Get numerous benefits from drinking coffee, including less risk of diabetes and a better body composition. A fascinating new study explores how coffee can prevent diabetes and shows that drinking it can influence free testosterone levels in men.
The study was published in Nutrition Journal and analyzed the effect of drinking 5 cups of coffee throughout the day for 8 weeks on hormone levels in middle-aged men and women. Researchers hoped to clarify why coffee has consistently been found to decrease type 2 diabetes risk. We know that caffeine consumption actually lowers insulin sensitivity, which suggests that caffeinated coffee should have a negative effect on insulin health.
The results were confusing but compelling for anyone interested in hormones. After 4 weeks, the men in the study experienced a significant increase in free testosterone and a decrease in free estrogen from drinking coffee. Free testosterone increased 76 percent and the testosterone to estrogen ratio increased 188 percent, indicating that coffee prevented the aromatization (a process in which testosterone is turned into estrogen) of testosterone. Unfortunately, both levels of both estrogen and testosterone returned to baseline by the 8th week of the study, indicating that the effect was not sustained.
This is the first study to test the relationship between coffee and sex hormones and the researchers don’t provide any reasons for the return to baseline hormone levels in the men during the second 4 weeks of the study. The effect of coffee on hormone levels in the women don’t help us come to any useful conclusions either—at 4 weeks both free testosterone and free estrogen were lower, whereas they returned to baseline by the end of the study.
Even though this study is a little disappointing in light of the promising midpoint results, a few things should be noted:
• The study used the same instant coffee beverage for the whole 8 weeks. Instant coffee is of poorer quality than coffee brewed from beans and contains fewer antioxidants.
• Using high-quality brewed coffee and rotating the degree of roasting used on coffee beans may produce different (hopefully better) results. Previous studies have shown the degree of roasting affects metabolism and body composition differently.
• There is consistent evidence that coffee drinking decreases diabetes risk and improves blood sugar management.
• Coffee drinking is associated with less risk of all-cause mortality and lower risk of cancer.
• Drinking caffeinated coffee has been shown to lead people to eat fewer calories, leading to weight loss. Coffee is thought to help modulate hormones that suppress hunger. It’s reasonable to suggest it influences the levels of other hormones such as testosterone as well.
• Coffee has been shown to improve vascular health, decrease risk of heart attack, and does NOT raise blood pressure over the long-term.
• Scientists have recently identified a specific gene polymorphism for heightened caffeine sensitivity. People with this genotype will be especially sensitive to caffeine and may want to avoid it.
Wedick, N., et al. The Effects of Caffeinated and Decaffeinated Coffee on Sex Hormone-Binding Globulin and Endogenous Sex Hormone Levels. Nutrition Journal. 2012. 11(86).