Study Links Higher Animal Protein Intake to Lower Testosterone Levels

Men concerned about their testosterone levels might want to examine their diets, according to a recent Finnish study. Research published in the journal Reproduction indicates that higher consumption of animal protein is associated with lower testosterone levels, whereas a greater intake of plant-based protein correlates with increased testosterone.

The study, which analyzed the dietary habits of 2,546 men aged between 42 and 60, found that men consuming the most animal protein and the least plant protein had significantly lower testosterone and sex hormone-binding globulin (SHBG) levels compared to those with the opposite dietary pattern.

Specifically, men with the highest intake of animal protein and lowest intake of plant protein had 1.2 nmol/L less testosterone. This represents approximately an 8% difference for an average man in his early 40s, based on data from other studies on normal testosterone levels. Conversely, men with the highest plant protein intake and lowest animal protein intake had 1.1 nmol/L higher testosterone, about a 7% increase for the same demographic.

Researchers noted that individuals who consumed more animal protein also tended to have higher BMIs, were more likely to smoke, consumed more alcohol, and had a higher prevalence of diabetes. In contrast, those who consumed more plant-based protein were associated with greater physical activity, higher fiber intake, more consumption of fruits and vegetables, and lower rates of smoking and saturated fat intake.

The study's authors suggest that plant protein may help reduce inflammation, a condition linked to decreased testosterone secretion. Plant-based protein sources like legumes, nuts, seeds, and whole grains offer fiber and antioxidants, while animal proteins, particularly red and processed meats, can be high in saturated fat, which has been linked to various health issues including heart disease and certain cancers. Despite the potential benefits of plant-based protein, animal sources remain the primary protein intake for many people in the U.S.