An article released today in the Journal of the National Cancer Institute claims that calcium plus vitamin D supplementation is not associated with a reduced breast cancer risk, but my prima facie observations appear to reveal a crucial flaw.

The researchers evaluated breast cancer incidence in 36,282 post-menopausal women who were randomly assigned to take 1,000 mg of calcium plus 400IU of vitamin D daily or a placebo.

It turned out that the incidence of breast cancer was comparable between the two cohorts, with 528 and 546 cases, respectively.

They then thought it fit to conclude that “The main findings do not support a causal relationship between calcium and vitamin D supplement use and reduced breast cancer incidence”.

Observe this quote (from Wikipedia):

The 2005 Dietary Guidelines for Americans recommend that older adults, people with dark skin, and those exposed to insufficient ultraviolet radiation (i.e., sunlight) consume extra vitamin D from vitamin D-fortified foods and/or supplements.

Individuals in these high-risk groups should consume 25 micrograms (1000 IU) of vitamin D daily to maintain adequate blood concentrations of 25-hydroxyvitamin D, the biomarker for vitamin D status.

The Canadian Pediatric Society recommends 2,000 IU daily for pregnant and breastfeeding women.

This is to say that it remains possible that the women in the supplementation cohort were not even receiving minimum adequate levels of vitamin D, depending on their diets and exposure to sunlight.

Vitamin D is produced in the skin when exposed ultraviolet light. The amount of vitamin D the skin can produce in this manner can exceed 10,000 IU per day.

The 400 IU vitamin D supplementation would have been vastly outweighed by any number of lifestyle decisions, and could probably be considered ‘noise’ in the overall scheme of things.

I’m confident that this extremely lazy and irresponsible study can be safely ignored.

Adapted from materials provided by Eurekalert.