Milk: Superfood or Poison?

Fat-fighting powerhouse—or hormone-disrupting sludge?

The Tyrolean Iceman, found frozen in the Italian Alps, lived 5,300 years ago. But scientists recently uncovered evidence in his genome of a familiar modern condition: lactose intolerance.
No problem for him—his buddies hadn’t yet domesticated animals.
Since then, not only have we tamed cows and filled our dairy cases with their milk, we’ve also accumulated a confusing and often contradictory body of research about dairy—and an anti-dairy camp almost as outspoken as dairy lovers.

“Organic versus milk from cows treated with recombinant bovine growth hormone, super health food versus poison—take your pick. It’s hard to know where to start counting the issues people have with dairy,” says Marion Nestle, Ph.D., M.P.H., a professor of nutrition, food studies, and public health at New York University and one of the most widely respected nutritionists in the industry. “Emotions run high because milk is primal—it’s everyone’s first food.” It also boasts an efficient public relations team funded by industry groups, she notes.

Truthfully, there are some people who absolutely shouldn’t have dairy: About 2.5 percent of modern Americans have a potentially life-threatening milk allergy. Nearly one in 10, like the Iceman, are missing the enzyme needed to digest milk and may need to take a lactase pill before drinking it.
But is milk good for the rest of us? We sifted through piles of studies and interviewed leading experts on both sides—and in the middle—to sort out the controversy.

The Claim: Milk can help you lose weight

True, there’s some evidence that people who regularly consume dairy are slimmer, but some studies have also found no connection.

Experimental trials of milk as a diet aid have murkier results. A randomized controlled trial published last year in Nutrition & Metabolism found differences in fat and calories alone, not calcium and dairy, changed dieters’ body composition.

A 2008 study found participants who were told to cut calories, exercise, and drink milk as part of a community-based weight-loss program shed more pounds if they drank more milk. However, the study didn’t track calorie intake. These results may mimic the way dairy works in the real world. There’s probably no magical fat-melting ingredient in milk, but like any other nutritious food, you’ll lose weight if drinking it helps you cut calories, Nestle says. And it might: Protein has satiating effects, and a glass or small carton is relatively portion-controlled, says Katherine Zeratsky, R.D., L.D., of the Mayo Clinic in Rochester, Minnesota.

The Claim: Milk can help you build muscle

A growing body of research has boosted chocolate milk’s rep as the ideal postworkout recovery drink. Most recently, cyclists who chugged the stuff after a tough hour-and-a-half ride recovered more quickly than those who downed a carb-only sports drink, judged by muscle biopsies and their speed on the next ride.
Though most of the research on milk and recovery has been funded by the dairy industry, you shouldn’t throw it out automatically.

Most experts now agree that protein repairs damaged muscles after a hard workout. Milk is rich in whey protein, one of the best for building muscle because the essential amino acids it contains match up neatly to our physiological needs, says Dan Benardot, Ph.D., R.D., a professor of nutrition and researcher at Georgia State University and author of Advanced Sports Nutrition. It’s certainly not the only food or drink that could refuel you, but chocolate milk has a convenient blend of nutrients that rehydrates you, restores sodium and potassium, and gives you sugar to replace the glycogen your muscles burned during hard cardio or weight-lifting workouts, he says.

The Claim: Milk causes cancer

In the documentary Forks Over Knives, nutrition researcher T. Colin Campbell explains experiments linking casein in milk to tumor growth in rats, which are frequently used to study human cancers. But the evidence that similar effects occur in humans isn’t compelling, Nestle says.

Some large-scale population studies back a link between milk and the risk of prostate cancer. For example, a 2010 paper found Canadian men had double the risk of prostate cancer if they consumed more dairy products, especially milk.

But to focus in on this study is like looking at “Guernica” through a toilet paper tube: Milk is associated with a decreased risk of colorectal and bladder cancer. Research is thin on the links between dairy and other malignancies.

Plus, these links don’t show that milk causes cancer. Dairy foods are one small part of a pattern of eating and other lifestyle habits that influence cancer risk. There are just too many other variables, Zeratsky says.

The Claim: Organic milk is healthier than conventional

Cows at organic dairies aren’t treated with antibiotics, the overuse of which can lead to treatment-resistant superbugs. They also don’t receive recombinant bovine growth hormone (rBGH). But does this difference affect the milk?

Under a program overseen by both the FDA and state regulatory agencies, the dairy industry tests every truckload of milk for antibiotic residue and removes offending batches from the food supply.
Even if you were to drink milk tainted with rBGH, digestive enzymes destroy it.

However, concerns remain regarding whether cows treated with rGBH produce milk with higher levels of insulin-like growth factor, a substance linked to cancer in humans. Nestle, for one, sticks to organic milk. Research hasn’t proven hormones or pesticides used in conventional farming are harmful, she says, but she’d prefer to avoid them.

The bottom line: Milk isn’t essential—but it can do your body good

Many cultures don’t eat dairy and have thrived, Nestle says. And with planning, vegans can have healthy diets. “I don’t know that milk can stand at the top of the pedestal and be the superfood,” says Zeratsky. Claims that it can do everything from boost brainpower to prevent gout—all made in the past few years—may be oversimplified or exaggerated. Many of them have been based on observational studies that don’t prove cause and effect.

“But I think milk offers many nutritional benefits that for many people improve the overall quality of their diet,” Zeratsky continues. Milk seems to offer the biggest bang for your buck, both in calories and dollars, according to a 2011 study in the Journal of the American College of Nutrition. While only about 10 percent of the average American’s calories come from dairy, milk products are one of the top—and cheapest—sources of key nutrients such as calcium, vitamin D, phosphorus, and vitamin B12.

“Milk is a very important food in that it can deliver a lot of nutrients with relatively few calories,” Benardot concludes—and dairy offers many options, from yogurt to cheese to gelato. “But in the end, milk products should be consumed as part of an otherwise varied diet to have the most beneficial nutritional impact.” After all, no single food is likely to fulfill all your dietary needs any more than the Iceman is likely to wake up and ask for a Klondike bar.