Full-fat, low-fat or skim? Used to be, there weren't many choices to make over what to pour on your cereal. But the number of alternatives to cow's milk -- soy, goat's, hemp milk, more -- has steadily grown.
Each has its fans: those who swear by goat's milk's creamy texture or who love almond milk's subtle, nutty flavor. But when it comes to nutrition, there's no clear winner.
Cow's milk is a good source of protein but can be high in saturated fats. Hemp milk offers little protein but is rich in certain essential fatty acids. For some, an allergy is the main concern when choosing milk. For others, digestibility drives the decision. "There are dozens of differences in all of these milks," says Alexandra Kazaks, professor of nutrition at Bastyr University in Kenmore, Wash.
Here's a look at the nutritional pros and cons of standards and newcomers in the dairy case. See Page E3
Whole cow's milk packs 150 calories per cup, and about half of those calories come from fat. (See the related chart for a nutritional breakdown of all these different milks.) The 8 grams of fat in a cup of whole milk includes 5 grams of saturated fat, which can raise blood cholesterol. The American Heart Assn. recommends limiting saturated fat intake to 7% or less of daily calories: An adult consuming 1,800 calories per day would get more than one-third of that in an 8-ounce glass of whole milk.
Skim and reduced-fat milks provide the same amount of protein without the high levels of saturated fats or the cholesterol whole milk also contains. They also retain all of the calcium found in whole milk -- up to 300 milligrams, about one-third of the recommended daily intake. According to the Institute of Medicine, adults require between 1,000 and 1,300 milligrams of calcium a day for optimum bone strength. And cow's milk has long been promoted by nutritionists and dietitians as a good source of this important mineral, as well as the vitamin D needed to absorb the mineral.
But "there's a fair amount of controversy in that whole area," says Larry Kushi, associate director for epidemiology in the division of research at Kaiser Permanente Northern California in Oakland. The issue is just how important calcium -- and milk as a source of calcium -- truly is for bone health.
Scientists increasingly began to question the relationship after several studies, including two unusually large ones, failed to find evidence linking increased milk consumption to a decreased risk of fractures, a sign of bone health.
A 12-year study of more than 77,000 women, conducted by Harvard researchers and published in 1997, found that women who drank two glasses of milk a day had roughly the same risk of hip or forearm fractures as women who drank one glass or less per week. A 2003 investigation of the same population found that although vitamin D intake reduced the risk of hip fractures in post-menopausal women, high calcium and milk intake did not.
The science on the relationship between cow's milk and cancer is also somewhat murky, and researchers are working to clarify this. Population studies have produced good evidence that increased dairy consumption, including that of milk, may decrease the risk of colorectal cancer. But studies also suggest that the risk of prostate cancer may increase with increasing milk consumption.
The evidence for female cancers -- including breast, ovarian and endometrial cancers -- is more mixed. Studies conducted several decades ago were less likely to demonstrate a link between dairy consumption and female cancers than more recent ones, and some nutrition experts think this difference may be linked to industrial practices that have increased the levels of the hormone estrogen in cow's milk.
Then there's the issue of milk allergy, an immune-system reaction to any of the several types of casein, whey or other proteins in milk. About 2.5% of children develop cow's milk allergies in their first year, according to the National Institutes of Health, and 80% outgrow it in adulthood.
Other individuals suffer from lactose intolerance, the inability to digest the dominant sugar found in milk. The intolerance (which causes gas, bloating and diarrhea) stems from a lack of lactase, the enzyme required to break down the milk sugar lactose. It is far more common than milk allergy. "Most of the world's population can't digest milk," says Dr. Scott Sicherer, professor of pediatrics at the Jaffe Food Allergy Institute at Mount Sinai School of Medicine in New York, and co-author of the 2009 book "The Complete Idiot's Guide to Dairy-Free Eating." "Our bodies are not made to drink this stuff."
The popularity in the U.S. of cow's milk makes us a bit of an anomaly: Globally, goat's milk is a far more popular drink.