We have all heard that calcium supplements help in the prevention of osteoporosis. Observational studies have also suggested that high calcium intake can protect against vascular disease. So it was quite surprising to hear about a recent 5-year study indicating that women who take calcium supplements might have excess risk for myocardial infarction (MI; JW Womens health Mar 2008, p. 17, and BMJ 2008; 336-262).
Other studies were evaluated looking at the relationship between calcium supplements without Vitamin D and cardiovascular risk in men and women over age >40. What was found was that the risk for heart attack rose by 31% in those participants receiving calcium supplements compared with those who received placebo. In those who had dietary sources of calcium <805 mg daily, calcium supplementation was NOT associated with risk for myocardial infarction.
Some things to think about:
Most calcium supplements in the U.S. also contain vitamin D, but the authors excluded trials in which calcium was combined with vitamin D. So we don’t know wether supplementing calcium with vitamin D was associated with excess risk for MI.
When eating foods containing less than 800 mg of Calcium and adding calcium supplementation, risk of MI did not increase.
Lastly, in none of the randomized controlled trials were the effects of calcium supplementation on cardiovascular disease statistically significant. So no conclusions can really be made.
Dietary calcium is preferable over supplementation. But if your dietary intake is <800 mg/day, then supplementation of the recommended amount (1000 mg daily for women aged 25-50; 1200-1500 mg daily for women >50) of calcium WITH vitamin D is advised.