O011 - AGE-RELATED DECLINES IN POSTPRANDIAL AMINO ACID INTRACELLULAR DISPOSAL ACROSS YOUNG-OLD TO OLDER-OLD ADULTS

O011

AGE-RELATED DECLINES IN POSTPRANDIAL AMINO ACID INTRACELLULAR DISPOSAL ACROSS YOUNG-OLD TO OLDER-OLD ADULTS

S. B. Knezek^1,*, M. C. Kang¹, L. Rupp¹, V. Huettl¹, L. E. Ruebush¹, N. E. Deutz¹, M. P. Engelen¹ on behalf of Center for Translational Research in Aging and Longevity

¹Texas A&M University, College Station, United States

Rationale: Sarcopenia, age-related muscle loss, is often treated with dairy proteins (e.g., whey protein, WP). Plant-based proteins (soy, SP; pea, PP) are gaining interest, but their effect on intracellular amino acid metabolism in older adults is unclear. We used a novel stable-isotope pulse to compare WP, SP, and PP to study age effects on anabolic response and essential/non-essential amino acid (EAA/NEAA) disposal.

Methods: 32 participants (young-old: 69y, middle-old: 78y, older-old: 87y) completed a randomized, single-blind, crossover study on four non-consecutive study days. They consumed 45g of whey protein (WP), soy protein (SP), pea protein (PP), or water (postabsorptive state) via sip feeding every 20 minutes for 5 hours. 3 hours into feeding, an intravenous (IV) administration of a stable-isotope pulse containing amino acids to assess prandial amino acid kinetics and intracellular anabolic responses. Blood samples were collected pre/post pulse, and tracer enrichment was analyzed by LC-MS/MS. Data are estimated means (µmol/min) [95% CI] (+/-1 SD from the mean age) to dichotomize groups; stats by GLMM with lean body mass, sex, and age as fixed-effects.

Results: EAA disposal was reduced as age increased for several EAA (i.e., histidine (p=0.012), methionine (p=0.001), phenylalanine (p<0.001), and tryptophan (p=0.003)), and NEAA (i.e., arginine (p<0.001), glycine (p<0.001), and taurine (p<0.001)). Intracellular anabolic response (net protein synthesis) decreased with increasing age (p=0.045), independent of protein source.

Conclusion: Increasing age leads to reduced net protein synthesis and impaired amino acid disposal for most amino acids, regardless of dairy or plant-based protein source. This suggests that with aging, the ability to metabolize and utilize dietary protein decreases, highlighting the need to account for age when designing nutritional interventions for muscle maintenance.

Disclosure of Interest: S. Knezek: None declared, M. Kang: None declared, L. Rupp: None declared, V. Huettl: None declared, L. Ruebush: None declared, N. Deutz: None declared, M. Engelen Grant / Research Support from: WoodNext Foundation