medical ethics

Calcium Supplements: More Heart Attacks, but Also More Osteoporosis

Women in the United States are continually pressured by their doctors and by the media to eat a high-calcium diet and take calcium supplements, supposedly to prevent osteoporosis. I resist this advice, because I’ve known for more than 20 years that osteoporosis is actually most common in the populations with the highest calcium intakes. Now, a study just published in the British Medical Journal warns that calcium supplements could also raise the risk of heart attack, which is the major cause of death in women in the United States.

I found out about the link between high calcium intakes and osteoporosis in the late 1980s, while I was editing a handbook for dietitians. The author wrote that osteoporosis is common only in societies where people eat a lot of dairy products. I was shocked by this information. Later on, I found that both the high protein content and the high calcium content of dairy foods are implicated in causing osteoporosis. For years, Harvard professor Mark Hegsted warned people that osteoporosis was a result of the same kind of diet that causes heart disease. He specifically warned that high calcium intakes probably make osteoporosis worse. Sadly, his warnings fell on deaf ears.

Reading the article in the British Medical Journal made me angry. The study it described was a meta-analysis, which means that it compiled the results of several clinical trials. The researchers found 15 clinical trials in which women were given either calcium or placebo, mostly for the prevention or treatment of osteoporosis. What angered me was the dates of the studies. The earliest one was published in 1989, the latest in 2008. Even by the time the earliest of those studies was done, there was already plenty of reason to believe that calcium supplements would have made the women’s osteoporosis worse, not better. In other words, human research subjects were subjected to unnecessary harm. That sort of thing is a huge violation of medical research ethics. It’s also illegal in civilized countries.

Medical researchers are supposed to do their homework before they start enrolling human beings in a clinical trial. By the time that first study was done, it was already obvious that high calcium intakes make osteoporosis worse, not better. Harvard professor Mark Hegsted explained the problem in an article published in 1986, before the first of the studies included in the meta-analysis.

It’s bad enough that the average doctor has had little to no training in nutrition or dietetics. What’s even worse is that some of the doctors who are doing nutrition studies evidently don’t bother to read the scientific literature on nutrition before they start experimenting on human beings.

According to the article in the British Medical Journal, there were 143 myocardial infarctions in the patients assigned to take calcium and 111 myocardial infarctions in the patients assigned to take a placebo. If these women had been given proper counseling on how to make themselves heart-attack-proof, all of these heart attacks could have been avoided.

Photo by German Tenorio