Higher muscle protein synthesis rates following ingestion of an omnivorous meal compared with an isocaloric and isonitrogenous vegan meal in healthy, older adults

BACKGROUND: Plant-derived proteins are considered to have lesser anabolic properties when compared with animal-derived proteins. The anabolic properties of isolated proteins do not necessarily reflect the anabolic response to the ingestion of whole-foods. The presence or absence of the various components that constitute the whole-food matrix can strongly impact protein digestion and amino acid absorption and, as such, modulate post-prandial muscle protein synthesis rates. So far, no study has compared the anabolic response following ingestion of an omnivorous versus a vegan meal. OBJECTIVE: To compare post-prandial muscle protein synthesis rates following ingestion of a whole-food meal providing 100 g lean ground beef versus an isonitrogenous, isocaloric whole-food plant-based meal in healthy, older adults. METHODS: In a randomized, counter-balanced, cross-over design, 16 older (65-85 y) adults (8 males, 8 females) underwent 2 test days. On one day, participants consumed a whole-food omnivorous meal containing beef as the primary source of protein (0.45 g protein·kg BM; MEAT). On the other day, participants consumed an isonitrogenous and isocaloric whole-food vegan meal containing unprocessed plant-based whole-foods (PLANT). Primed continuous L-[ring- C ]-phenylalanine infusions were applied with blood and muscle biopsies being collected frequently for 6 h to assess post-prandial plasma amino acid profiles and muscle protein synthesis rates. Data are presented as means±SDs and were analyzed by two way-repeated measures ANOVA and paired-samples t-tests. RESULTS: MEAT increased plasma essential amino acid concentrations more than PLANT over the 6 h post-prandial period (incremental area under curve 87±37 vs 38±54 mmol·6 h·L respectively; P-interaction<0.01). Ingestion of MEAT resulted in ~47% higher post-prandial muscle protein synthesis rates when compared to the ingestion of PLANT (0.052±0.023 and 0.035±0.021 %·h , respectively; paired-samples t-test: P=0.037). CONCLUSION: Ingestion of a whole-food meal containing beef, results in greater post-prandial muscle protein synthesis rates when compared to the ingestion of an isonitrogenous whole-food plant-based meal in older adults. https://clinicaltrials.gov/study/NCT05151887. CLINICAL TRIAL REGISTRATION: Https://clinicaltrials.gov/study/NCT05151887.