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Study Suggests Milk May Actually Increase The Risk Of Bone Fracture

Alice G. Walton
This article is more than 6 years old.


Recent years have raised some questions about the role of cow's milk in human health. It’s been shown to be linked to heart disease and diabetes, whereas yogurt and other fermented products have been linked to improved heart health. In preventing bone fractures, the research has been more conflicting. “I've looked at fractures during the last 25 years,” lead author Karl Michaelsson told the Washington Post. “I've been puzzled by the question because there has again and again been a tendency of a higher risk of fracture with a higher intake of milk.”

The researchers asked 61,000 women and 45,000 men about their dietary habits, including how often they consumed 96 particular foods, among them, milk, cheese, and yogurt. They followed the women for 20 years and the men for 11 years, noting how many developed hip fractures and other bone fractures, and how many died.

The women not only gained no benefit from drinking more milk, but three or more glasses per day was associated with a significantly greater risk of bone fracture. For men and women both, the more milk they’d consumed, the greater the risk of death.

Cheese and other fermented dairy products did not seem to be linked to the same risk – in fact, as people ate more of these products, their risk of bone fracture declined, as did their risk of mortality.

The authors suggest that milk itself may have a negative effect because it triggers inflammatory processes in the body. Indeed the team found higher levels of markers indicating oxidative stress and inflammation in people who drank more milk.

What is it about milk itself – but not cheese or yogurt – that would lead to inflammation? The culprit may be a sugar that’s present in milk, D-galactose, which has been linked to accelerated aging in the past. “Even a low dose of D-galactose induces changes that resemble natural aging in animals,” the authors write, “including shortened life span caused by oxidative stress damage, chronic inflammation, neurodegeneration, decreased immune response, and gene transcriptional changes.”

There are some caveats here, of course, like the fact that causation wasn’t demonstrated – only correlation. It could be other, as-yet-undiscovered factors that are responsible for the connection. Additionally, reverse causation could be at play, where people who are at higher risk of osteoporosis up their milk intake intentionally. But the authors say this is unlikely, given the time frame used in the study, the fact that cheese and yogurt were linked to reduced risk of bone fractures, and the fact that people without bone fractures still had a higher death risk when they drank more milk.

The study is intriguing, given the frequency with which milk is touted as one of the best tools to keep bones in good health. But it will need a lot of follow-up work before recommendations are changed. In the meantime, yogurt and cheese seem to be on the safe list – and as for milk, as with all things, unfortunately, moderation is probably best.

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