Older women who take calcium supplements to maintain healthy bones could be increasing their risk of heart attacks, according to research.
The new study, published on bmj.com (British Medical Journal), adds to mounting evidence that calcium supplements increase the risk of cardiovascular events, particularly heart attacks, in older women.
These are often prescribed to post-menopausal women to maintain bone health but the authors of the research suggest their use in managing osteoporosis should now be reassessed.
The new research, led by Professor Ian Reid at the University of Auckland, New Zealand, 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.
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