Drinking milk may not protect our bones from fractures - and could even
increase a person's risk of dying from heart disease, according to a major new
study in Sweden.
In surprising results, an investigation into dietary habits of more than
100,000 people found those who drank more milk were no less likely to break a
bone. Among women, higher milk consumption was actually linked to an increased
risk of hip fractures.
Even more strikingly, people who drank more than three glasses of milk - around
680ml - per day, were more likely to die over the course of the study, which
tracked 60,000 women for 20 years, and 45,000 men for 11 years.
The effect was most pronounced among women, who were nearly twice as likely to
die, with heart disease the condition with the strongest links to higher milk
Although potentially alarming, the authors of the study from Uppsala University
urged caution and said their evidence was not strong enough for dietary
recommendations to change.
Women who took part in the study were aged 39-74, and the men 45-79 when the
research began, so it is not surprising that significant numbers died over the
following two decades. The study was observational, matching people's
self-reported answers to dietary surveys with their medical records, and does
not prove cause and effect.
Although the researchers took several confounding factors such as smoking rates,
alcohol use and weight into account, commentators said their influence may have
However, experts from several countries agreed that the results merited further
"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," said Professor Mary Schooling, of
City University of New York's school of public health.
The study is published in the British Medical Journal.
Current dietary guidelines recommend milk and other dairy products as good
sources of protein and calcium, which is essential for healthy bones. There is
no suggestion in the study that drinking one glass of milk a day is unhealthy.
The researchers did not make a distinction between full fat, semi-skimmed or
Intriguingly, other dairy products including yoghurt and cheese were linked with
better bone health and lower mortality risk.
The authors have suggested that the cause of milk's adverse effect may be
galactose, a type of sugar, high levels of which are present in non-fermented
milk but not in fermented products. Galactose has been shown to have harmful
effects such as inflammation and chemical imbalances in animal studies, but
evidence of their role in human health is scant.
Gaynor Bussell, a dietician and public health nutritionist said that the study
was interesting but warned that food questionnaires were "not the gold standard"
for understanding daily intake.
"We do know that increase in inflammation is associated with reduced bone
density and so the effect of galactose certainly needs to be looked at in
further studies," she said.
"Calcium is required in the diet for bone health and we require approximately
the daily amount of calcium that's in about a pint of milk. So milk is a very
convenient source of calcium as well as many other vitamins and minerals. Some
caution is required here in interpreting the results and so I would urge some
more research in this area that can back or refute these findings. One such
study is insufficient to base public health decisions on."