Whatever the reason, a decade-long study finds that overweight young people who drink a lot of milk are less likely to develop insulin resistance syndrome, a forerunner of diabetes and a condition that increases the risk of heart attack and stroke.
Among the more than 3,000 people ages 18 to 30 who were followed for 10 years, those who consumed the most dairy products had a 72 percent lower incidence of insulin resistance syndrome than those with the lowest intake, says a report in tomorrow's Journal of the American Medical Association.But that held true only for overweight young adults. In this study, people were defined as being overweight if they had a body mass index (BMI) of 25 or over. (Your BMI is about 25 if you're 5 feet, 9 inches tall and you weigh 170 pounds.) No such advantage was found in leaner people.
Insulin resistance syndrome means high blood pressure, glucose intolerance, and a bad blood lipid profile, high in dangerous triglycerides and low in helpful high-density lipoproteins. Incidence of the syndrome has been rising in the United States for the past three decades.
"I'm aware of published papers from the U. S. Department of Agriculture showing that milk intake over the past three decades has decreased and soda intake has increased," says Mark A. Pereira, an epidemiologist at Boston Children's Hospital and Harvard Medical School, who led the study. "Children who drink more soda drink less milk and have a worse diet, with fewer fruits, grains and whole-grain products."
With some glaring exceptions, milk has good things in it, Pereira says. The sugars it contains are complex, "very different from the sugars in candy. They are converted to blood sugar at a lower rate," he says.
And milk contains a lot of useful protein, he adds, which means that "it is more filling than soda. People who drink milk are less likely to eat too much because it is more filling."
One downside is the fat in whole milk, Pereira acknowledges. That problem can be dodged by observing the American Heart Association dietary rules, which recommend "a couple of servings a day of reduced-fat dairy products," he says.
And the carbohydrate in milk is lactose. Some people have a deficiency of lactase, the enzyme needed to digest lactose. Lactase deficiency occurs in about 15 percent of whites and perhaps 80 percent of blacks and Asians, causing abdominal cramps, bloating, diarrhea and other problems.
With those caveats in mind, Pereira sums up, the study results indicate that "not only milk but all types of dairy products protect against diabetes and heart disease."
"This is just another reason to make sure you include dairy in your diet," says Deanna Rose, a registered dietician in the Philadelphia office of the National Dairy Council. "A while ago there was a report that three servings a day can prevent osteoporosis, more recently that it can reduce high blood pressure. There is a combination of ingredients there that you need for a healthy diet."
Fat? Lactose? Not to worry, says Rose -- just browse through the dairy section of the market.
"There will be something in the dairy case that will be fat-free or lactose-free," she says. "It doesn't matter if it is whole milk, lactose-free milk, or low-fat milk. Lactose intolerance doesn't necessarily mean dairy intolerance. People can include smaller amounts of dairy products. Many tolerate cheeses better than milk. Or there is yogurt. A cup of yogurt has the same amount of calcium as a cup of milk."
If there was a weakness in the study, Pereira says, it is that it was not the gold-standard kind of trial, a randomized study in which some people consistently followed one dietary pattern and others followed another. Instead, it relied on the participants' reports of what they ate.
"We may do a randomized clinical trial sometime," he adds. "It would help us get a handle on cause and effect. Is it the replacement by milk of less helpful foods, or is it the specific effect of some of these nutrients in milk?"
What To Do
If you stick to low-fat products, milk and other dairy foods can be an essential part of a diet to reduce the risk of diabetes and heart disease. An ice cream sundae, for instance, would probably at best cancel itself out.
You can get official information about the kind of diet that is good for you from the American Heart Association. Meanwhile you can read a detailed explanation of the Department of Agriculture's Food Guide Pyramid.
What's your BMI? The Centers for Disease Control and Prevention can calculate it for you.