Calcium supplements raise CVD mortality in men

Taking calcium supplements appears to raise the risk of death from cardiovascular disease among men but not women, a study has shown.

In contrast, the intake of dietary calcium has no apparent effect on cardiovascular disease (CVD) mortality in either sex, said the division of cancer epidemiology and genetics, National Cancer Institute.

These findings from a large prospective study that followed 388,229 adults for 12 years are not definitive but provide further support for the controversial idea that supplemental calcium may have adverse effects on cardiovascular health. However, calcium also “is widely involved in many aspects of human physiology” and is known to benefit some aspects of cardiovascular health, such as lowering blood pressure and improving lipid profiles, so further study is warranted.

“Given the extensive use of calcium supplements .... It is of great importance to assess the effect of supplemental calcium use beyond bone health,” they used data from the National Institutes of Health-AARP Diet and Health Study, which assessed adults who were aged 50-71 years in 1995 and lived in California, Florida, Louisiana, New Jersey, North Carolina, Pennsylvania, Atlanta, and Detroit. For this study, the researchers followed 219,059 men and 169,170 women participants, correlating their calcium intake at baseline with cumulative mortality from heart disease, cerebrovascular disease, and other forms of CVD.

A total of 23% of the men and 56% of the women took calcium supplements, and 56% of the men and 58% of the women took multivitamins containing calcium. During follow-up there were 7,904 CVD deaths in men and 3,874 in women.

The use of calcium supplements correlated with a significantly elevated risk of total CVD mortality, heart disease mortality, and cerebrovascular disease mortality in men. In addition, men taking the highest quintile of calcium supplementation showed an increased risk of CVD death, which was mainly driven by heart disease death.

In women, null associations were seen between calcium supplements and all of these outcomes.

Dietary calcium showed no relationship with any mortality outcome in men or women.

These findings remained robust in a sensitivity analysis that excluded data on all deaths that occurred during the first 2 years of follow-up.

In analyses that categorized subjects by age, smoking status, body mass index, hypertension, hypercholesterolemia, magnesium intake, and alcohol consumption, the positive association between calcium supplements and increased mortality persisted in most of these subgroups among men. It remained null among women except in three subgroups: in former smokers, women who did not have hypertension, and those with hypercholesterolemia, calcium supplements were linked to an increase in CVD mortality.

One mechanism by which Calcium supplements could exert an adverse effect on CVD is the deposition of calcium phosphate in CV structures in the form of vascular calcification. Increase blood coagulation and arterial stiffness also have been linked to high serum calcium le’vels, the researchers noted.