In a study published in Cancer Causes Control 2018, the relationship between caffeine consumption and blood concentration of sex hormones and sex hormone-binding globulins was evaluated (SHBG). The concentration of SHBG is the most important factor in determining the percentage of active steroid sexual hormones in circulation. By modulating the levels of sex steroid hormones, caffeine may act to prevent various pathological conditions in men, such as prostate cancer.
In the study, 1,410 men over the age of 20 were recruited. The consumption of coffee, tea and soft drinks containing caffeine was recorded using a food frequency questionnaire. The daily intake of caffeine was estimated by multiplying the concentration of caffeine per cup by the frequency of coffee, tea or soft drinks consumed daily. Serum hormone and SHBG levels were measured by immunoassay techniques.
The study found a positive relationship between coffee consumption and SHBG concentration while no association with SHBG was observed for the consumption of tea or soft drinks containing caffeine. The study therefore concludes that men who drink coffee more frequently may have a higher blood concentration of SHBG; however, there are no associations between circulating SHBG levels and caffeic-based non-alcoholic beverages.

Frey, Tanja, et al. “Consumption of caffeinated beverages and serum concentrations of sex steroid hormones in US men.” Cancer Causes & Control 29.1 (2018): 157-166.