Calcium supplements, up to 1000 mg/day, and increased dietary intake of calcium may be associated with reduced risk of mortality in women, according to new research published in the Journal of Clinical Endocrinology & Metabolism.

Other studies have raised concerns about adverse risks associated with calcium, which is often recommended for bone health along with vitamin D. Some clinical studies suggest that calcium intake may be cardioprotective, whereas others report increased risk associated with calcium supplements. Both low and high serum levels of 25-hydroxyvitamin D have been associated with increased mortality, researchers noted.

The purpose of this study was to determine the association between total calcium and vitamin D intake and mortality and heterogeneity by source of intake. The Canadian Multicenter Osteoporosis Study cohort is a population-based longitudinal cohort with a 10-year follow-up (1995–2007).

This study included randomly selected community-dwelling men and women; a total of 9,033 participants with non-missing calcium and vitamin D intake data and follow-up were studied.

Total calcium intake (dairy, nondairy food, and supplements) and total vitamin D intake (milk, yogurt, and supplements) were recorded. The outcome variable was all-cause mortality.

There were 1,160 deaths during the 10-year period. For women only, researchers found a possible benefit of higher total calcium intake, with a hazard ratio of 0.95 (95% confidence interval, 0.89–1.01) per 500-mg increase in daily calcium intake and no evidence of heterogeneity by source; use of calcium supplements was also associated with reduced mortality, with hazard ratio of 0.78 (95% confidence interval, 0.66–0.92) for users vs. non-users with statistically significant reductions remaining among those with doses up to 1,000 mg/day. These associations were not modified by levels of concurrent vitamin D intake. No definitive associations were found among men.

Researchers found no evidence of mortality benefit or harm associated with vitamin D intake.