TNF and major depressive disorder: Collectively, data from previous studies in healthy and sarcopenic older adults and our exploratory analysis in pre-frail older adults suggest that leucine-enriched protein supplementation and exercise combination improve physical function, depression, perceived health, body composition such as FFM and body cell mass, and overall inflammation as evident by reduced IL-6 and TNF-α (11, 18, 46–48, 50, 62).