Calcium, vitamin D may affect long-term health in postmenopausal women
A post hoc analysis of data from the Women's Health Initiative found that those who took calcium and vitamin D supplements had a lower risk for death from cancer and a higher risk for death from cardiovascular disease.
Calcium and vitamin D (CaD) supplements were associated with decreased risk for death from cancer but increased risk for death from cardiovascular disease (CVD), a study found.
Researchers conducted a post hoc analysis of a randomized trial from the Women's Health Initiative (WHI) that compared calcium and vitamin D supplements with placebo. The goal of the analysis was to evaluate long-term health outcomes after 20 years of follow-up among postmenopausal women. Overall, 36,282 women with no history of breast or colorectal cancer were randomized 1:1 to 1,000 mg of calcium carbonate (400 mg of elemental calcium) with 400 IU of vitamin D3 daily or placebo. The researchers looked at incidence rates of cancer, disease-specific and all-cause mortality, CVD, and hip fracture. The analysis was published March 12 by Annals of Internal Medicine.
Women who were randomly assigned to take CaD supplements had a 7% lower risk of dying from cancer over 22.3 years compared to those taking placebo (1,817 vs. 1,943 deaths; hazard ratio [HR], 0.93; 95% CI, 0.87 to 0.99). However, there was also a 6% higher risk of dying from CVD among those who took the supplements (2,621 vs. 2,420 deaths; HR, 1.06; 95% CI, 1.01 to 1.12).
The study didn't find any significant overall effect on other measures, including all-cause mortality. The authors noted that cancer incidence seemed to depend on whether the women were already taking supplements before the study began and that CVD mortality was higher among those taking the supplements. They also encouraged caution in interpreting results because of multiple comparisons and said that some observations may be due to chance; for example, women reporting no supplementation differed from women those who did on several demographic and health behavior characteristics. The influence of CaD supplements on cancer could be attributed partially to these characteristics and not solely to personal supplement use, they said.
"Overall, these analyses suggest the possibility of a delayed effect of CaD supplementation in reducing cancer mortality among postmenopausal women, as well as the possibility of an increase in CVD mortality with no net effect on all-cause mortality," the authors wrote.