Most people grow up thinking that milk is good for their body, but a new study casts doubt on the purported benefits of dairy milk.
The new research, which was published in the journal BMJ on Oct. 28, suggests that milk offers no benefit in preventing bone fractures. Worse, drinking more milk may possibly even lead to earlier death.
Researcher Karl Michaelsson from the Uppsala University in Sweden and his colleagues asked over 61,000 women who were between 39 to 74 years old as well as more than 45,000 men 45 to 79 years old to fill out questionnaires on how often they consume dairy products such as yogurt, cheese and milk.
After monitoring the female participants for 20 years and the male participants for 11 years from the time the subjects answered the questionnaires, the researchers did not find evidence that consuming more milk is correlated with reduced risks for bone fractures.
In fact, women who drank no fewer than three glasses of milk a day had 16 percent increased odds of experiencing bone fracture and 60 percent more odds of breaking their hip compared with the women who drank less than one glass of milk a day.
The researchers also observed that the women who consumed more milk had 90 percent increased risks of dying from cardiovascular disease and 44 percent increased risks of dying from cancer during the study period. In men, those who drank at least three glasses of milk daily had 10 percent increased odds of dying earlier.
"High milk intake was associated with higher mortality in one cohort of women and in another cohort of men, and with higher fracture incidence in women," the researchers wrote.
The results, however, were reversed when it comes to consumption of fermented dairy products such as yogurt. Michaelsson said that the difference could be attributed to the lactose and galactose, sugars present in milk, which were shown to accelerate aging processes in animal studies.
Although the study was conducted over a long period of time and involved a considerable number of participants, the researchers are not yet ready to come up with cause and effect conclusions. They also want to look at alcohol consumption and weight to see if those had an influence on the results.
"Michaelsson and colleagues raise a fascinating possibility about the potential harms of milk with an interesting inner mechanism involving D-galactose," Mary Schooling from the City University of New York wrote in an accompanying editorial. "Their findings should be interpreted cautiously, though, because the authors rely on observational, not experimental evidence, potentially reflecting correlation not causation."