Dairy: The Good & The Bad
(BlackDoctor.org) — For reliable dietary advice, most nutritionists agree, look to the food pyramid. But when it comes to advice about milk and dairy, the question is: Which pyramid?
The official food pyramid comes from the U.S. Department of Agriculture. It incorporates the recommendations of top ranking nutrition scientists from around the country. But other groups, disagreeing with some aspects of the USDA’s recommendations, have constructed alternative pyramids. One of the most influential is the food pyramid created by researchers at the Harvard School of Public Health. And one of the big differences between its advice and the USDA’s relates to milk and dairy products.
In 2005, the USDA’s dietary guidelines increased the recommended servings of milk from two to three cups a day. The latest guidelines, released in 2010, repeat that advice. They specifically urge Americans to get more fat-free or low-fat milk and related dairy products.
According to Harvard’s food pyramid, on the other hand, milk isn’t an essential part of a healthy diet — and may pose risks.
Dairy: The Good
The USDA’s recommendations are based on the fact that milk is a prime source for three important nutrients: calcium, potassium, and vitamin D (which is added to fortified milk.)
“Milk contains a big package of nutrients that are especially important to bone health,” says Connie M. Weaver, PhD, who directs the nutrition department at Purdue University. “People who don’t drink milk tend to be deficient in them. So it makes good sense to encourage people to consume dairy products.”
Milk is also a good source of potassium — another compelling reason the USDA committee increased the recommended servings from two to three in 2005, according to Penny Kris-Etherton, PhD, RD, professor of nutrition at Pennsylvania State University, who served on the committee.
Too much sodium and too little potassium together are risk factors for high blood pressure. Unfortunately, most Americans get too much salt and don’t get enough potassium. Milk isn’t the only source, to be sure. Many vegetables and fruits are also rich in potassium. But according to Kris-Etherton, experts hesitated to increase the recommended servings of vegetables, which were already more than most Americans were eating.
“Short of encouraging people to eat more vegetables, we thought the best way to ensure adequate potassium was to recommend low-fat milk,” she tells WebMD.
Dairy: The Bad
Not everyone thinks that was a good idea. Indeed, experts at the Harvard School of Public Health have labeled the milk recommendations a “step in the wrong direction.” One the most prominent critics is Walter Willett, MD, PhD, professor of epidemiology and head of the nutrition department at the Harvard School of Public Health.
“One of the main arguments for USDA recommendations is that drinking milk or equivalent dairy products will reduce the risk of fractures. But in fact there’s very little evidence that milk consumption is associated with reduced fractures,” Willett says.
Indeed, countries in which almost no milk is consumed, such as many Asian countries, have low rates of fractures, he points out.
It’s true, he acknowledged, that milk is a good source of potassium. But the levels used for the USDA recommendations are much higher than they need to be to prevent hypertension, according to Willett. “We’re much better off advising people to consume less salt,” he says.
As beverages go, milk is relatively high in calories. One cup of 2% milk has 138 calories, for instance. Drinking three cups a day adds 366 calories to the diet — a lot for anyone watching their weight.
But Willett’s chief worry is that drinking too much milk may pose dangers. “By now there’s quite a body of data showing a higher risk of fatal prostate cancer associated with milk,” he tells WebMD. “And though the evidence is somewhat mixed, we’ve still seen a slightly higher risk of ovarian cancer associated with drinking three or more servings of milk.”
Dairy: What We Can All Agree On
When it comes to practical advice, fortunately, the two sides aren’t all that far apart. Consuming a cup or two of milk or equivalent dairy is fine, according to Willett. “The point isn’t that you have to give up dairy,” he says. “But it’s also important for people to know that they don’t have to drink milk to be healthy.”
People who are lactose intolerant, including nearly 60 percent of African Americans, can’t easily drink milk or consume certain other dairy products. For them, and for people who don’t choose to drink milk, it is important to favor other sources of calcium. Examples include lactose-free dairy, and leafy green vegetables such as collards, spinach and bok choy, beans, and calcium-fortified orange juice or soy milk, and vegetables.
It’s also wise to make sure you’re getting adequate potassium, which is abundant in tomatoes, spinach, sweet potatoes, bananas, oranges, and other fruits and vegetables.