If recent headlines have made you rethink your use of calcium supplements, Tufts Bess Dawson-Hughes, MD, has some words of wisdom for you: This is absolutely no reason to panic.Dr. Dawson-Hughes, director of Tufts HNRCA Bone Metabolism Laboratory, is referring to a controversial study widely reported as concluding, Calcium Supplements Increase the Risk of Heart Disease in the Elderly. Ian Reid, MD, of the University of Auckland in New Zealand, and colleagues pooled results from 11 randomized controlled trials of calcium supplements totaling 11,921 elderly participants. Among those taking calcium supplements compared to placebo, researchers found a 31% increase in the risk of heart attack, as well as a nonsignificant increase in stroke and mortality risk.The raw numbers were small-143 heart attacks in the calcium groups versus 111 in the placebo groups. But Dr. Reid pointed out that, given the popularity of calcium supplements, the impact could be serious: If you have 1,000 people taking calcium for five years, we will expect to find 14 more heart attacks, 10 more strokes and 13 more deaths in the people given calcium than they would have had if they hadnt been treated with calcium.Supplements affect the body differently than calcium in food, Dr. Reid added: People regard calcium supplements as natural, but they are really not natural at all, he told the Reuters news service. When you take calcium supplements, your blood calcium level goes up over the following four to six hours and goes up to the top end of the normal range. That doesnt happen when you have calcium to eat in your diet because the calcium from food is very slowly absorbed.An accompanying editorial in the journal BMJ proclaimed: Given the uncertain benefits of calcium supplements, any level of risk is unwarranted.Dr. Dawson-Hughes, a leading expert on osteoporosis, doesnt disagree that its better to get your calcium from dietary sources than from pills. But she believes the conclusions in the BMJ study are far too assertive given the evidence. Although the researchers looked at 15 trials and ultimately combined results from 11, she points out, more than half the total data came from a single study. That low-cost study relied entirely on the mails and suffered from poor adherence to the pill-taking regimen. Participants were never asked directly about cardiovascular events. Andrew Shao, PhD, of the Council for Responsible Nutrition, a supplements trade group, is also critical of the study: Seven of the 15 trials evaluated had no, or incomplete, data on cardiovascular outcomes, and only five of the 15 studies accounted for almost all of the cardiovascular outcomes. Further, the researchers chose to exclude any trials administering calcium plus vitamin D-including the Womens Health Initiative, which found calcium plus vitamin D had no effect on the risk of coronary heart disease or stroke.The omission of studies pairing calcium with vitamin D is the clincher for Dr. Dawson-Hughes. Given the crucial role of vitamin D in putting calcium to work for bone health, she says, Theres almost no occasion to recommend taking calcium alone. Indeed, a study published earlier this year in Annals of Internal Medicine (see the June Healthletter) concluded that calcium supplements seem to have minimal cardiovascular effects, but vitamin D supplements at moderate to high doses may reduce cardiovascular disease risk.So what should confused calciumsupplement consumers do now? Concentrate first on getting calcium from dietary sources, Dr. Dawson- Hughes advises. Then adults age 50 and older should use supplements if they have calcium-poor diets and cant fix their diets to bring the total calcium- from food plus supplements-to 1,200 milligrams.Most adult Americans already get 700-800 milligrams of daily calcium from food, so many people need only modest supplementation. The notion that more and more is better and better is ill-founded, Dr. Dawson-Hughes cautions. There is no upside to taking extra calcium beyond 1,200 milligrams, and there are possible downsides-although she doesnt think cardiovascular risks are among those concerns.Everyone age 60 and older should also get at least 800-1,000 IU of vitamin D, she adds. It doesnt need to be in the same pill as the calcium. People at high risk of osteoporosis or with low vitamin D from the skin should get more.TO LEARN MORE:BMJ, dx.doi.org/10.1136/bmj. c3691. International Osteoporosis Foundation www. iofbonehealth.org
