Introduction: The effects of protein consumption on overall human health and longevity remain one of the most controversial issues in nutrition science to date. Aim: To evaluate the association between dietary protein intake and psychological distress, in people aged >65 years of age, living in insular Greece. Methodology: Data from older people living in 20 Greek islands, from the MEDiterranean Islands Study (MEDIS) (n=2,221) population-based cross-sectional study were used. Anthropometric, clinical and socio-demographic and lifestyle characteristics, and protein consumption (total, animal, plant) consumed based on validated FFQ, were derived through standard procedures and questionnaires. Psychological distress was assessed as a combined variable representing symptoms of depression and anxiety. Results: Animal protein, but not plant protein intake, was associated with higher PDS following adjustment for age, sex, education level, Mediterranean diet adherence and physical activity (b±SE: 0.403 ± 0.090, p=0.003). Following analysis by Mediterranean diet adherence level, among low adherers, animal protein intake was positively associated with Psychological Distress (b±SE: 1.119 ± 0.174, p=0.008); no associations were observed in moderate or high adherence groups or as regards plant protein intake and Psychological Distress. Conclusions: The present study suggests that plant protein sources form an important part of the overall dietary pattern and that low to moderate red meat intake within a Mediterranean diet pattern may be associated with lower Psychological Distress.