US researchers recruited 388,229 men and women aged 50 to 71 years and followed them up for an average of 12 years. Their dietary intake was assessed with a self-administered questionnaire, which asked about frequencies and dosage of any calcium supplements taken. Frequency was split into never, less than once per week, one to three times per week, four to six times per week and every day.
Men that took 1000 mg/d of calcium supplements had a significant 20% increase in the risk of cardiovascular disease death, and 19% increase in the risk of heart failure death, compared with non-users. No association between cardiovascular disease mortality and calcium supplementation was found in women.
What does it mean for GPs?
The authors concluded that ‘given the extensive use of calcium supplement in the population, it is important to assess the effect of supplemental calcium use beyond bone health.’