Vitamin D Cuts Cancer Risk: Study

Mar. 23 -- FRIDAY, June 8 (HealthDay News) -- Boosting your vitamin D intake can dramatically reduce your risk of breast and other cancers, a new study found.

The research adds to growing evidence that vitamin D can help protect against many forms of cancer as well as other diseases, Creighton University researchers said.

But an American Cancer Society spokeswoman urged caution in interpreting the findings, saying it was premature to recommend taking vitamins to reduce cancer risk.

Joan Lappe, a Creighton University professor of medicine and nursing and lead author of the study, said, "What we can say from our study is that 1,100 international units (IUs) a day of vitamin D definitely decreased the incidence of cancer."

That amount of the vitamin is nearly triple the recommended intake for the age group studied -- women who were 55 and older when the four-year study started.

Lappe's team followed 1,179 study participants who were all postmenopausal and lived in rural Nebraska. The women were free of known cancers for the 10 years before entering the study. They were assigned to one of three groups and followed for four years.

One group took 1,400 to 1,500 milligrams of supplementary calcium a day, another group took that same amount of calcium plus 1,100 IUs of vitamin D daily, while the third group took placebo pills every day.

After four years, those in the combination vitamin D and calcium group had a 60 percent lower risk of developing cancer, compared to the placebo group. The calcium-only group had a 47 percent reduced risk.

Then the researchers eliminated data from the first year of the study, figuring some women may have entered the study with cancer that had not yet been diagnosed. The results were more dramatic, Lappe said.

When the researchers looked at results from just the last three years of the trial, they found the combination calcium-and-vitamin D group had a 77 percent reduced risk of cancers, compared to the placebo group. The risk for the calcium-only group was essentially unchanged.