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- Title
The Muscle Protein Synthetic Response to Whey Protein Ingestion Is Greater in Middle-Aged Women Compared With Men.
- Authors
Horstman, A M H; Kouw, I W K; van Dijk, J W; Hamer, H M; Groen, B B L; van Kranenburg, J; Gorissen, S H M; van Loon, L J C; Horstman, Astrid M H; Kouw, Imre W K; van Dijk, Jan-Willem; Hamer, Henrike M; Groen, Bart B L; van Kranenburg, Janneau; Gorissen, Stefan H M; van Loon, Luc J C
- Abstract
<bold>Rationale: </bold>Muscle mass maintenance is largely regulated by the postprandial rise in muscle protein synthesis rates. It remains unclear whether postprandial protein handling differs between women and men.<bold>Methods: </bold>Healthy men (43 ± 3 years; body mass index, 23.4 ± 0.4 kg/m2; n = 12) and women (46 ± 2 years; body mass index, 21.3 ± 0.5 kg/m2; n = 12) received primed continuous infusions of l-[ring-2H5]-phenylalanine and l-[ring-3,5-2H2]-tyrosine and ingested 25 g intrinsically l-[1-13C]-phenylalanine-labeled whey protein. Blood samples and muscle biopsies were collected to assess dietary protein digestion and amino acid absorption kinetics as well as basal and postprandial myofibrillar protein synthesis rates.<bold>Results: </bold>Plasma phenylalanine and leucine concentrations rapidly increased after protein ingestion (both P < 0.001), with no differences between middle-aged women and men (Time × Sex, P = 0.307 and 0.529, respectively). The fraction of dietary protein-derived phenylalanine that appeared in the circulation over the 5-hour postprandial period averaged 56 ± 1% and 53 ± 1% in women and men, respectively (P = 0.145). Myofibrillar protein synthesis rates increased (Time, P = 0.010) from 0.035 ± 0.004%/h and 0.030 ± 0.002%/h in the postabsorptive state (t test, P = 0.319) to 0.045 ± 0.002%/h and 0.034 ± 0.002%/h in the 5-hour postprandial phase in middle-aged women and men, respectively, with higher postprandial myofibrillar protein synthesis rates in women compared with men (t test, P = 0.005). Middle-aged women showed a greater increase in myofibrillar protein synthesis rates during the early (0 to 2 hours) postprandial period compared with men (Time × Sex, P = 0.001).<bold>Conclusions: </bold>There are no differences in postabsorptive myofibrillar protein synthesis rates between middle-aged women and men. The myofibrillar protein synthetic response to the ingestion of 25 g whey protein is greater in women than in men.
- Publication
Journal of Clinical Endocrinology & Metabolism, 2018, pN.PAG
- ISSN
0021-972X
- Publication type
journal article
- DOI
10.1210/jc.2018-01734