The Great Milk Debate: 9 Common Questions

Does milk help prevent osteoporosis? Or cause it, as some milk opponents claim?

Some anti-milk groups claim that dairy products actually increase the risk of osteoporosis, the severe loss of bone mass that often accompanies aging. They point to the fact that in most parts of China and India, where dairy products are rarely consumed and calcium comes primarily from green vegetables, the rate of osteoporosis and fractures is much lower than in the U.S., where dairy consumption is high. But it's not possible to blame these national differences in bone health solely on dairy intake, since genetic, cultural, and life-style factors, as well as other dietary ones, undoubtedly also come into play. It is highly unlikely that drinking milk causes osteoporosis.

One possible problem with dairy products is that they are rich in protein--and a very high protein intake slightly increases calcium excretion in urine and might reduce bone density. However, adequate protein helps keep bones strong, and the high levels of calcium in dairy products may more than offset the small adverse effect their protein may have on bones. In addition, milk is almost always fortified with vitamin D, which may be at least as important as calcium for bone health, according to recent research.

Bone loss is caused by many factors besides diet. According to noted calcium researcher Dr. Robert Heaney, of Creighton University in Omaha, the great majority of studies show that calcium from dairy products has a protective effect on bones. Getting calcium from milk may provide longer-lasting benefits than getting it from supplements. Milk contains other nutrients important for bones besides calcium and vitamin D, such as magnesium, phosphorus, and potassium. In the grand scheme of factors affecting bone health, dairy and calcium intake after early adulthood probably plays only a small beneficial role. But don't believe claims that dairy products harm your bones.

What about milk and heart disease?

If you consume lots of whole milk, whole-milk yogurt, and cheese, you may see your blood cholesterol levels rise, especially if these foods contribute to weight gain. But you can get dairy products in nonfat or low-fat versions, which are lower in calories. There is evidence that increased intake of milk is linked with a reduced risk of stroke and heart attack. Certain substances in milk may even help lower cholesterol. As noted earlier, nonfat or low-fat dairy products are an important part of the DASH diet and can thus help lower high blood pressure.

Is milk the cause of acne in adolescents?

For many years, teens and their parents have blamed diet for outbreaks of acne--chocolate being the prime suspect. But most experts do not think that specific foods play a role. Still, some dermatologists disagree, and some blame milk. The theory is that the hormones in milk interact with human hormones and cause pimples. In 2008 in the Journal of the American Academy of Dermatology, Harvard researchers presented preliminary evidence that drinking skim milk was associated with acne in young boys. There was no explanation for why only skim milk, not whole milk, would have this effect.

Can milk help you lose weight?

Some studies have suggested that milk (or its calcium) can help people lose weight or at least prevent weight gain. A few years ago the dairy industry trumpeted this possibility in ads, but the USDA told it to stop. Even the positive studies, mostly funded by the industry, showed only very small benefits over long periods.

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