A friend started a new diet, and he said he was surprised to learn milk and other dairy products can actually cause, not prevent, osteoporosis. Can you explain?
This notion pops up from time to time, but rest assured that there’s broad consensus among nutrition researchers and registered dietitians that getting enough calcium, along with vitamin D, is an important part of a healthful diet, and dairy products remain a good source of these critical nutrients.
But the factors affecting calcium absorption and how the body uses calcium are complicated, and researchers are still discovering information about it. So, be prepared to continue to hear occasional back-and-forth about the best guidance.
One of the studies often cited by those who warn people off dairy products is from 1997. This Harvard University study examined data from more than 77,000 women who self-reported their food intake in questionnaires in 1980, 1984, and 1986. Surprisingly, they found that higher reported consumption of milk and other dairy didn’t protect women against hip or bone fractures.
However, other examinations of the evidence on dairy foods and bone health indicate that the 1997 study doesn’t tell the whole story.
For example, a 2000 comprehensive review of research conducted on dairy foods and bone health between 1985 and 1999, including the above study, was published in the American Journal of Clinical Nutrition. It determined that 42 percent of the studies’ findings showed favorable effects of dairy foods on bone health, while 53 percent showed insignificant effects and only 5 percent showed unfavorable effects.
One of the issues regarding dairy foods and calcium is related to dairy’s protein content. When a person eats more protein, more calcium is lost through the urine. So, wouldn’t it make sense to get calcium from foods without protein?
Unfortunately, it’s not that simple. There are many things that affect how the body handles calcium. While dairy might have some issues, so do other foods.
Even the “Nutrition Source” from Harvard’s School of Public Health, whose researchers conducted the 1997 study, doesn’t advocate abstaining from dairy products. Just read its article “Calcium and Milk: What’s Best for Your Bones and Health?” online at www.hsph.harvard.edu/nutritionsource/calcium-full-story/. You’ll see that the authors suggest that while American adults “may not need as much calcium as is currently recommended” (which is 1,000-1,200 milligrams a day), they still recommend one daily serving of milk in addition to another 300 milligrams of calcium from other sources.
While deliberation about calcium and dairy foods is sure to continue, you can rely on this piece of guidance: Eat a balanced diet with a wide variety of nutritious foods, limited in added sugars and saturated fat, and with plenty of produce and whole grains, while maintaining a healthful weight and getting enough physical activity. If you do that, everything else should fall into place.
Chow Line is a service of the College of Food, Agricultural, and Environmental Sciences at The Ohio State University and its outreach and research arms, Ohio State University Extension and the Ohio Agricultural Research and Development Center. Send questions to Chow Line, c/o Martha Filipic, 2021 Coffey Road, Columbus, OH 43210-1043, or firstname.lastname@example.org.