Increased Vitamin D Levels May Help Prevent Cancer Development

Women given vitamin D3 and calcium supplements had a 30% lower risk of cancer.

New research suggests that upping vitamin D levels may lower the risk of developing cancer.

In a 4-year study published in the Journal of the American Medical Association, investigators found that women who received vitamin D3 and calcium supplements had a 30% lower risk of cancer.

The study included 2303 healthy postmenopausal women who were 55 years and older from 31 counties in Nebraska. Participants were randomized to receive either 2000 IU of vitamin D3 and 1500 mg of calcium, or identical placebos daily for 4 years.

The vitamin D3 dose was approximately 3 times the recommended dietary allowance of 600 IU for adults through age 70 years, and 800 IU for those 71 and older.

The results of the study showed that women who received vitamin D3 and calcium supplements had a 30% lower risk of cancer compared with women administered the placebo.

Although the difference in cancer incidence rates between the groups did not quite reach statistical significance, in further analyses, blood levels of vitamin D—–specifically 25-hydroxyvitamin D (25(OH)D)––were significantly lower in women who developed cancer during the study than in the participants who remained healthy.

At baseline, the average (25(OH)D) level in the participant’s blood was 33 ng/mL, which was higher than the usual target levels that currently range from 20 ng/mL to 23 ng/mL. The findings suggest that higher vitamin D levels than the currently recommended dose are needed to substantially decrease the risk of cancer.

“This study suggests that higher levels of (25(OH)D) in the blood are associated with lower cancer risk,” said principal investigator Joan Lappe, PhD, RN. “The study provides evidence that higher concentrations of (25(OH)D) in the blood, in the context of vitamin D3 and calcium supplementation, decrease risk of cancer.

“These results contribute to a growing body of scientific findings, including results of a similar randomized controlled clinic trial preceding this one in Nebraska women, that indicate that vitamin D is a critical tool in fighting cancer. It is also of value in preventing other diseases, according to previous research.”

Most cells in the body require vitamin D to function properly, and without adequate vitamin D, the normally functioning cells can convert to malignant cells, according to Lappe.

“While people can make their own vitamin D3 when they are in the sun near midday, sunscreen blocks most vitamin D production,” Lappe said. “Also, due to more time spend indoors, many individuals are lacking adequate levels of vitamin D compounds in their blood. The results of this study lend credence to a call for more attention to the important of vitamin D in human health and specifically in preventing cancer.”