Co-ingesting milk fat with micellar casein does not affect postprandial protein handling in healthy older men. Issue 2 (April 2017)

• Record Type: Journal Article
• Authors: Gorissen, Stefan H.M.; Burd, Nicholas A.; Kramer, Irene Fleur; van Kranenburg, Janneau; Gijsen, Annemie P.; Rooyackers, Olav; van Loon, Luc J.C.
• Is Part Of: Clinical nutrition. Volume 36:Issue 2(2017:Apr.)
• Page Start: 429
• Page End: 437
• Publication Date: 2017-04
• Subjects: Muscle protein synthesis -- Fat -- Casein -- Leucine -- Sarcopenia; Critically ill -- Nutrition -- Periodicals; Diet therapy -- Periodicals; Parenteral feeding -- Periodicals; Enteral feeding -- Periodicals; Enteral Nutrition -- Periodicals; Parenteral Nutrition -- Periodicals; Metabolism -- Periodicals; Diétothérapie -- Périodiques; Alimentation parentérale -- Périodiques; Alimentation entérale -- Périodiques; Nutrition -- Périodiques; Diet therapy; Enteral feeding; Nutrition; Parenteral feeding; Electronic journals; Periodicals; Electronic journals; 615.854
• DOI: 10.1016/j.clnu.2015.12.011
• Languages: English
• ISSNs: 0261-5614

Abstract

Summary: Background & aim: Dietary protein digestion and absorption plays an important role in modulating postprandial muscle protein synthesis. The impact of co-ingesting other macronutrients with dietary protein on protein digestion and absorption and the subsequent muscle protein synthetic response remains largely unexplored. This study investigated the impact of co-ingesting milk fat with micellar casein on dietary protein-derived amino acid appearance in the circulation and the subsequent postprandial muscle protein synthetic response in healthy older men. Methods: Twenty-four healthy, older males (age: 65 ± 1 y, BMI: 25.7 ± 0.5 kg/m 2 ) received a primed continuous infusion of L-[ring- 2 H5 ]-phenylalanine and L-[1– 13 C]-leucine and ingested 20 g intrinsically L-[1– 13 C]-phenylalanine and L-[1– 13 C]-leucine-labeled casein with (PRO + FAT; n = 12) or without (PRO; n = 12) 26.7 g milk fat. Plasma samples and muscle biopsies were collected in both the postabsorptive and postprandial state. Results: Release of dietary protein-derived phenylalanine into the circulation increased following protein ingestion (P < 0.001) and tended to be higher in PRO compared with PRO + FAT (Time × Treatment P = 0.076). No differences were observed in dietary protein-derived plasma phenylalanine availability (52 ± 2 vs 52 ± 3% in PRO vs PRO + FAT, respectively; P = 0.868). Myofibrillar protein synthesis rates did not differ between treatments, calculated using either the L-[ring- 2 H5 ]-phenylalanine (0.036 ± 0.003 vs 0.036 ± 0.004 %/h after PRO vs PRO + FAT, respectively; P = 0.933) or L-[1– 13 C]-leucine (0.051 ± 0.004 vs 0.046 ± 0.004 %/h, respectively; P = 0.480) tracer. In accordance, no differences were observed in myofibrillar protein-bound L-[1– 13 C]-phenylalanine enrichments between treatments (0.018 ± 0.002 vs 0.014 ± 0.001 MPE, respectively; P = 0.173). Conclusion: Co-ingesting milk fat with micellar casein does not impair protein-derived phenylalanine appearance in the circulation and does not modulate postprandial myofibrillar protein synthesis rates. Clinical Trial Registration Number : NCT01680146 (http://www.clinicaltrials.gov/ )