer rates than the other groups--more than four times lower. This applied to all kinds of cancers: breast, colon, lung, lymphoma, uterine and others.

The study is the first ever to show vitamin D supplements may reduce cancer risk. Scientists had long suspected this was the case but had been unable to prove it.

They had observed patterns showing that the farther people lived from the equator, the higher the rates of many cancers. The farther north you go in the United States, the less sunshine you are exposed to. Because sunlight on our skin produces vitamin D in the body, scientists wondered if vitamin D somehow protected against cancer.

However, only one other study looked at actually giving vitamin D supplements. That study, the Women's Health Initiative, gave the government-recommended 400 units of vitamin D daily and found no cancer protection.

The newer study, however, gave a much higher dose, 1,100 units of vitamin D-3, a form also called cholecalciferol. Scientists have been debating for years how much vitamin D is needed, with many saying that higher doses--2,000 units a day--are needed to boost the immune system.

Vitamin D overdoses are rare, but they are possible because the body stores extra vitamin D in fat cells. It doesn't purge unneeded vitamin D.

Medical problems like hyperpararthyroidism and certain cancers make some people hypersensitive to too much vitamin D, so it's necessary to be cautious.

It's hard to get enough vitamin D from foods; it's found in fatty fish, shiitake mushrooms and fortified milk. Mainly, the human body seems to have evolved to make vitamin D from a three-step chemical reaction caused when sunlight hits our skin.

Jennifer Motl is a registered dietitian. Formerly of Fredericksburg, she now lives in Wisconsin.

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Date published: 7/1/2007