How do you decide?
On the one hand, the National Dairy Council and the recent USDA’s MyPlate hawk the benefits of milk, and there is a body of research available to back some of their claims.
On the other hand, the Harvard School of Public Health’s new Healthy Eating Plate recommends cutting back on milk products—and there is some research supporting this view for specific sectors of the population.
If a dietitian can’t sort through the morass of differing research available about milk and dairy products, what is the public to think?
On the positive side
Dairy products or milk have been associated with a decrease in the risk of colon cancer and may have some benefit in helping people who are on weight loss diets. In a multi-center trial by Zemel and colleagues, participants who consumed 3 servings of dairy products a day doubled the increase in fat loss.
Milk products have also been found to have a positive effect on blood pressure. The DASH diet (Dietary Approaches to Stop Hypertension) includes a recommendation to have between two and three servings of non-fat dairy products per day.
On the negative side
There is some preliminary research that higher intakes of milk may be linked through its lactose content to ovarian cancer. And, in one large study, men who drank seemingly moderate amounts (2 cups or more per day) of milk were found to have an elevated risk of advanced prostate cancer.
Much of the negative research cited above comes from cohort-type studies, where participants are asked about their intake of certain foods or nutrients and then followed over a number of years to chart the appearance rate of disease. These studies show associations between nutrients and disease but cannot show causality.
So what do we know?
It has been fairly well established that calcium is needed for bone and teeth mineralization. Without it comes osteoporosis, which is a weakening of the bones, often leading to falls and hip fractures.
Milk and yogurt supply the greatest amount of calcium per single serving in the diet. In addition, for many Americans, it is the only consistently reliable source of calcium.
There are other sources of calcium—including certain green leafy vegetables, such as collard greens, bok choy, broccoli, collards, kale, mustard greens, and turnip greens. These supply adequate amounts of calcium to meet the Recommend Daily Requirement, if eaten in sufficient quantities on a regular basis.
Nuts and canned fish, such as salmon eaten with bones, are also reliable sources—again if eaten in sufficient quantities.
These are all good choices and as a dietitian, I certainly encourage my patients and clients to include more of these foods in their diet.
But from a practical standpoint, most Americans don’t eat any collards, kale, mustard or turnip greens or bok choy. Although many Americans do eat broccoli, they don’t eat enough of it. And the migration to eating more of these foods is likely to occur over the course of many years not months.
Milk, in its 1% or skim versions supplies calcium, high quality protein, and the only significant source of vitamin D in the diet. It also has only 12 grams of carbohydrate per serving.
If you like milk, including 2 servings a day and using legumes, leafy greens and nuts for the rest of your calcium (and vitamin and mineral needs) is a reasonable way to hedge your bets, until we in the health community have a definitive idea of what is really going on.
And if dairy is simply not your thing, you may need to consider supplements, if you are not eating sufficient selections of non-dairy sources.
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