Older women who take calcium supplements are more likely to have a heart attack, according to new research.
The research, led by professor Ian Reid at the University of Auckland, New Zealand, supports similar findings in earlier studies.
Women are often prescribed the supplements to maintain healthy bones but researchers claim their use in managing osteoporosis should now be reassessed.
The new study has been published on bmj.com (British Medical Journal)
The new research follows the Women’s Health Initiative (WHI) study - a seven-year trial of more than 36,000 women which found no cardiovascular effect of taking combined calcium and vitamin D supplements.
But the majority of participants in that study were already taking personal calcium supplements, which may have obscured any adverse effects.
Prof Reid’s study looked at data from 16,718 women who were not taking personal calcium supplements at the start of the trial.
It found that those allocated to combined calcium and vitamin D supplements were at an increased risk of cardiovascular events, especially heart attack.
But women who were taking personal calcium supplements at the start of the trial, combined calcium and vitamin D supplements did not alter their cardiovascular risk.
The authors said they suspect abrupt changes in blood calcium levels after taking a supplement causes the adverse effect, rather than it being related to the total amount of calcium consumed.
- Bolland MJ, et al. Calcium supplements with or without vitamin D and risk of cardiovascular events: reanalysis of the Women’s Health Initiative limited access dataset and meta-analysis. BMJ 2011; Advance online publication