Calcium supps double chances of heart attack

Women aged over 55 years given calcium supplements to combat osteporosis raised their chances of a heart attack by almost 50% and increased risk of stroke by one third, according to data published in the British Medical Journal on January 15.

A team of New Zealand researchers randomized 1,471 postmenopausal women with a mean age of 74 to 1g calcium supplementation or placebo. Over the five years of the evaluation, myocardial infarction was more commonly reported in the calcium group than in the placebo arm (45 events in 31 women versus 19 in 14 women, p=0.01). The composite endpoint of MI, stroke or sudden death was also more common in the calcium group (101 events in 69 women vs 54 in 42 women, p=0.008).

After adjudication, MI remained more common in the calcium group and, for the composite endpoint, 61 events were verified in 51 women in those on supplements and 36 events in 35 women in the placebo group. When unreported events were added from the national database of hospital admissions in New Zealand, the relative risk of MI was 1.49 (0.86 to 2.57) and that of the composite endpoint was 1.21 (0.84 to 1.74). The respective rate ratios were 1.67 (95% confidence intervals 0.98 to 2.87) and 1.43 (1.01 to 2.04). Event rates in the calcium cohort totaled 23.3 per 1,000 person years vs 16.3 per 1,000 person years.