Plant vs Animal Protein: New Study Reveals Surprising Links to Men's Testosterone Levels

The type of protein men eat could influence their hormone levels, according to new research from the University of Eastern Finland that has uncovered intriguing differences between animal-based and plant-based foods. Published in the International Journal of Food Sciences and Nutrition, the study analyzed dietary records and blood samples from 2,546 Finnish men aged 42 to 60, examining how protein intake relates to testosterone, a hormone important for muscle strength, bone health and sexual function. Researchers found that men consuming the most animal protein had testosterone levels averaging 1.2 nmol/L lower than those consuming the least, while men with the highest plant protein intake had levels approximately 1.1 nmol/L higher than those with the lowest intake. Dairy protein showed a particularly clear association with lower testosterone, whereas protein from vegetables and other non-grain plant sources was associated with higher levels. Interestingly, meat protein alone was not significantly associated with total testosterone. Although the findings suggest that protein sources may relate differently to hormonal health, researchers caution that the differences were relatively small and the study cannot prove that changing one's diet directly raises or lowers testosterone. The discovery encourages further investigation into how everyday foods such as beans, lentils, vegetables, dairy products and meat may influence men's long-term metabolic and hormonal well-being.