Table 2.

Protein-derived amino acid availability in the circulation and postprandial rates of muscle protein synthesis (MPS) after ingestion of isolated protein sources and whole foods healthy young and older adults

	Protein amount (g)	Dietary amino acid availabilitya	MPS responseb	References
Intrinsically labeled food studies
Casein	20	55% (Phe)	1.51d	[74]
Beefc	30	64% (Phe)	1.90d	[33]
Egg whitec	18	66% (Leu)	1.90e	[35]
Whey	35	59% (Phe)	2.09d	[75]
Skim milkc	30	57% (Phe)	2.37d	[33]
Whole eggc	18	68% (Leu)	2.70e	[35]
Whey	20	58% (Phe)	No basal	[76]
Casein	20	53% (Phe)	No basal	[76]
Casein hydrolysate	20	55% (Phe)	No basal	[76]
Non-labeled food studies
Wheat protein hydrolysate	60		1.40d	[31]
Soyc	40		1.40d	[77]
Pork	36		1.63d	[34]
Beefc	36		2.00d	[78]
Milk protein concentrate	20		2.48d	[79]
Whey	20		3.00d	[79]

^aFractions of dietary protein derived amino acids that appeared in the circulation (percentage) throughout 0–5 h or 0–6 h postprandial periods. The data were based on an orally ingested leucine (Leu) or phenylalanine (Phe) tracers intrinsically labeled into food sources and designated by their respective amino acid in parentheses

^bPostprandial rates of MPS expressed as fold change from reported basal rates (when available)

^cIndicates protein ingestion after an acute bout of exercise

^dIndicates rates of MPS were measured using labeled phenylalanine tracer incorporation in muscle tissue

^eIndicates rates of MPS were calculated using labeled leucine tracer incorporation into muscle tissue