A recent study addressed that question, noting that “supplementation may affect chronic disease in older women, evidence of long-term effects on health outcomes is limited.”
To remedy the situation, University of Arizona Tucson researchers and colleagues sought to evaluate long-term health outcomes among postmenopausal women in the Women’s Health Initiative CaD trial. Their results were published in Annals of Internal Medicine.
The post hoc analysis was a long-term postintervention follow-up of the 7-year randomized intervention trial of CaD. The trial occurred in 40 centers across the United States and involved 36,282 postmenopausal women with no history of breast or colorectal cancer.
Participants 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 study team tracked incidence of colorectal, invasive breast, and total cancer; disease-specific and all-cause mortality; total cardiovascular disease (CVD); and hip fracture by randomization assignment (through December 2020). In addition, they stratified analyses on personal supplement use.
The results indicated that for women randomly assigned to CaD versus placebo, a 7% reduction in cancer mortality was observed after a median cumulative follow-up of 22.3 years (1,817 vs. 1,943 deaths; hazard ratio [HR], 0.93; 95% CI, 0.87-0.99), along with a 6% increase in CVD mortality (2,621 vs. 2,420 deaths; HR, 1.06; 95% CI, 1.01-1.12).
“There was no overall effect on other measures, including all-cause mortality (7,834 vs. 7,748 deaths; HR, 1.00 [CI, 0.97 to 1.03]),” the authors reported. “Estimates for cancer incidence varied widely when stratified by whether participants reported supplement use before randomization, whereas estimates on mortality did not vary, except for CVD mortality.”
The study team cautioned that hip fracture and CVD outcomes were available only on a subset of participants, and effects of CaD versus joint supplementation could not be disentangled.
“Calcium and vitamin D supplements seemed to reduce cancer mortality and increase CVD mortality after more than 20 years of follow-up among postmenopausal women, with no effect on all-cause mortality,” the researchers concluded.
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