After more than 20 years of follow-up, a study found that postmenopausal women who took calcium and vitamin D (CaD) supplements had an increased risk of cardiovascular disease (CVD) and a decreased risk of malignancy.

In the Women’s Health Initiative CaD trial, which included 36,282 women without a history of breast or colorectal cancer, Cynthia A. Thomson, Ph.D., R.D., from the Mel and Enid Zuckerman College of Public Health at the University of Arizona in Tucson, and colleagues looked at the long-term health outcomes among postmenopausal women. A placebo or 1,000 mg of calcium carbonate plus 400 IU of vitamin D3 per day was given to participants at random.

The women who were randomly assigned to receive CaD versus placebo showed a decrease in cancer mortality (hazard ratio: 0.93) and an increase in CVD mortality (hazard ratio: 1.06) over a median cumulative follow-up of 22.3 years, according to the researchers. All-cause mortality and other indicators showed no overall effect. When stratified by participants’ reported usage of supplements before to randomization, there was significant heterogeneity in the estimates of cancer incidence, but no variation was detected in the estimates of death, with the exception of CVD mortality.

“Effects of vitamin D supplementation for cancer prevention may depend on achieving serum vitamin D concentrations above 50 nmol/L,”. “Given the study design, we could not disentangle the added benefit or harms of supplementation with CaD in combination versus vitamin D alone, a topic worthy of future study.”