Is it any wonder that people have become skeptical about medical advice? For decades Americans, especially women, were told to swallow calcium supplements. The extra calcium was supposed to build strong bones.
Then last July an article was published in a British medical journal (BMJ, online July 29, 2010) that turned this advice upside down. Researchers analyzed data from 11 studies involving more than 12,000 people. Those who received calcium supplements were about 30 percent more likely to have a heart attack than those given placebo pills.
As you might expect, this created considerable controversy. Doctors were reluctant to believe that a simple supplement they had been recommending for years might cause harm to patients. Some criticized the findings on the grounds that the analysis did not include vitamin D. Many asserted that if patients had been taking both vitamin D and calcium, the outcome would have been different.
Now a new study has just been published in BMJ (online, April 19, 2011) that confirms a connection between calcium supplements and cardiovascular complications. The scientists analyzed data from more than 16,000 women over the age of 40 who participated in the Women’s Health Initiative and were not taking calcium or vitamin D supplements before the study began. When these volunteers were randomized to take calcium plus vitamin D, their risk of heart attack and other vascular problems increased about 20 percent.
In addition, the review analyzed results from 13 other studies of calcium and vitamin D supplements. The additional data confirmed the results: study subjects taking the supplements were about 24 percent more likely to have a heart attack or other cardiovascular event than those taking placebo.
The authors conclude that these results, together with the results of other clinical trials of calcium supplements, should prompt a reassessment of the use of calcium supplements.
Although this study addresses the main objections to the previous analysis, not everyone is happy about it. Some physicians are still reluctant to consider that calcium supplements might be risky. Others are no doubt as confused as their patients about what a woman should do if she wants to prevent osteoporosis without risking heart disease.
Perhaps everyone would feel less conflicted if it turned out that supplementary calcium were not necessary for osteoporosis prevention. That is exactly the argument of a well-documented book, Building Bone Vitality, by Amy Joy Lanou, PhD, and Michael Castleman. The authors present data demonstrating that calcium is not a magic bullet for bone strength and that vegetables and fruits are essential.
Anyone interested in this approach can learn more from our one-hour radio interview on Bone Vitality (show # 752) with Michael Castleman and Walter Willett, MD, DrPH. Dr. Willett is Chair of Nutrition at Harvard’s School of Public Health.
The reversal on calcium supplementation will be hard for many to accept. Nevertheless, there is now evidence showing us that calcium supplements are neither as safe nor as effective as we had once imagined.
