Milk and health: Wading thru the hype
© 2014 Roy Benaroch, MD
Fiona wrote in: “I’ve seen in the news recently there’s been studies showing concern about milk consumption, especially for adults. They’re linking high milk consumption to health issues later in life. Is this true? Can you write a post on this?”
Food information, like so much else on the internet, has become one-sided and anxiety-provoking. I suppose that’s because people are more likely to click on a link like “Milk is killing you” than “Milk is a nutritious food and a reasonable part of a healthy diet, but you don’t need a ton of it, and there are plenty of other sources of calcium and protein.”
In the latest kerfuffle, we’ve got the dairy peeps versus the anti-milk crowd. On one side, people say milk and other dairy products are a good source of calcium and vitamin D and protein, all of which is essential especially for growing children and people at risk for osteoporosis; on the other side are people claiming that research shows that increased milk drinking will kill you, and doesn’t help keep bones healthy anyway. Who to believe?
Let’s back up a second. Like all mammals, our newborns thrive on a liquid diet made by our mommas called “milk.” The exact composition varies by species—for instance, goat milk has no folate, because goat babies don’t need folate—but overall it’s stuff made of water, nutritive protein, fat, carbohydrates, micronutrients, and immunologically active proteins and cells. In other words, it’s food. It’s really good for newborns and little baby mammals who cannot eat solid food yet. In nature, the amount of time newborn mammals stay on mother’s milk pretty much correlates with how much time they need to grow to the point they can eat the food their mommas eat. Then they wean, and consume bamboo, penguins, green bean casseroles, or whatever else their species typically eats. After weaning, no other animal species continues to consume milk.
Humans are unique animals, because we’ve come to rely on a system of nature-taming developments called “civilization”. Farming, which dramatically increases the food availability per acre, started about 10,000 years ago; dairy milk consumption from non-human animals began maybe 5,000 years later, once goats and proto-cows and sheep were domesticated. Milk had the advantages of being cleaner and less disease-ridden than ordinary water, and also offered good, easily-digestible calories at a time when food could be scarce. Once milk-preservation methods were developed, butter and cheese and yogurt could keep fresh for a much longer time. In many cultures, dairy products became a big part of daily intake.
So, while it’s true that no other adult mammal consumes milk—which is a favorite talking point of the anti-milk crowd—no other adult mammal consumes any farmed food, or any domesticated animals, or any cooked foods, or any omelets. We are not like other animals, and our food sources are entirely unique. Yay us.
While milk and milk products are a historically reasonable thing for humans to eat, their health benefits for mammals old enough to consume ordinary food have been overblown. Yes, they’re a convenient source of calcium and protein and sometimes vitamin D (which, along with vitamin A, is added to cow’s milk—it’s not there naturally.) But these products aren’t the only source of these nutrients. Children who don’t like milk or families who don’t want to consume cow’s milk for other reasons have plenty of other, good, healthful alternatives to get these nutrients.
Recent research has raised valid questions about the wisdom of considering cow’s milk to be an essential part of the diet. A 2014 Swedish study, widely reported in the press, is touted to have shown that higher milk consumption increased overall mortality and did not improve bone health. But the study relied on self-reported food intake dairies, and the study subjects were divided into many cohorts, only some of which showed these effects. And epidemiologic studies like these are fraught with issues of potential reverse causality and uncontrolled confounders. The authors of the study itself went out of their way to list these and other limitations of their study, and explicitly warned people not to change their eating habits until their study could be replicated and better understood; nonetheless, when reported in the press, the study was characterized as having proven that milk will kill you. That’s not what the study showed—that’s what the scaremongers want you to believe.
Milk is fine as a reasonable part of a diet. It’s not essential (at least after weaning), and if you or your children don’t care for milk or would rather eat and drink other things, that’s fine. It certainly shouldn’t be a huge part of any human’s diet after weaning, any more than any other one single foodstuff should account for most of what anyone eats. Want your family to eat healthy? Do these things:
- Eat as a family
- Don’t eat too much.
- Eat a variety of things.
- Slow down and enjoy your food.
- Cook, clean, and shop together.
- Grow vegetables in your garden.
- And stop reading or even clicking on internet scare sites about food!