Men who have a high intake of supplemental calcium may be at an increased risk for cardiovascular disease (CVD) death, report researchers.
On the other hand, women with a high intake do not appear to be at any increased risk, they say.
Additional studies are needed to investigate the effect of supplemental calcium use beyond bone health and also to confirm whether there is a gender difference in the cardiovascular effect of calcium supplementation, say Qian Xiao (National Cancer Institute, Bethesda, Maryland, USA) and team.
The findings come from a prospective analysis of 388,229 individuals, aged 50-71 years, who completed a baseline food-frequency questionnaire in 1995-1996 as part of the National Institutes of Health-AARP Diet and Health Study. The questionnaire included items about the frequency and dosage of individual's supplemental calcium intake from both individual calcium supplements and multivitamins.
Using the the National Death Index to follow up participants for cause of death, the team found that 7904 and 3874 CVD deaths occurred in 219,059 and 169,170 of the men and women, respectively, over a mean period of 12 years.
As reported in the Archives of Internal of Medicine, calcium intake was associated with a significantly elevated risk for total CVD and heart disease mortality among the men. Compared with men who did not take calcium supplements, those with a supplemental calcium intake of more than 1000 mg/day had a significantly increased risk for total CVD death, at a relative risk (RR) of 1.20 and, specifically, for heart disease death, at a RR of 1.19. This level of intake however, did not significantly increase the risk for cerebrovascular disease death among the men.
In contrast, supplemental calcium intake was not associated with deaths from total CVD, heart disease, or cerebrovascular disease among the women, reports the team.
"The sex difference is intriguing," say Xiao et al. "However, we cannot rule out the possibility that supplemental calcium intake may be associated with cardiovascular mortality in women."
The team points out that a recent study found that more than 50% of older men and almost 70% of older women in the USA take calcium supplements.
"Given the extensive use of calcium supplement in the population, it is of great importance to assess the effect of supplemental calcium use beyond bone health," conclude the researchers.
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