New study finds link between Vitamin D and breast cancer survival

Is increasing the survival rate of  breast cancer as easy as taking a walk in the sun or taking a cod liver oil pill?

A new study suggests that women who don’t get enough Vitamin D are at greater risk of dying from the disease.

The study, published recently in the journal JAMA Oncology, looked at 1666 women with breast cancer whose average age was 58.7 and found that higher serum 25-hydroxyvitamin D levels were independently associated with better outcomes, including overall survival rates.

“Overall, we found a 30 percent reduction of all-cause mortality associated with vitamin D levels at the time of diagnosis,” said the study’s lead author Song Yao, an Associate Professor of Oncology Department of Cancer Prevention and Control at the Roswell Park Cancer Institute in Buffalo.

Foods such as mushrooms, oily fish, and tofu are all high in Vitamin D. It is also naturally produced by the human body upon exposure to sunlight.

This is not the first time science has found a link between Vitamin D levels and breast cancer, but to date there have been no randomized controlled trials conducted on the subject.

A randomized controlled trial is considered the most rigorous form of determining a cause/effect relationship because all patients are unaware of which treatment they have been given, and all participants have the same chance of being assigned to each of the study groups. But randomized controlled trials can present ethical issues because researchers may be knowingly exposing often fragile patients to an inferior treatment.

One breast cancer expert, Dr. Wendy Chen from Boston’s Dana-Farber Cancer Institute, says the new JAMA Oncology study just isn’t enough to prove a direct link between Vitamin D and breast cancer survival rates.

“I would not be able to derive a causal relationship from this data, because of all the things that are related to vitamin D and survival,” she told GMA News Online.

But for the time being, is there any real downside to any woman upping her Vitamin D intake?

The daily recommended intake for adults is 800 international units (IU) and the “Tolerable Upper Intake Level” is 4000 IU. That quite a range, but experts say there is really no risk of taking too much Vitamin D unless you ingest 50,000 IUs for several months on end. Even at that level Vitamin D toxicity is extremely rare because the body has mechanisms to deal with too much Vitamin D from foods or sunlight. As a result, the only way you can be exposed to Vitamin D toxicity is through supplements.

According to the Canadian Breast Cancer Foundation, there is a one in 30 probability a Canadian woman will die from breast cancer, making it the most common cancer diagnosis for women here. But things are improving, mostly due to public education about early detection. The incidence of breast cancer peaked in 1987, but is down 44 per cent since then.

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