Ask the doctor: Why should I limit my dairy intake to one to two servings a day?
Q. In the January issue, you recommended the Harvard Healthy Eating Plate, which includes only one to two servings of dairy a day. Don't we need more than that to get enough calcium?
A. Experts at the Harvard School of Public Health (along with colleagues at Harvard Health Publications, which publishes Harvard Women's Health Watch) created the Healthy Eating Plate to suggest some deficiencies in the U.S. Department of Agriculture's MyPlate, which was released in June 2011 (replacing the familiar food pyramids). Both plates are meant to integrate the latest nutrition advice and serve as at-a-glance aids to planning healthy meals. (To see the plates, go to www.health.harvard.edu/womenextra.) For example, both convey the important message that fruits and vegetables should make up half your plate at every meal. But the Healthy Eating Plate also directs users to the healthiest choices within each major food group; for example, we recommend eating "whole grains" and "healthy protein" rather than simply "grains" and "protein," as MyPlate does. These distinctions are important. Refined grains like white bread and white rice contain less fiber and less nutrients than whole grains, and "protein" could include processed meats, which are not considered healthy.
The Healthy Eating Plate also recommends less dairy than MyPlate—one to two servings a day of milk or the equivalent rather than milk at every meal. One to two servings is enough to satisfy much of our requirement for calcium, and the rest can be obtained from sources such as dark green leafy vegetables and beans (calcium is more highly absorbed from these foods than from milk), tofu, and fortified orange juice and cereals. For example, 500 to 600 mg per day could come from two dairy servings and the rest from these other foods. Dairy can be high in fat and a source of extra calories (even when low-fat milk is used), and if we rely on it to supply most or all of our calcium, we displace healthy plant foods that, unlike dairy, are high in fiber and antioxidants. Dark green leafy vegetables, in particular, are a good source of vitamin K, which is important in bone formation.