People all over the world drink coffee every day. Earlier studies showed that coffee drinkers often have a lower risk of diabetes and heart disease. Scientists still do not know exactly why. New research from Finland gives more clues.
Researchers at the University of Oulu looked at 2,264 adults who were 46 years old. They were part of a long‑term Finnish health study. The scientists asked how much coffee each person usually drank and then measured blood chemicals, heart‑related risk markers, and hormone levels.
Coffee Drinkers Had Less Fat and More Muscle
People who drank more coffee tended to have less total body fat and less belly (visceral) fat. At the same time, they had more skeletal muscle. These differences showed up even though their body‑mass index (BMI) was similar to people who drank less coffee.
Higher coffee intake was also linked to lower levels of branched‑chain amino acids in the blood. When these molecules stay high for a long time, they are tied to insulin resistance and a higher chance of getting type‑2 diabetes.
Different Hormone Patterns in Men and Women
Among men, drinking more coffee was connected to a healthier sugar‑insulin balance. Men also had higher total and bioavailable testosterone and more sex‑hormone‑binding globulin (SHBG). Their free testosterone and free androgen index were a little lower.
Women showed fewer hormone changes. The main link was higher SHBG and lower free androgen levels.
Hormones Might Explain Coffee’s Health Links
The study suggests that hormones could be part of the reason coffee is linked to better metabolic health. Because the research only observed people, it cannot prove that coffee directly causes these changes.
Finland is one of the world’s biggest coffee consumers, with people drinking about 11.8 kg (26 lb) each year.
Scientists say the results are a starting point. Future experiments will test whether coffee itself creates these changes and which coffee compounds are responsible. Animal studies are already under way, and human trials may follow.
More research is needed before doctors can give official diet advice based on these findings.
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.