What did the media say?
The media reported that calcium supplements may increase the risk of myocardial infarction (MI) in older women, contrary to previous suggestions that they had a protective cardiovascular affect.
What did the research show?
Researchers carried out a five year study involving 1,471 postmenopausal women with a mean age of 74. Half were randomised to receive calcium supplements – two 200 mg tablets before breakfast and three in the evening – and the remainder to placebo.
After adjustment, they found MI was more common in the calcium group – 24 events in 21 women – than in the placebo group – 10 events in 10 women. A combined end-point of MI, stroke, or sudden death was also more common in the calcium group – 61 events in 51 women – than the controls – 36 events in 35 women.
They calculated the number of women needed to treat for five years to cause one MI was 44, one stroke was 56 and one cardiovascular event was 29. By comparison the number needed to treat to prevent one symptomatic fracture was 50.
What did the researchers say?
The authors, from Auckland University, said: ‘That calcium supplementation might have adverse effects on vascular disease incidence is of concern because the morbidity and mortality that would follow from even a small adverse effect on vascular event rates is such that the beneficial effects of calcium supplementation on bone loss would be rapidly counterbalanced.’
What does this mean for nursing practice?
Judy O’Sullivan, cardiac nurse at the British Heart Foundation, said that, because the study disagreed with previous findings, further research was needed before any change in advice was made.
‘Anyone who has been advised by a health professional to take calcium supplements to protect their bones should not stop doing so in light of this study alone without medical advice,’ she said.
BMJ Online First (2008) www.bmj.com