Metabolic kinetics and muscle and brain health markers in older adults, and the role of age and presence of chronic morbidities: A large cross-sectional cohort study

Older adults are at risk for muscle and cognitive function decline during advanced aging, but the underlying metabolic mechanisms and the role of aging-associated chronic morbidities remain unclear. In the present study, we examined whether protein and amino acid kinetics in older adults with and without chronic morbidities are different when 50–70 and 70–90 of age and related to markers of muscle and brain health declines. In a large cross-sectional observational study, 575 older adults from 12 trials (2014–2022) were stratified based on their age (50-70y vs. 70-95y) and the presence of chronic morbidities. The main outcomes were whole-body production (WBP) and interconversions of amino acids by stable amino acid tracers, body composition, and muscle and cognitive performance. Additionally, the association between metabolic markers and muscle and brain health was assessed. Overall lower muscle strength, muscle and fat mass, and cognitive function (p