Some experts say it's a health hazard. Others say it's the most nutritious food you can find. We investigate all the claims about milk to find out if you should have a glass

“Milk is a deadly poison," according to the Dairy Education Board. In fact, if you peruse this special interest group's Web site, notmilk.com, you'll find dozens of articles about the purported evils of this popular beverage. One claim, for example, is that milk from cows contains cancer-causing hormones and dairy industry dollars have kept that fact bottled up. All of which may leave you second-guessing your next sip.

However, as a nutritionist, I've found that most men thrive on milk, whether their goal is to lose fat or build muscle. So to be sure it's safe, I've investigated all the anti-milk claims, sifting through the research while also turning a critical eye to pro-milk propaganda. After all, the only agenda I have is my clients' health. The result: all your milk questions, answered.

Is milk really a fat-burning food?

Maybe. In a 6-month study, University of Tennessee researchers found that overweight people who downed three servings a day of calcium-rich dairy lost more belly fat than those who followed a similar diet minus two or more of the dairy servings. In addition, the researchers discovered that calcium supplements didn't work as well as milk. Why? They believe that while calcium may increase the rate at which your body burns fat, other active compounds in dairy (such as milk proteins) provide an additional fat-burning effect. Of course, the key to success is following a weight-loss diet to begin with. After all, downing your dairy with a box of doughnuts is no way to torch your gut.

Does it build muscle?

Absolutely. In fact, milk is one of the best muscle foods on the planet. You see, the protein in milk is about 80 percent whey and 20 percent casein. Both are high-quality proteins, but whey is known as a "fast protein" because it's quickly broken down into amino acids and absorbed into the bloodstream. That makes it a very good protein to consume after your workout. Casein, on the other hand, is digested more slowly. So it's ideal for providing your body with a steady supply of smaller amounts of protein for a longer period of time--like between meals or while you sleep. Since milk provides both, one big glass gives your body an ideal combination of muscle-building proteins.

Cows are given hormones. Doesn't that make their milk unhealthy?

Not unless you're injecting the milk. Here's the full story: In 1993 the FDA approved the use of recombinant bovine growth hormone (rBGH) in cattle. This practice resulted in greater milk production at less cost to the dairy farmer, a savings that has been passed on to you at your local supermarket. But it has also sparked much controversy, because rBGH boosts milk's concentration of insulin-like growth factor (IGF), a hormone that's been linked to cancer.

Unlike steroid hormones, which can be taken orally, rBGH and IGF must be injected to have any effect. That's because the process of digestion destroys these "protein" hormones. So drinking milk from hormone-treated cows doesn't transfer the active form of these chemicals to your body. However, there is one ethical downside to consider: It's not good for the cows. Canadian researchers discovered that cows given hormones are more likely to contract an udder infection called mastitis.