Milk bad for bones & lowers longevity, but not fermented foods

Posted on Thu, 30 Oct 14

A fascinating new study has found that regularly drinking milk is associated with increased oxidative stress, inflammation, more bone fractures and a shorter life span. But the reverse was true for fermented dairy products.

A large-scale study of over 100,000 Swedish men and women found that over a 20-year period those who drank three or more glasses of milk a day had elevations in markers of oxidative stress (urine 8-iso-PGF2α) and inflammation (serum interleukin 6) and significantly increased risk for premature death (1). And women also had a higher risk of fractures, including hip fractures.

Consumption of cheese or fermented milk products was associated with lower mortality and fracture rates in women, and there were some modest risk reductions in men.

Contrary to popular recommendations to increase dairy consumption the proposed benefits of milk for bone health are not clear and have long been controversial, so this discovery is not completely surprising (2).

The investigators theorise that D-galactose, present at high levels in milk but not fermented products, may help explain their observations. Studies of D-galactose in experimental models and animals suggest it can increase oxidative stress and inflammation and accelerate ageing and chronic disease development they point out.

In an accompanying editorial Professor C Mary Schooling said these new findings "raise a fascinating possibility," and that more research is needed to confirm the associations (3). "As milk consumption may rise globally with economic development and increasing consumption of animal source foods, the role of milk in mortality needs to be established definitively now," she wrote.

References:

1. Michaëlsson K, Wolk A, Langenskiöld S, Basu S, Warensjö Lemming E, Melhus H, Byberg L. Milk intake and risk of mortality and fractures in women and men: cohort studies. BMJ. 2014 Oct 28;349:g6015. - link to free-full text
2. Bischoff-Ferrari HA, Dawson-Hughes B, et al. Milk intake and risk of hip fracture in men and women: a meta-analysis of prospective cohort studies. J Bone Miner Res. 2011 Apr;26(4):833-9. - link to abstract
3. Schooling, CM. Milk and mortality. BMJ 2014;349:g6205 - link to free full-text