 “The tide started to turn in 2005 when results from two British studies showed that calcium didn’t prevent fractures—even when taken in combination with vitamin D. The next year, results from a large American trial, the Women’s Health Initiative, showed that postmenopausal women who took a calcium–vitamin D combination were no less likely to break a hip than women who took a placebo pill, although the density of their hip bones increased slightly. In 2007, a Swiss and American team, including some researchers from Harvard, reported the results of a meta-analysis of over a dozen studies of calcium. They found no connection between high calcium intake, from either food or pills, and lower hip fracture risk. In fact, when they limited their analysis to four randomized clinical trials with separate results for hip fractures, they found that extra calcium increased the risk.”
Bottom line: we don’t need anywhere near as much calcium as the U.S. government and the dairy industry have been recommending. High intake may even be harmful. If it adheres honestly to the overwhelming weight of scientific evidence, the federal government will revise downward its recommendations on calcium and dairy products in the coming years.
Best Sources of Calcium
Walter Willett, PhD, chair of the Harvard School of Public Health’s nutrition department, widely recognized as one of the world’s leading experts on the role of nutrition in health promotion and disease prevention, is quoted in the same issue of HEALTHBeat referring to “real drawbacks to overdoing calcium, especially if dairy foods are the source,” specifically noting “studies linking high consumption of dairy products to ovarian and prostate cancer … particularly strong for metastatic and fatal prostate cancer.”
If dairy products bring risks as well as possible benefits, what other sources of calcium are available? The answer is greens and beans. Greens, of course, are where dairy cows get their calcium. And while we humans can’t digest grass, we do a very good job at digesting nutritious green leafy vegetables like kale, collards, and chard (spinach is nutritious, but its calcium isn’t readily accessible), as well as broccoli, almonds, soy, and all sorts of beans. As always, the key is to find recipes for these foods that you truly enjoy.
What Does Build Strong Bones?
At this point, you may be wondering, “If a high intake of calcium is not the key to building strong bones, what is?” The answer is two-fold: weight-bearing exercise and Vitamin D (from sunshine or supplements). An excellent summary of the scientific research on this subject, focused primarily on building healthy bones in youth, appeared in 2005 in Pediatrics.3 (We plan to explore Vitamin D in greater detail in a future issue, but if you need more information now, this article from the American Journal of Clinical Nutrition is dependable and wide-ranging).
The take-home message of the Pediatrics article is that encouraging children and adolescents to enjoy active play outdoors (exercise plus sunshine vitamin D) is more important than having them drink milk or consume other dairy products, as long as they get enough calcium from other sources. Remember, it’s possible to do too much of a good thing, so we should take care not to let our kids (or ourselves) overdo sun exposure at peak hours of the day. For adults and children alike, exercise (including the weight-bearing kind) is crucial. And for people of all ages, a balanced whole foods diet is essential to well-being.
Daniel Redwood, DC, is Editor-in-Chief of Health Insights Today.
REFERENCES
- Hegsted DM. Calcium and osteoporosis. J Nutr. 1986;116(11):2316-2319.
- Bischoff-Ferrari HA, Dawson-Hughes B, Baron JA, et al. Calcium intake and hip fracture risk in men and women: a meta-analysis of prospective cohort studies and randomized controlled trials. Am J Clin Nutr. Dec 2007;86(6):1780-1790.
- Lanou AJ, Berkow SE, Barnard ND. Calcium, dairy products, and bone health in children and young adults: a reevaluation of the evidence. Pediatrics. Mar 2005;115(3):736-743.
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