Calcium supplements boost myocardial infarction risk

Myocardial infarction or heart attack was more commonly found in patients with osteoporosis who used calcium supplements, a meta-analysis of 16 studies reported in the British Medical Journal or BMJ revealed.

Doctors whose training on nutrition received from medical school is generally limited if any may advise their patients with bone disease to take calcium supplements with or without supplementation of vitamin D.

But the current study led by  Ian Reid, MD, of the University of Auckland in New Zealand, and colleagues showed patients who had osteoporosis and took calcium supplements were 30 percent more likely to suffer myocardial infarction or heart attack.

The study was based on data from 11 previous clinical trials of 11,921 participants who were followed for a mean period of four years and five observational studies of 8151 participants who were followed for 3.6 years on average.

Patients in none of the studies were using vitamin D along with calcium supplements.

In the current study, separate analyses of data from both types of studies showed similar results, using calcium supplements was associated with 30 percent increased risk of myocardial infarction.

Suzanne Steinbaum, DO, cardiologist at Lenox Hill Hospital in New York City, was quoted by MedPage Today as commenting that "For patients who are at risk for heart disease, with multiple risk factors, or a strong family history, perhaps calcium supplementation should not be considered."

In the analysis of data from studies which were reported by patients, calcium supplementation was linked with an increased risk of myocardial infarction in those who had a dietary calcium intake above an average 805 mg per day, but not in those with a lower dietary intake.

The authors noted that calcium supplements may increase the risk of myocardial infarction by increasing serum calcium levels which have been found linked with higher heart attack risk in some epidemiological studies.

How could calcium supplements increase risk of myocardial infarction?

A myocardial infarction or heart attack occurs when blood flow to an area of the heart muscle is completely blocked, according to the National Heart Lung and Blood Institute.

The blockage results from coronary artery disease - a condition in which plaque builds up inside the coronary arteries. The plaque consists of fat, cholesterol, calcium and other substances in the blood.

Healingdaily.com suggests on its website that it is part of a terrible campaign that convinces patients that cholesterol is the major cause for heart disease and suppresses the fact that calcium plays a potentially even more important role in heart disease.

It should not be news that calcium supplements increase risk of cardiovascular disease such as heart attack as many studies have demonstrated the association.

In fact, a class of drugs called calcium channel blockers have been found at least as effective in reducing risk of cardiovascular disease including heart attack as other anti-hypertensive medications, according to Alcocer L and colleagues from Universidad Nacional Autónoma de México.

The drugs of this class are known to reduce risk of coronary calcification and retard progression of atherosclerosis, Alcocer et al. said in their report published this year in American Journal of Cardiovascular Drugs.

The current study even though there are some limitations suggests that too much calcium can be a risk for myocardial infarction or heart attack.

High concentrations of calcium are found in both animal-based foods such as milk, yogurt and cheddar cheese and plant-based foods such as pinto beans, red beans, white beans, tofu, bok choy, kale, Chinese cabbage, broccoli, rhubarb and spinach.

By David Liu