荨麻疹可以脱敏治疗吗:Calcium and Heart Attack Risk: Ending the Con...

Hello. This is Dr. JoAnn Manson, Professor of Medicine at Harvard Medical School and Brigham and Women's Hospital. I would like to talk with you today about the recent report on calcium supplements and heart attack risk,^[1] which continues to alarm and confuse women. I would like to review the findings in light of the recent Institute of Medicine (IOM) report^[2] on recommended intakes of calcium.

The recent IOM report recommends a calcium intake of 1000 mg daily for women in early and middle adulthood until age 50, and 1200 mg daily for women after age 50. On the basis of a comprehensive review of literature, there is no convincing evidence that this amount of calcium, which is important for maintaining bone health, would boost the risk for cardiovascular events in women.

So why did the meta-analysis published recently in the British Medical Journal ^[1] suggest otherwise? Let's take a look. This meta-analysis included 11 separate randomized trials, a total of almost 12,000 women. However, it is important to note that all of the studies that were included were testing supplemental calcium alone without the addition of vitamin D. There are many randomized trials of calcium together with vitamin D that suggest no excess risk for cardiovascular events.

For example, a very large randomized trial, the Women's Health Initiative, which included 36,000 women and tested 1000 mg per day of supplemental elemental calcium together with 400 IU per day of vitamin D, showed a neutral effect for both heart disease and stroke. There was absolutely no evidence of an excess risk for cardiovascular events, or in a subgroup that was tested for coronary artery calcium, no evidence of an increased risk for vascular calcification at this supplemental dose.

Let's take a look at some of the other differences. The study in British Medical Journal did not address dietary calcium sources. There is really no evidence that dietary calcium raises the risk for cardiovascular events. There are several studies, in fact, suggesting that higher intake of nonfat or low-fat dairy products is associated with a lower risk for type 2 diabetes, hypertension, and cardiovascular events. What are some good dietary sources of calcium? Dairy products and fortified juices and cereals as well as kale, collard greens, and other calcium-rich greens are good sources.

We can conclude that the amount of calcium that is recommended for bone health, 1000 mg daily for women until age 50 and 1200 mg daily of calcium after age 50, should not boost the risk for cardiovascular events in women. We don't have to sacrifice bone health to avoid this adverse outcome.

It is important, however, to keep in mind that the IOM does recommend avoiding intakes above 2000 mg of calcium daily for women age 50 and older; this is considered the upper tolerable intake level. Many women will be able to achieve the recommended doses of 1000 mg daily or 1200 mg daily of calcium through dietary sources alone, and the women who need supplements may need only an additional 500 mg per day in supplemental form. Very few women will require more than 1000 mg daily as a supplement.

Thank you very much. This is Dr. JoAnn Manson.

References

1. Bolland MJ, Avenell A, Baron JA, et al. Effect of calcium supplements on risk of myocardial infarction and cardiovascular events: meta-analysis. BMJ. 2010;341:c3691.
2. Institute of Medicine. 2011 Dietary Reference Intakes for Calcium and Vitamin D. Washington, DC: The National Academies Press; 2010. Available at: http://www.iom.edu/Reports/2010/Dietary-Reference-Intakes-for-Calcium-and-Vitamin-D.aspx Accessed January 6, 2011.