Postmenopausal women have long been told that in order to prevent fractures and protect against osteoporosis, they should include plenty of calcium in their diets. Because women often find it difficult to obtain all of the recommended calcium from their food intake alone, however, many rely on supplements to make up the difference. However, a new study, published in the journal Heart, warns that taking calcium supplements may actually increase one s risk of heart attack.
For the study, researchers from the University of Zurich followed about 24,000 men and women for 11 years and found that, compared to participants who took no calcium supplements, those who did had an 86 percent greater risk of having a heart attack. Interestingly, however, dietary calcium intake was actually associated with a reduced heart attack risk.
Needless to say, the implications of the study results are not yet clear and it s important to note that there were relatively few heart attacks in the study overall. Indeed, Dr. Taylor Wallace, senior director of scientific and regulatory affairs for the Council for Responsible Nutrition (part of the dietary supplement industry), doesn t think the study is consistent with the total body of science. As he points out, postmenopausal women are especially vulnerable to a low intake of calcium; and for those who are unable to get enough calcium from food, they should absolutely be taking a calcium supplement or they are at risk of developing osteoporosis or a fracture.
ACSH advisor Dr. Judy Stern, professor of clinical nutrition and internal medicine at the University of California-Davis, agrees that it s not realistic to assume that women will obtain the necessary levels of calcium from diet alone. That would require that women drink the equivalent of four glasses of milk a day, she says, which is unlikely and can lead to additional problems, like an increased risk of becoming overweight or obese. The calories from four glasses of milk can range from 400 to 800 daily, which is very high; that s why calcium supplements are a practical solution all around.
I find this study confusing, adds ACSH s Dr. Ruth Kava. The increased risk in those who took the supplements didn t seem to be dose-related; I would wait for additional work to be done before recommending that women stop using calcium supplements.