Older persons, particularly women, are urged by their doctors to increase their daily calcium to 1200 mg per day or more to compensate for the natural loss of bone that occurs as we age. A large study now reveals that calcium supplements are not without risk... big risk.
Areas typically affected by loss of bone as we age.: ©Mayo Foundation for Medical Education & Research
Researchers at the University of Auckland, New Zealand, conducted double blind studies of 12,000 volunteers over 40. Each was assigned to a group which took 500 mg per day of calcium or a placebo. The data was collected on 11 clinical trials after 3.5 years. Subtracting out other risk factors for heart disease, such as high blood pressure, smoking, and previous heart disease, the researchers found that those who took the calcium supplements were 30 percent more likely to have a heart attack than those who took placebos.
There is one bit of relevant information you should know, however. That is that the 500 mg calcium supplements were not accompanied by vitamin D3. Other studies show mixed results on calcium/D3 supplements which is one reason that The University of Auckland researchers will use that combination in an upcoming study.
It might encourage you to know that some research has found that there is not an increased relationship between natural sources of calcium, like milk and yogurt, for example, and risk of heat attack.
Though the 500 mg calcium supplement study did not deal specifically with the mechanisms by which calcium supplements contributed to increased risk of heart attack, other reviews suggest that the supplements increase serum calcium which may effect myocardial infarction (heart attack) directly, or contribute to primary pyperparathyroidism, which can increase the risk of cardiovascular events.
The conclusions by the researchers as well as an editorial writer in the British Journal of Medicine, where the study is published, say that since calcium supplements seem to have at best a 10 percent possibility of enhancing bone density in older persons, the recommendation of these supplements needs to take into consideration the higher risk for heart disease that they pose, especially given the fact that the supplements do not prevent fractures. In medical speak: One needs to re-consider whether these supplements are needed, or that people at risk for bone disease should just be given targeted osteoporosis medications.
Effect of calcium supplements on rish of myocardial infartion and cardiovascular events: meta-analysis. BMJ; Editorial: Calcium supplements in people with osteoporosis, BMJ, via Boston.com