Does Vitamin D Prevent Breast Cancer?

Breast cancer incidence and mortality appear not to be associated with vitamin D supplementation

(RxWiki News) Vitamins and minerals tend to go through popularity stages. Fish oil has been all the rage. Now it’s being called into question. Vitamin E has had a similar fate. Scientists recently focused on vitamin D and breast cancer prevention.After reviewing two studies involving thousands of women, Italian researchers suggest that vitamin D supplements do not help prevent breast cancer.

They admit, though, that these findings aren’t firm.

One integrative oncologist questioned the design of this recent research, along with its conclusions.

"Talk to your doctor about vitamins and supplements."

Maddalena Barba, PhD, a researcher at the Regina Elena National Cancer Institute of Rome, Central Italy, led this review and analysis of randomized controlled trials.

The goal of the meta-analysis (review of previous studies) was to determine the effect of vitamin D supplementation on breast cancer incidence (rates).

Participants in the two studies that the researchers analyzed were randomly assigned to take vitamin D or a placebo (sugar pill). One study enrolled 5,292 people and the other included 1,180 individuals.

In the larger study, participants were assigned to take either 800 IU of vitamin D3, 1000 milligrams of calcium, both supplements or a placebo (fake supplement) for 24 to 62 months. For the second study, study members took either placebos or 1,400 to 1,500 milligrams of calcium and 1,000 IU of vitamin D3.

Neither study found an association between vitamin D supplementation and lower incidence of breast cancer.

This study's senior author, Antonio Giordano, MD, PhD, of the Sbarro Institute for Cancer Research and Molecular Medicine and Center of Biotechnology at Temple University in Philadelphia, said in a prepared statement, that "...vitamin D supplementation seems not to be associated with a reduced risk of breast cancer development in women.  However, the scientific panorama related to the association of interest is still limited and overall inadequate to draw firm conclusions."

dailyRx News spoke with integrative oncologist Brian D. Lawenda, MD, clinical director of Radiation Oncology at 21st Century Oncology in Las Vegas, about this study. "Breast cancer, as with the majority of cancers, takes many years to develop,” Dr. Lawenda said. “Looking for a risk reduction effect by analyzing data from short-term nutrient intervention studies completely misses the point."

He added that supplementing with vitamin D3 for less than five years " likely too short to both detect any cancer risk reduction and deliver an adequate anti-cancer benefit."

Dr. Lawenda, who is founder of, described the dosing of vitamin D as "...quite meager (800-1000 IU/day), considering the minimum RDA [recommended daily allowance] is 600-800 IU/day."

“Finally, this meta-analysis tells us nothing about whether patients had adequate vitamin D levels (25-hydroxyvitamin D) during their supplementation. This is important information to know, as many adults require significantly higher doses of vitamin D3 to reach a healthful level of this important nutrient,” said Dr. Lawenda, who was not involved in the study.

“As an integrative oncologist, I always recommend obtaining readings of 25-hydroxyvitamin D levels at baseline and during supplementation to help guide safe and effective supplementation,” he said.

This study was published July 22 in PLOS One.

Italian Medicines Agency (AIFA) supported this research. No conflicts of interest were disclosed.

Review Date: 
July 31, 2013