Drinking a lot of milk is not accompanied by a lower risk of fracture and instead may be associated with a higher rate of death, according to research published in the British journal BMJ.
This may be explained by the high levels of lactose and galactose (types of sugar) in milk which have been shown to increase oxidative stress and chronic inflammation in animal studies, say the researchers.
However, they point out that their study can only show an association and cannot prove cause and effect.
They say the results “should be interpreted cautiously” and further studies are needed before any firm conclusions or dietary recommendations can be made.
A diet rich in milk products is promoted to reduce the likelihood of bone fractures but previous research looking at the importance of milk for the prevention of fractures and the influence on mortality rates show conflicting results.
So a research team in Sweden, led by Professor Karl Michaëlsson, set out to examine whether high milk intake may increase oxidative stress which in turn affects the risk of mortality and fracture.
Two large groups of 61,433 women (aged 39-74 years in 1987-1990) and 45,339 men (aged 45-79 years in 1997) in Sweden completed food frequency questionnaires for 96 common foods including milk, yoghurt and cheese.
Women were tracked for an average of 20 years, during which time 15,541 died and 17,252 had a fracture, of whom 4,259 had a hip fracture.
In women, no reduction in fracture risk with higher milk consumption was observed. Women who drank more than three glasses of milk a day (average 680 ml) had a higher risk of death than women who drank less than one glass of milk a day (average 60 ml).
Men were tracked for an average of 11 years, during which time 10,112 died and 5,066 had a fracture, with 1,166 hip fracture cases.
Men also had a higher risk of death with higher milk consumption, although this was less pronounced than in women.
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