Six studies containing almost 200,000 women could find no association between drinking milk and lower rates of fractures.
Almost no one will dispute that when a baby is born, breast milk is the best nutrition a mother can provide. All mammals nurse their young, and breast milk benefits a newborn infant in ways above and beyond nutrition. In fact, until 1 to 2 years of age, the American Academy of Pediatrics, the World Health Organization, the Institute of Medicine and more promote breast-feeding as optimal.
More and more evidence is surfacing, however, that milk consumption may not only be unhelpful, it might also be detrimental.
More than 10,000 years ago, when human beings began to domesticate animals, no adults or older children consumed milk. Many people don’t drink it today because they are lactose intolerant. They do just fine.
But if you believe the advertising of the dairy industry, and the recommendations of many scientific bodies, they are missing out on some fantastic benefits to milk consumption: that milk is good for bones, contains calcium and vitamin D, and “does a body good.”
There’s not a lot of evidence for these types of claims. In 2011, The Journal of Bone and Mineral Research published a meta-analysis examining if milk might protect against hip fracture in middle-aged and older adults. Six studies containing almost 200,000 women could find no association between drinking milk and lower rates of fractures.
More recent research confirms these findings. A study published in JAMA Pediatrics this year followed almost 100,000 men and women for more than two decades. Subjects were asked to report on how much milk they had consumed as teenagers, and then they were followed to see if that was associated with a reduced chance of hip fractures later in life. It wasn’t.
A just-released study in The BMJ that followed more than 45,000 men and 61,000 women in Sweden, age 39 and older, had similar results. Milk consumption as adults was associated with no protection for men, and an increased risk of fractures in women. It was also associated with an increased risk of death in both sexes.
This wasn’t a randomised controlled trial, and no one should assume causality here. But there’s no association with benefits, and a significant association with harms.
Even studies that examine the nutrients in milk, trying to look for protective effects, often come up short. A 2007 meta-analysis in the American Journal of Clinical Nutrition examined high-quality studies of how calcium intake was related to fractures. The many studies of more than 200,000 people, age 34 to 79, could find no link between total calcium intake and the risk of bone fractures.
It is true that vitamin D is necessary for calcium absorption, and for bone health, but that doesn’t mean that most people need to consume more. A meta-analysis published this year in The Lancet examined the effect of vitamin D supplementation on bone mineral density in middle-aged and older adults. It found that, for the most part, consuming extra vitamin D did not improve the bones of the spine, hip or forearm. It did result in a statistically significant, but less clinically meaningful, increase in bone density at the top of the thighbone.
In addition, milk is not a low-calorie beverage. Even if people drink nonfat milk, three cups a day can mean an additional 250 calories consumed. Low-fat or whole milk has even more calories. In an era when every other caloric beverage is being marginalized because of obesity concerns, it’s odd that milk continues to get a pass.
Yes, it’s full of protein. Most Americans aren’t protein deficient, though. Even people who avoid animal milk are worried they’re missing something. Rather than acknowledge that they get along just fine without it, many seek out “milk” substitutes, like soy milk, around which whole industries have been built.
– Aaron E Caroll