King Grub
2018-11-14, 10:20
RATIONALE:
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.
METHODS:
Healthy men (43±3 y; BMI: 23.4±0.4 kg/m2; n=12) and women (46±2 y; BMI: 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.
RESULTS:
Plasma phenylalanine and leucine concentrations rapidly increased following 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 h postprandial period averaged 56±1 and 53±1% in the women and men, respectively (P=0.145). Myofibrillar protein synthesis rates increased (Time P=0.010) from 0.035±0.004 and 0.030±0.002 %/h in the post-absorptive state (t-test P=0.319) to 0.045±0.002 and 0.034±0.002 %/h in the 5 h 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 (0-2 h) postprandial period when compared with men (Time×Sex P=0.001).
CONCLUSIONS:
There are no differences in post-absorptive 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 when compared with men.
J Clin Endocrinol Metab. 2018 Nov 12. The muscle protein synthetic response to whey protein ingestion is greater in middle-aged women when compared with men.
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.
METHODS:
Healthy men (43±3 y; BMI: 23.4±0.4 kg/m2; n=12) and women (46±2 y; BMI: 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.
RESULTS:
Plasma phenylalanine and leucine concentrations rapidly increased following 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 h postprandial period averaged 56±1 and 53±1% in the women and men, respectively (P=0.145). Myofibrillar protein synthesis rates increased (Time P=0.010) from 0.035±0.004 and 0.030±0.002 %/h in the post-absorptive state (t-test P=0.319) to 0.045±0.002 and 0.034±0.002 %/h in the 5 h 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 (0-2 h) postprandial period when compared with men (Time×Sex P=0.001).
CONCLUSIONS:
There are no differences in post-absorptive 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 when compared with men.
J Clin Endocrinol Metab. 2018 Nov 12. The muscle protein synthetic response to whey protein ingestion is greater in middle-aged women when compared with men.