When we were kids, a glass of milk was a symbol of health. In recent years, however, it’s become clear that researchers and clinicians don’t unilaterally agree cow’s milk is actually good for us. Last year, for example, an L.A. Times article weighed in on the debate, pointing out that while there are plenty of facts and findings about milk and its effect on human health has been studied extensively, there are no definitive conclusions as to how much of it we should be drinking. It seems the frothy mustache-maker we grew up with has become a source of dietary confusion and debate.

Conflicting evidence

For kids over the age of one, doctors recommend multiple servings of dairy every day (a serving being a cup of milk or yogurt, or a handful of cubes of cheese) for nutrients like calcium, potassium, and vitamins D and B. Kids could theoretically get all these nutrients from other foods, but a glass of milk covers a lot of bases in one cup.

And little kids also need fat in their diets for proper brain development. But some nutritionists and doctors worry that dairy’s saturated fat may be too much of a good thing. A glass of whole milk contains roughly eight grams of fat and 30 mg of cholesterol. Given the increasing number of overweight kids, the worry is that too much high-fat milk could increase the likelihood of obesity and heart disease later in life. In fact, the American Academy of Pediatrics now recommends that children at risk for being overweight or having high cholesterol drink two percent milk starting at age one (as opposed the former recommendation of whole milk until age two), then switch to one percent a year later. Milk has a lot of calories, and, theoretically, milk-loving kid could also fill up on the drink and forgo other nutrient-rich foods.

Are humans built to drink milk?

Beyond the weight concern, others argue that we aren’t built to drink cow’s milk in the first place. Throughout most of history, human beings were unable to digest the lactose protein in milk beyond early childhood because the enzyme needed to do so naturally stopped working at a certain age. At some point in the last 5,000 years, scientists think a genetic mutation caused some adults to persist in tolerating milk, and that population maintained the trait. Today in the U.S. and parts of Europe, the majority of adults have the necessary enzyme to digest milk, but the world-over, about seventy five percent of people get sick when they drink it.

Given that lactose intolerance is so common and that the main purpose of milk from any animal is to feed infants, it’s probably not intended to be a big part of our diet beyond early childhood. Human breast milk changes in nutritional composition as a child grows – adjusting the amount of fat, for example, depending on the stage of development. Cow’s milk doesn’t do that. It’s a perfect fit for a baby calf, but not necessarily for a growing human being.

It’s confusing, to say the least, since there’s also plenty of evidence that many people are vitamin-D deficient – potentially a major public health problem, leading to higher incidence of cardiovascular disease, cancer, and other chronic conditions. The sun is the best supplier of vitamin D (the rays we avoid to lessen our chance of skin cancer), but fortified milk, along with orange juice and wild-caught oily fish, is our top dietary source.

The milk middle road

The bottom line most doctors see is that milk is a good idea for a toddler if he’s no longer drinking breast milk, and that multiple dairy servings deliver important nutrients for the first years of life. Although we haven’t seen the updated guidelines for kids yet, the new dietary paradigm from the USDA – the healthful “plate” instead of the long-standing food pyramid – gives us some clues about how we might view milk for older children. In the MyPlate diagram, the dairy is in a small glass, with vegetables and fruit making up half the plate, and meat and carbohydrates composing the other half. Dairy has its place, but it’s by no means the center of a meal. Maybe a head of broccoli or a bushel of Swiss chard has replaced milk as being our symbol of health.