How do calcium and vitamin D supplements affect women's deaths from heart disease and cancer?

A recent study found that calcium and vitamin D supplements can reduce cancer deaths for women who have reached menopause.

However, the study also found disappointing results, suggesting that this combination of supplements could increase deaths from cardiovascular disease (CVD) after more than 20 years of follow-up.

Cynthia Thompson, MD, of the Mel and Enid Zuckerman School of Public Health at the University of Arizona in Tucson, and colleagues examined long-term health outcomes among postmenopausal women in the Women's Health Initiative trial, which included 36,282 participants with no history of cancer. Breast or colon and rectum.

Participants were randomly assigned to receive 1,000 mg of calcium carbonate with 400 IU of vitamin D3 daily or a placebo.

The researchers found that after a follow-up of 22.3 years, women who were randomized to treatment with calcium and vitamin D experienced a 7% reduction in cancer deaths, and a 6% increase in deaths from cardiovascular disease, compared to the placebo group.

No overall effect was observed on other measures, including all-cause mortality.

There was significant variation in cancer incidence estimates when taking into account whether participants reported using supplements before randomization into the test, while no difference was observed in mortality estimates, with the exception of deaths from cardiovascular disease.

Thompson's team doesn't know for sure what's driving this increase in heart disease deaths, but they suspect the difference may be due to calcium supplements encouraging more calcification in the coronary arteries.

“The effects of vitamin D supplements for cancer prevention may depend on achieving blood vitamin D concentrations above 50 nmol/L,” the researchers wrote. “Given the method used in the study, we were unable to separate additional benefits or harms of supplements containing calcium and vitamin D combined.” "versus vitamin D alone, which is a topic worthy of future study."