A study assures that a glass and a half of milk a day is associated with a higher heart risk

The work, led by Karl Michaëlsson from Uppsala University (Sweden), shows that the risk of cardiovascular disease increases as the amount of milk consumed increases, but this effect is only observed in women, not in men.

Furthermore, the study clarifies that the consumption of fermented dairy products, such as yogurt or kefir, is not associated with this risk.

However, another study in 2020 published in ‘The Lancet’ indicated that drinking milk, or consuming dairy products, at least three servings a day, can be beneficial for cardiovascular health. According to a study of more than 130,000 people in 21 countries, dairy products are associated with lower rates of cardiovascular disease and mortality. Additionally, the report saw that people who consumed three servings of dairy per day had lower rates of mortality and cardiovascular disease compared to those who consumed less than 0.5 servings of dairy per day. (A standard serving of dairy was equivalent to a glass of milk at 244 g, a cup of yogurt at 244 g, a slice of cheese at 15 g, or a teaspoon of butter at 5 g).

The work now published in the journal ‘BMC Medicine’ is based on more than 30 years of monitoring of the eating habits of 100,775 adults in Sweden.

The researchers analyzed the participants’ dairy consumption in detail, taking into account risk factors related to heart disease such as the level of physical activity, smoking, and the presence of previous illnesses. The results reveal that women who consumed 300 ml of milk or more per day (more than a glass and a half) had a higher risk of developing coronary heart disease.

This increased risk was greater as the amount of milk ingested increased: for example, women who consumed 400 ml of milk per day had a 5% higher risk of cardiovascular problems compared to those who drank only 100 ml. This risk was up to 21% higher when consumption reached 800 ml per day.

Why only women?

The study was especially striking because the increased risk of heart disease was not detected in men.

According to experts, this phenomenon could be related to hormonal factors or differences in how men and women metabolize the nutrients in milk.

The results do not appear to be linked to the amount of saturated fat in the milk, as the risk remained even when consumption of whole, semi-skimmed, or skimmed milk was analyzed separately. Furthermore, the same negative effects were not observed in the consumption of fermented dairy products such as yogurt or kefir, which are also an important source of beneficial nutrients, such as calcium and protein.

However, Professor Esther López-García of the Autonomous University of Madrid warns that although this study provides new data, it is important not to lose sight of global dietary recommendations. In Spain, the Spanish Agency for Food Safety and Nutrition suggests a moderate consumption of up to three dairy products a day, especially if you opt for fermented versions for people with lactose intolerance.

For his part, Matthias Schulze, an expert in Molecular Epidemiology at the German Institute of Human Nutrition, points out to Science Media Center that the strengths of the study, such as the large sample size and long-term follow-up, but also comments on the importance to consider other confounding factors that could influence the results, such as educational level or the proportion of smokers among participants with high dairy consumption.

In conclusion, although this study suggests that high milk consumption could increase the risk of heart disease in women, it is important to remember that the overall dietary context, lifestyle habits and genetic factors play a crucial role in cardiovascular health.

Therefore, moderation in dairy consumption, along with a balanced diet, remains the most prudent recommendation for the majority of the population, the researchers say.