High calcium intake in men not women is associated with all-cause mortality risk: Melbourne Collaborative Cohort Study
The risk of mortality associated with high dietary calcium is uncertain. Unlike a highly publicised study in Swedish women, high dietary calcium intake in men—not women—was associated with increased all-cause mortality.
The association of dietary calcium with mortality is controversial. A study of women from the Swedish Mammography Cohort (SMC) suggested higher calcium was associated with higher mortality risk, whilst a study of Australian adults from the Melbourne Collaborative Cohort Study (MCCS) suggested higher intakes were associated with lower mortality risk. Thus, we aimed to perform a sex-specific re-analysis of the MCCS to evaluate the association of dietary calcium with mortality outcomes and directly compare hazard estimates (95% confidence intervals) in women with those from the SMC.
A prospective cohort study of community-dwelling Australian adults was conducted, in which 34,627 individuals (women 20,834 (60.2%); mean ± SD, age = 54 ± 8 years) were included at baseline after excluding those with prevalent cardiovascular (CV) disease, cancer or incomplete data. Energy-adjusted dietary calcium was categorised into the following levels of consumption (mg/day): < 600, 600–999, 1000–1399 and ≥ 1400. Mortality from all-causes, any cardiovascular disease and myocardial infarction was determined. Mortality hazards relative to intakes were estimated to be of 600–999 mg/day.
In women, hazard estimates for calcium intake of ≥ 1400 mg/day did not reach significance for all-cause (HR = 0.85; 0.66, 1.10) or CV (HR = 1.10; 0.69, 1.81) mortality in adjusted models. In men, intakes of ≥ 1400 mg/day were associated with a 42% increased all-cause mortality risk (HR = 1.42; 1.02, 1.99). There was a trend toward increased CV mortality (HR = 1.83; 0.94, 3.55).
Contrary to findings from a similar study conducted in Swedish women, Australian women, after adjustment for cofounders showed no increase in mortality risk with high calcium intakes possibly reflecting differences in calcium handling dynamics, diet or lifestyle factors between the two countries. We identified an increased risk for men.
KeywordsCalcium All-cause mortality Cardiovascular disease Diet Cohort study
AJR obtained the data, performed all the analyses, prepared the tables and figures and wrote the manuscript. DS reviewed the analyses and contributed to the manuscript drafting. BK, AH, DE and GG contributed to the manuscript drafting. BA proposed the topic, reviewed the analyses, contributed to the manuscript drafting and provided intellectual input in the project development. PRE proposed the topic, reviewed the analyses, contributed to the manuscript drafting and provided intellectual input in the project development. All authors reviewed the final draft.
Compliance with ethical standards
Conflicts of interest
The MCCS cohort recruitment was funded by VicHealth and Cancer Council Victoria. The MCCS was further supported by Australian NHMRC grants 209057, 251553 and 504711 and by infrastructure provided by Cancer Council Victoria. Cases and their vital status were ascertained through the Victorian Cancer Registry (VCR) and the Australian Institute of Health and Welfare (AIHW), including the National Death Index and the Australian Cancer Database. Alexander J. Rodriguez is supported by an Australian Government Research Training stipend. David Scott is supported by a National Health and Medical Research Council R.D. Wright Biomedical Career Development Fellowship (GNT1123014). Belal Khan, Allison Hodge, Dallas English, Graham G. Giles, Bo Abrahamsen and Peter R. Ebeling declare that they have no conflict of interest.
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