(RxWiki News) Past research and advertising campaigns suggested that milk made bones stronger and improved overall health. But new research suggests that may not be true.
Drinking milk is not tied to a reduced risk for bone fracture or death, the authors of a new study found. In fact, high milk intake might increase those risks.
Despite these findings, the study authors said more research on the topic is needed before health officials can make any concrete dietary recommendations about milk intake.
"Our results may question the validity of recommendations to consume high amounts of milk to prevent fragility fractures," the Swedish research team, led by Karl Michaelsson, MD, of Uppsala University, wrote. "The results should, however, be interpreted cautiously given the observational design of our study."
By "observational design," the authors are referring to the fact that the results were based on surveys of patients — the researchers had no control over what the patients did or did not do and had to depend on patient-reported data. They surveyed more than 107,000 Swedes — 61,433 women and 45,339 men — who ranged in age from 39 to 79 years old. The patients answered questions about their intake of common foods like milk, yogurt and cheese, among many others.
The study authors followed up with the female patients for about 20 years on average. During that time, 15,541 died and 17,252 sustained a bone fracture.
Women who drank a lot of milk were no less likely than those who drank no milk to have a fracture. And, the authors found, women who drank more than three glasses of milk per day were nearly twice as likely to die during the study period than those who drank one glass or less.
Results among the men were similar. Of the 45,339 men, 10,112 died during the roughly 11-year study period, and 5,066 had a fracture. The data showed that milk didn't have a protective effect against fractures in men. Also, men who had a higher milk intake had a higher death risk, but not quite as high as that of the women.
The authors noted that patients who drank a lot of milk were more likely to have oxidative stress and inflammation — both linked to cancer and other disease risk. The authors hypothesized that lactose and galactose — sugars found in milk — could cause the stress and inflammation, and that could lead diseases that raise death risk.
Also, the study authors said participants who ate fermented milk products like yogurt and cheese did not appear to have a raised risk for death — those who ate a lot of these foods actually had a lowered risk for both fracture and death.
The author of an editorial about this study said it's always good to take a closer look at claims made about foods — even those widely considered healthy, such as milk.
"As milk features in many dietary guidelines and both hip fractures and cardiovascular disease are relatively common among older people, improving the evidence base for dietary recommendations could have substantial benefits for everyone," wrote C. Mary Schooling, PhD, of the City University of New York School of Public Health in New York City.
The study authors emphasized the need for further research on the health effects of milk consumption.
The study and editorial were published Oct. 28 in the BMJ.
The Swedish Research Council funded the study. The authors disclosed no conflicts of interest.