Ingestion of a variety of non-animal-derived dietary protein sources results in diverse postprandial plasma amino acid responses which differ between young and older adults.

Whole-body tissue protein turnover is regulated, in part, by the postprandial rise in plasma amino acid concentrations, although minimal data exist on the amino acid response following non-animal-derived protein consumption. We hypothesised that the ingestion of novel plant- and algae-derived dietary protein sources would elicit divergent plasma amino acid responses when compared with vegan- and animal-derived control proteins. Twelve healthy young (male [m]/female [f]: 6/6; age: 22±1 y) and 10 healthy older (m/f: 5/5; age: 69±2 y) adults participated in a randomised, double-blind, crossover trial. During each visit, volunteers consumed 30 g protein from milk, mycoprotein, pea, lupin, spirulina or chlorella. Repeated arterialised venous blood samples were collected at baseline and over a 5 h postprandial period to assess circulating amino acid, glucose, and insulin concentrations. Protein ingestion increased plasma total and essential amino acid concentrations ( P <0.001), to differing degrees between sources ( P <0.001), and the increase was further modulated by age ( P <0.001). Postprandial maximal plasma total and essential amino acid concentrations were highest for pea (2828±106 and 1480±51 µmol·L -1 ) and spirulina (2809±99 and 1455±49 µmol·L -1 ), and lowest for chlorella (2053±83 and 983±35 µmol·L -1 ) ( P <0.001), but were not affected by age ( P >0.05). Postprandial total and essential amino acid availabilities were highest for pea, spirulina and mycoprotein, and lowest for chlorella (all P <0.05), but no effect of age was observed ( P >0.05). The ingestion of a variety of novel non-animal-derived dietary protein sources elicits divergent plasma amino acid responses, which are further modulated by age.