Everything is good in moderation, even milk

It is believed that a diet with a high content of dairy products, especially milk, helps to reduce the risk of osteoporosis and related fractures. However, new evidence suggests that drinking large amounts of milk is associated with an increased risk of fractures and an increased likelihood of premature death, both for men and women.

The relationship between the dynamic duo of calcium and vitamin D contained in milk, as well as their important role in maintaining bone health, has long been presented as one of the main components of a full-fledged diet, especially with regard to the development of the child's body.

According to the recommendations of the USDA, daily consumption of 3 cups of dairy products is recommended to maintain good health and improve bone mass. It is also believed that drinking 3-4 glasses of milk a day can reduce the cost of treating osteoporosis by at least 20%.

It is generally believed that milk has a number of other useful properties, including:

• maintaining normal blood pressure;
• reducing the risk of developing cardiovascular diseases and type 2 diabetes;
• preventing the development of colon cancer;
• a source of natural high-quality protein to maintain muscle mass.

The data of an observational study obtained by Swedish scientists working under the guidance of Professor Karl Michaelsson (Karl Michaelsson), question some of the beneficial properties of milk. Especially unexpected were the data indicating the fallacy of the most well-known and hitherto unquestioned relationship between the use of milk and the good condition of bone tissue in old age.

Researchers have suggested that drinking large amounts of milk may actually increase oxidative stress, thereby increasing the risk of premature death and bone fractures.

This hypothesis is based on data according to which milk is the main source of D-galactose. Galactose monosaccharide in combination with glucose forms a molecule of milk sugar disaccharide – lactose.

Experiments on various animal models have shown that chronic exposure to D-galactose is detrimental to health, accelerates the aging process and shortens life expectancy. These consequences are the result of damage to cellular structures caused by oxidative stress, chronic inflammation, neurodegeneration, weakening of immune responses and changes in gene transcription.

To test the hypothesis, scientists analyzed the dependence of mortality and fracture risk on milk consumption in two territorial cohorts:

• the Swedish mammography cohort, consisting of 61,433 women, whose age in the period 1987-1900 was 39-74 years;
• a cohort of 45,339 Swedish men who turned 45-79 in 1997.

When filling out the questionnaire, participants indicated their habits regarding the consumption of 96 common foods and beverages, including milk, fermented milk, yogurt and cheese. When processing the collected information, data on lifestyle, body weight and height, education level and marital status were also taken into account. Data from national registers were used to track the frequency of bone fractures and mortality.

The fate of women from the Swedish mammography cohort has been monitored for 20 years. During this period, 15,541 of them died, and 17,252 had bone fractures (4,259 had hip bone fractures).

Drinking large amounts of milk did not reduce the risk of fractures. Moreover, women who drank 3 or more glasses of milk per day (an average of 680 ml) had a higher risk of mortality than women who drank less than one glass of this drink per day (an average of 60 ml).

In the cohort of Swedish men, 10,112 people died during the 11-year follow–up period, and 5,066 had bone fractures (1,115 had hip bone fractures).

Despite the lower severity of the relationship compared to the female group, the consumption of large amounts of milk increased the risk of premature death in the male group as well.

To identify the alleged relationship of milk consumption with oxidative stress and inflammation, an additional study was conducted. The obtained results confirmed the existence of such a relationship for both sexes. At the same time, the consumption of fermented dairy products, yogurt and cheese demonstrated a negative relationship with oxidative stress and markers of inflammation. The use of these products reduced both the risk of premature death and the risk of fractures, especially in women.

Based on the data obtained, the researchers concluded that drinking large amounts of milk is not accompanied by a reduction in the risk of fractures and, instead, may be associated with an increased risk of premature death for both sexes. It is also possible that there is a relationship between these risks and the content of lactose and galactose in consumed milk, but this assumption has yet to be verified.

The authors warn that, given the observational nature of the study, the results obtained should be interpreted with great caution. They note that such a study can only demonstrate the existence of a correlation, but cannot prove the existence of a causal relationship. Therefore, in order to change the existing recommendations on proper nutrition, it is necessary to confirm the results obtained in further studies.

Article by Karl Michaelsson et al. Milk intake and risk of mortality and fractures in women and men: cohort studies published in the British Medical Journal.

Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru according to Medical News Today:
Milk may increase risk of fractures, overall mortality in both sexes.

31.10.2014