Fitness Investigates: Behind Milk Myths
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Fitness Investigates: Behind Milk Myths

Are dairy products good for you -- or not? Can milk, cheese, and yogurt help you lose weight and fight disease? Fitness investigates.

Can Milk Help You Lose Weight?

To brie or not to brie? That's what you might be asking yourself in light of the recent headlines about dairy products: For every potential benefit, like weight loss, there seems to be a possible risk, like ovarian cancer. Experts say this may stem from the fact that dairy products are made from milk, which is surprisingly complicated stuff. "Milk contains calcium, fat, lactose, vitamin D and, in some cases, hormones; some of these components are thought to reduce disease risk and others to increase it," explains Marji McCullough, senior epidemiologist with the American Cancer Society in Atlanta.

Ultimately, how much you lighten your latte depends on your medical history. Women with certain health concerns might want to incorporate more dairy in their diet. And those with other health worries might get their daily 1,000 milligrams of calcium (crucial to preventing osteoporosis) from supplements and other non-dairy foods like canned salmon, tofu, and calcium-fortified orange juice. Here's what you may have heard -- and what you need to know.

Headline: Dairy Helps You Lose Weight

In 2004, Michael Zemel, PhD, a professor of nutrition at the University of Tennessee, authored a much-publicized study in the American Journal of Clinical Nutrition that found that consuming three servings of low-fat dairy products daily (one yogurt, a glass of skim milk, and one and a half ounces of cheese) helps burn fat and speed weight loss. A 2005 Dutch study reported that people who consumed adequate amounts of calcium were slightly leaner than their calcium-poor counterparts.

Expert Take: According to Zemel, the weight-loss benefit can't be replicated by taking a calcium supplement. He suspects that the slimming effect comes from an interaction between the calcium and other components in dairy products. But don't dive headfirst into a pot of fondue just yet. "You can't include milk, cheese, and yogurt in your diet, eat whatever you want, and not gain weight. You still have to pay attention to calories."

What to Do: If you want to drop pounds, include three servings of low-fat dairy products in your daily diet, but also keep an eye on overall calorie and fat count.

Can Milk Cause Acne?

Headline: Milk Can Give You Acne

A study in the Journal of the American Academy of Dermatology analyzed responses from more than 47,000 women in Harvard's national Nurses' Health Study II. Those who said they drank more than three servings of milk per day during their teens were 22 percent more likely to have had severe acne than those who drank one (or fewer) servings per week. Those who had two or more glasses of skim milk daily were 44 percent more likely to have had severe acne as teenagers.

Expert Take: If you tend to break out, dairy may exacerbate it, but if you're not prone to acne, milk products are unlikely to cause it. "Whether you develop acne depends on your genes and environmental factors," says Boston-based dermatologist Ranella Hirsch, MD. Several components in milk may exacerbate an outbreak; the most significant is hormones.

What to Do: If you're worried about exacerbating breakouts, consider getting your calcium from other sources, and/or drink organic milk, which doesn't contain added hormones.

Can Dairy Affect Breast Cancer Risks?

Headline: Dairy Products May Lower Your Breast Cancer Risk

A 2005 American Cancer Society study found that women who consumed two or more servings of dairy products daily (including low-fat yogurt, cheese, and skim milk) had up to a 20 percent lower risk of postmenopausal breast cancer compared with women who ate the least dairy. Low-fat products offer the most protection.

Expert Take: The theory is that calcium or vitamin D lowers breast cancer risk. Supplements appear to have no effect.

What to Do: Even if you're worried about breast cancer, keep your daily consumption to two or three servings of low-fat dairy. "More research needs to be done before we make general recommendations," says McCullough.

Is Milk Connected with Ovarian Cancer?

Headline: Milk May Raise Your Chances of Ovarian Cancer

A study in the International Journal of Cancer reported that women who drank one or more servings of skim or low-fat milk daily had a 32 percent higher risk of any ovarian cancer compared with those who had three or fewer servings monthly. The frequent milk drinkers also had a 69 percent higher risk of the most serious type of malignant ovarian tumors.

Expert Take: The lactose in milk may contribute to the risk.

What to Do: If you're concerned about a heightened risk of ovarian cancer (if, for example, you've got a family history of the disease), you can get your calcium from a supplement, but make sure it also contains vitamin D.

Does Dairy Prevent Diabetes?

Headline: Drinking Low-Fat Milk May Help Prevent Diabetes

Researchers at Massachusetts General Hospital analyzed data from 41,254 male participants and found that dairy consumption, particularly low-fat dairy, was associated with a decreased risk of developing type 2 diabetes.

Expert Take: Milk consumption has indeed been linked to a lower incidence of diabetes, says Robert Rizza, MD, a professor of medicine at Mayo Clinic College of Medicine in Rochester, Minnesota, and president of the American Diabetes Association. But he notes that it's hard to draw concrete conclusions from studies like this because they're epidemiological, meaning that scientists examine the habits of a large group of people and spot noteworthy associations but can't isolate exactly which behaviors contributed to the preventative effect. "It's hard to remove the effects of a single food from an overall pattern of eating," explains Dr. Rizza. "People who eat low-fat dairy products tend to have healthier diets in general," he says.

What to Do: The animal fat in whole-milk products can raise disease risk, so be sure to stick to skim milk and low-fat dairy products.

Can Milk Affect Cardiovascular Health?

Headline: Milk Every Day Keeps Cardiovascular Disease Away

A recent study of Japanese men and women found that calcium intake from dairy products was associated with a reduced risk of stroke. Another 2005 study published in the Journal of Epidemiology and Community Health showed that men who drank the most milk each day had a lower risk of heart disease or stroke than those who drank the least milk.

Expert Take: The Japanese study participants filled out questionnaires that detailed their overall eating habits. So again, it's hard to tell whether the calcium alone reduced disease risk. And despite the fact that whole milk also protects against heart disease, saturated fat (in whole milk) does raise LDL levels and heart attack risk, says Alice Lichtenstein, a professor of nutrition science and policy at Tufts University.

What to Do: Keep on eating low-fat dairy products.

Originally published in Fitness magazine, May 2006.