תזונה ותוספים Co-ingestion of whey protein and casein in a mixed meal - demonstration of a more sus

[Mike Bikov]

Am J Physiol Endocrinol Metab. 2012 May 8. [Epub ahead of print]
Co-ingestion of whey protein and casein in a mixed meal - demonstration of a more sustained anabolic effect of casein.
Soop M, Nehra V, Henderson GC, Boirie Y, Ford GC, Nair KS.
Source

1Mayo Clinic.
Abstract

When consumed separately, whey protein (WP) is more rapidly absorbed into circulation than casein (Cas), which prompted the concept of rapid and slow dietary protein. It is unclear whether, when co-ingested as in milk, if these proteins have similar metabolic fates. We determined the rate of appearance across the splanchnic bed and the rate of disappearance across the leg of phenylalanine (Phe) from co-ingested intrinsically labeled WP and Cas. Either [(15)N]Phe or [(13)C-ring C(6)]Phe were infused in lactating cows and the labeled WP and Cas from their milk were collected. To determine the fate of Phe derived from different protein sources, eighteen healthy participants were studied after ingestion of one of the following: 1) [(15)N]WP, [(13)C]Cas and lactose; 2) [(13)C]WP, [(15)N]Cas and lactose; 3) lactose alone. At 80-120 min, the rates of appearance (Ra) across the splanchnic bed of Phe from WP and Cas were similar (0.068+0.010 vs 0.070+0.009 %/min, ns). At time 220-260 min, Phe appearance from WP had slowed (0.039+0.008 %/min, p<0.05) while Phe appearance from Cas was sustained (0.068+0.013 %/min). Similarly, accretion rates across the leg of Phe absorbed from WP and Cas were not different at 80-120 min (0.011+0.002 vs 0.012+0.003 %/min, ns) but at 220-260 min it was significantly lower for WP (0.007+0.002 %/min) for Cas (0.013+0.002 %/min) at 220-260 min. Early after meal ingestion, amino acid absorption and retention across the leg were similar for WP and Cas, but as rates for WP waned, absorption and assimilation into skeletal muscle were better retained for Cas.​

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