More caffeine, less risk of diabetes and body fat, says a Swedish research study published in the British Medical Journal

A research study links higher levels of caffeine in the blood with a lower risk of diabetes and body fat. Researchers believe that this should be further studied, although other experts doubt its usefulness in making individual decisions.

An international team of researchers led by Susanna Larsson from the Karolinska Institutet in Stockholm, Sweden, have published a research study in the BMJ which shows how high levels of caffeine in the blood can reduce a person’s body fat and the risk of type 2 diabetes, which is associated with aging and certain lifestyle habits.

The results are consistent with those of many observational studies dating back decades, which have seen a relationship between coffee consumption and a lower risk of diabetes. In an article published in 2018 by Larsson herself, it was estimated that for every cup of caffeinated coffee consumed per day, the risk of developing diabetes was reduced by 7%, a benefit that, at 6%, was almost equal to that of decaffeinated coffee. Another piece of research conducted by scientists from the World Health Organization (WHO) in 2017 found that three cups of coffee per day reduce premature mortality by between 8 and 18%.

Despite the positive results, these observational studies do not allow us to guarantee that the links detected are causal. In 1991, the WHO included coffee in the list of possible carcinogens, and years later, reversed the decision when it was discovered that the higher incidence of cancer among coffee growers could be explained by other associated habits, such as smoking, which sometimes accompanies the consumption of coffee. The authors of this research point out that no randomized studies, which are very expensive and complex to carry out, have been conducted to establish the link of randomness and analyse the effect of caffeine on the development of diabetes or cardiovascular diseases.

To overcome these issues at least in part, scientists have used a new method, known as Mendelian randomization, which uses genetic variations with a known function to assess the randomness effect of a risk factor. In this case, they analysed the CYP1A2 and AHR genes, which determine the speed at which our body processes caffeine, in 10,000 people. Individuals with genetic variants that cause caffeine to remain in the blood longer tend to drink less coffee because they feel a longer stimulant effect, but they have higher concentrations of caffeine in their plasma.

With this approach, which seeks 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 slow down caffeine processing and favour its greater presence in the blood had a lower body mass index and a lower percentage of fat. The main reason for the reduced risk of diabetes, which accounts for 43% of the effect, is weight loss, caused by caffeine’s ability to speed up metabolism and reduce appetite.