A new study involving more than 2,500 men suggests that the source of dietary protein may be linked to testosterone levels, with animal protein—particularly from dairy—associated with lower testosterone and plant protein linked to higher levels. The findings, published in a health research journal, add to a growing body of evidence examining how everyday food choices may influence male hormone profiles. Researchers cautioned that the observational nature of the study means it cannot establish causation, and that factors such as body composition, physical activity and overall diet quality could influence both protein source and hormone levels.
The study’s authors said the results raise intriguing questions about the relationship between nutrition and endocrine health, though they stressed that men should not alter their diets based on a single study. Independent experts noted that testosterone levels fluctuate naturally and are affected by numerous variables, including age, sleep and stress. They called for randomized controlled trials to clarify whether shifting protein sources—such as replacing dairy with legumes or nuts—produces measurable hormonal changes, and whether any such effects would be clinically meaningful for male health outcomes over time.
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