Coffee is consumed daily around the world, and previous research has associated its consumption with a reduced risk of conditions including type 2 diabetes and cardiovascular disease. Scientists do not yet fully understand the biological processes that could explain those connections. Now, new research from Finland suggests that regular coffee consumption is associated with healthier body composition, favourable metabolic markers and distinct patterns involving sex hormones in men and women.
Researchers from the University of Oulu analysed information from 2,264 people aged 46 who participated in the Northern Finland Birth Cohort of 1966. The team investigated how participants' usual coffee intake was related to circulating metabolites, cardiometabolic risk indicators and sex hormone levels.
People who consumed more coffee tended to have lower levels of both total body fat and visceral fat, along with greater skeletal muscle mass. These differences appeared despite participants with higher and lower coffee consumption having a similar body mass index (BMI). Higher coffee consumption was also associated with lower circulating concentrations of branched-chain amino acids in both men and women. When these biomarkers are chronically elevated, they have previously been associated with insulin resistance and an increased risk of developing type 2 diabetes.
Among men, the clearest differences appeared in hormone patterns. Higher coffee consumption was associated with a more favourable glucose-insulin profile, higher levels of total and bioavailable testosterone, and greater concentrations of sex hormone-binding globulin (SHBG). However, free testosterone and free androgen index were modestly lower. The hormonal associations were less extensive in women. Higher coffee consumption was primarily associated with increased SHBG and lower measures of free androgens.
"Coffee is consumed by millions of people every day, but we still know surprisingly little about how it relates to our metabolism and hormones. What stood out in our findings was a distinct hormonal signature that did not disappear even after we accounted for BMI and lifestyle factors, with several of these associations differing between men and women," said Luca Verroest, lead author of the study and doctoral researcher at the University of Oulu.
The findings raise the possibility that hormonal pathways could help explain the previously observed relationship between coffee consumption and metabolic health. However, because the research was observational, it cannot establish that drinking coffee directly caused any of the biological differences identified in the study.
The context also makes the research especially relevant. Finland is among the world's countries with the highest coffee consumption, with an average annual consumption of approximately 11.8 kilogrammes (26 pounds) per person.
The researchers noted that the results offer a starting point for studies designed to determine whether coffee itself produces these biological changes and, if so, what compounds could be responsible. Scientists are currently investigating these questions using animal models, with the long-term aim of advancing towards intervention studies in humans.
Additional research will be necessary before the findings can be used to shape dietary recommendations. The study, "Associations of habitual coffee intake with testosterone and cardiometabolic markers: the Northern Finland Birth Cohort 1966 study", was published in the European Journal of Nutrition.