Could a high blood level of calcium increase a person’s risk for a heart attack? That question arose after studies showed that people taking high-dose calcium supplements appear to be more likely to experience a heart attack or a stroke (de Abajo et al, Journal of the American Heart Association, May 18,2017; Tankeu, Ndip Agbor & Noubiap, Journal of Clinical Hypertension, June 2017).
A Naturally High Blood Level of Calcium:
Epidemiologists from Sweden and the UK analyzed data from more than 180,000 individuals whose genetic data had been determined. Those with genetic variants (SNPs) leading to a naturally high blood level of calcium were about 25 percent more likely to develop heart disease or have a heart attack compared to people with normal calcium levels.
Larsson, Burgess & Michaelsson, JAMA, July 25, 2017
Here are a few of the earlier reports that led scientists to look on a high blood level of calcium with suspicion.
Calcium Supplements Linked to Heart Attacks:
An analysis in the British journal BMJ called into question both the safety and effectiveness of taking a calcium supplement. The scientists reviewed data from 15 randomized placebo-controlled trials, each with at least 100 subjects. They found that people assigned to take calcium were nearly 30 percent more likely to have a heart attack than those taking placebo pills. The difference was significant (Bolland et al, BMJ, July 29, 2010).
Although the increase is not great, so many people take calcium tablets that the overall number of excess heart attacks could be quite high. Worse, people are taking this risk for questionable benefit.
Many expect the calcium they take to keep their bones strong. It is not clear, however, that calcium supplements are effective at preventing fractures. Apparently about 40-odd people would have to take calcium for five years to prevent one additional broken bone.
The researchers suggested that the role of calcium supplementation should be re-evaluated. Getting calcium from food, however, did not appear to be a problem and was recommended by the investigators.
Women Are Also at Risk from Excess Calcium:
Calcium supplements might increase both men’s and women’s risk of dying from heart disease. The National Institutes of Health-AARP Diet and Health Study tracked more than 200,000 men for more than a decade. Those who took 1,500 mg of calcium daily were at elevated risk for cardiovascular disease and death.
A separate study from Sweden confirmed there is also a risk for women. The researchers followed more than 60,000 women for nearly two decades. Those who consumed 1,400 mg of calcium daily in their diet and also took a calcium pill more than doubled their risk of dying during the study. This evidence added to a growing body of data suggesting that long-term high-dose calcium supplements may be doing more harm than good (Michaelsson et al, BMJ, Feb. 13, 2013).
