Several studies have linked coffee drinking to a reduced risk of conditions such as type 2 diabetes and cardiovascular disease, but the biological mechanisms underlying these benefits remain unclear.
In a new Finnish study, conducted by the University of Oulu on 2,264 participants from the "Northern Finland 1966 Birth Cohort," all aged 46, the results revealed some interesting answers.
Researchers have found that regular coffee consumption is associated with a healthier body composition, through lower total and visceral fat and higher skeletal muscle mass, despite similar body mass indexes among participants.
Higher consumption has also been linked to lower levels of branched-chain amino acids, which are biomarkers associated with insulin resistance and an increased risk of type 2 diabetes when chronically elevated.
What is most striking is the clear difference in hormonal effects between the sexes, with the associations being stronger in men, as coffee was associated with improved ability of the body to regulate blood sugar and insulin, higher total and bioavailable testosterone, and increased sex hormone-binding globulin, with a slight decrease in free testosterone and free androgen index.
In women, the effect was limited and represented by an increase in sex hormone-binding globulin and a decrease in free androgens, indicating a distinctive hormonal signature that was not affected by body mass index or lifestyle factors, according to lead author Luca Verwest.
However, the researchers acknowledge that these results, published in the European Journal of Nutrition, are observational correlations and not cause-and-effect relationships, meaning they cannot definitively say that coffee causes these biological changes, especially since the study was conducted in Finland, one of the world's highest coffee-consuming countries with an annual average of 11.8 kilograms per person.
However, the results provide a solid basis for future studies, currently being conducted on animal models, with the aim of moving to human trials to understand the compounds responsible for these effects, before they can inform dietary recommendations.
