A diet rich in dairy products, particularly milk, is promoted to reduce the likelihood of osteoporotic fractures. However, a new study published in the BMJ suggests that a high intake of milk is associated with a higher risk fractures and a higher rate of death in men and women.

Share on Pinterest A study claims that an intake of three or more glasses of milk a day could perhaps do more harm than good.

Milk contains 18 out of 22 essential nutrients. The relationship between the dynamic duo of calcium and vitamin D in milk and their importance in maintaining bone health has long been promoted in nutritional education, especially in terms of child development.

The United States Department of Agriculture (USDA) recommend a daily dose of 3 cups of dairy to support good health and improve bone mass. An intake of three or four glasses of milk a day has been suggested to save at least 20% of health care costs related to osteoporosis.

Milk is also presented to have many other benefits, including:

Maintaining healthy blood pressure

Reducing the risk of cardiovascular disease and type 2 diabetes

Protection from colorectal cancer

Providing natural, high-quality protein for muscle mass.

Observational research conducted in Sweden, led by Prof. Karl Michaëlsson, disputes some of the health benefits of milk, in particular providing conflicting data for the most cited connection between milk and prolonged bone health.

The researchers hypothesized that a high consumption of milk may, in fact, increase oxidative stress, leading to an effect on the risk of mortality and bone fracture.

The hypothesis is based on the indication that milk provides the main dietary source of D-galactose. Galactose makes up half of lactose, the sugar found in milk.

Experimental evidence in various animal species indicates that a chronic exposure to D-galactose is detrimental to health, a source of aging and shortened lifespan. These consequences are due to oxidative stress damage, chronic inflammation, neurodegeneration, decreased immune response and gene transcriptional changes.

To test the hypothesis, the investigators used two community-based cohorts to analyze the association of milk consumption and mortality and fracture rates:

The Swedish Mammography Cohort: a group of 61,433 women, aged 39-74 in 1987-1990

The Cohort of Swedish Men: a group of 45,339 men, aged 45-79 in 1997.

In answer to a questionnaire, the participants reported their average consumption of up to 96 common foods and beverages, including milk, fermented milk, yogurt and cheese. Lifestyle information, weight and height were gathered and factors relating to education level and marital status were also taken into account. National registers were utilized to track fracture and mortality rates.