Food is one of the favorite subjects of lovers of dialectical combat, perhaps because it is not easy to determine who is right. Coffee is, after water, the most consumed liquid in the world, and there is intense discussion around this drink. This week, an international team of researchers led by Susanna Larsson, from the Karolinska Institutet, in Stockholm (Sweden), publishes in the journal BMJ Medicine a study that can be used by anyone who wants to drink coffee, not only with a clear conscience, but even with a certain sense of moral superiority.
Larsson and his colleagues concluded that high levels of caffeine in the blood can reduce a person’s amount of body fat and their risk of type 2 diabetes, which is associated with aging and certain lifestyle habits. The results are consistent with many observational studies that, going back decades, have observed a relationship between coffee consumption and a lower risk of diabetes. In an article published in 2018 by the same Larsson, it was estimated that each cup of coffee with caffeine ingested per day reduced the risk of developing diabetes by 7%, a benefit that, with 6%, was almost equal to that of coffee . decaffeinated. Another study carried out by scientists from the World Health Organization (WHO) in 2017 calculated that three coffees a day reduce premature mortality by between 8 and 18%.
Despite the accumulation of positive results, these observational studies do not guarantee that the detected links are causal. In 1991, the WHO placed coffee on the list of possible carcinogens and, years later, reversed the decision when it found that the higher incidence of cancer among coffee growers could be explained by other associated habits, such as the cigarette that sometimes accompanies coffee . what a drink. The authors of this article point out that randomized trials, which are very expensive and complex to carry out, with which causality can be established, have not been carried out to analyze the effect of caffeine on the development of diabetes or cardiovascular disease.
Genetic variants of coffee
To at least partially overcome these limitations, the scientists used a new method known as Mendelian randomization, which uses genetic variations with a known function to assess the causal effect of a risk factor. In this case, they looked at the CYP1A2 and AHR genes, which determine how fast our bodies process caffeine, in 10,000 people. Individuals with genetic variants that cause caffeine to stay in the blood longer tend to drink less coffee because they experience longer stimulation but have higher concentrations of caffeine in their blood plasma.
The observed effect is not large enough individually to consider drinking coffee to prevent diabetes.
Gemma Rojo, Malaga Regional University Hospital
With this approach, which tries to separate the effect of caffeine in the blood on obesity or diabetes from other factors related to coffee consumption, they observed that people with genetic variants that delay the processing of caffeine and favor its greater presence in the blood had a lower index body mass and lower percentage of fat. The main reason for the reduction in the risk of diabetes, which is attributed to 43% of the effect, is weight loss, caused by its ability to accelerate metabolism and reduce appetite, among other qualities.
Gemma Rojo, researcher at the Hospital Regional Universitario de Málaga, considers the study interesting, but recalls “that the effect observed individually is not so great as to consider drinking coffee to prevent diabetes, and that for a person who already has diabetes , It will not help you to control it, because it will not lower your blood sugar levels. well observed at a population level and is not very useful for individual decision-making,” rivet.
The authors of the study published today by the journal BMJ medicine They believe that, given their results, it would be interesting “to conduct randomized studies to see whether caffeinated and calorie-free beverages may play a role in reducing the risk of obesity and type 2 diabetes.” Jorge Ferrer, head of the Genomic Regulation and Diabetes group at the CRG in Barcelona, thinks that this approach is excessive “given that this study did not take into account other variables such as mental well-being or how caffeine affects quality of the dream.” However, he finds this type of Mendelian randomization study useful for obtaining very hard-to-obtain information about caffeine, “following many people for several years, giving some caffeine and others a placebo” and controlling many others. variables.
As with most things to do with food, a positive effect of caffeine on energy intake is not a silver bullet for losing weight or preventing chronic diseases like diabetes. Eating less and better and exercising more are still the most effective solutions.
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