Vitamin may cut cancer risk

OMAHA, Neb. – Building hope for one pill to prevent many cancers, vitamin D cut the risk of several types of cancer by 60 percent overall for older women in the most rigorous study yet.

The new research strengthens the case made by some specialists that vitamin D may be a powerful cancer preventive and most people should get more of it. Experts remain split, though, on how much to take.

“The findings … are a breakthrough of great medical and public health importance,” declared Cedric Garland, a prominent vitamin D researcher at the University of California-San Diego. “No other method to prevent cancer has been identified that has such a powerful impact.”

While the most reliable yet, the study does have drawbacks. It was designed mainly to monitor how calcium and vitamin D improve bone health, and the number of cancer cases overall was small, showing up in just 50 patients.

Earlier research has shown that vitamin D helps regulate cell growth, a fundamental biological process that goes haywire in cancer.

This study, published today in the American Journal of Clinical Nutrition, is the first time researchers significantly boosted – and measured – blood levels of vitamin D and then followed identical groups of patients from start to finish.

That’s why, despite its modest size, the research was generating excitement. Nearly all other work has compared disparate groups of patients.

The researchers at Creighton University in Omaha focused on 1,179 seemingly healthy women with an average age of 67. The women were divided into three groups: 446 got calcium and vitamin D3 supplements, a similar number got calcium alone, and 288 took dummy pills.

The research team gave 1,000 daily international units of vitamin D, more than current guidelines calling for 200 to 600 units depending on a person’s age.

The researchers intended to check mainly for the effects of calcium on bone health. Their interest in cancer risk was secondary.

But the lower cancer risk stood out. Only 13 women, or 3 percent, developed cancer over four years of calcium and vitamin D supplements. With calcium alone, 17 women, or 4 percent, got cancer. With dummy pills, cancer appeared in 20 women, or 7 percent.

That shows a 60 percent lower cancer risk over four years in the group taking both supplements, compared with patients taking placebos. And when the first-year cancers were excluded – the ones mostly likely present before the study began – the findings were stronger still: a 77 percent lower risk for the combo group.

Still, people should consult their doctors before boosting their vitamin dosage, several experts warned. More study is needed to determine if the effects in this study hold true for large groups of people and men as well as women.