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