Studies on the postprandial thermogenic action of proteins and protein mixtures in rats

The postprandial thermogenic action of different proteins and their mixtures dependent on their biological value was estimated in rats by indirect calorimetry with special reference to the reproducibility of the evaluation of the postprandial metabolic rate. The absolute thermogenic action (related to the food energy intake) of casein, white-egg protein and gelatine, fed in combination with wheat starch (1:1), amounted to 11.4%, 14.5% and 17.8%, respectively. Mixtures of casein with gelatine (ratio 1:1 and 1:2) as well as the mixture of casein with glycine (in such amount as in the casein-gelatine mixture of 1:1) lead to a postprandial thermogenic action of 16.1%, 19.2% and 14.5%, respectively. If proteins of distinctly different biological value are compared an inverse correlation to their postprandial thermogenic action can be demonstrated which reflects partly theoretical approaches to the ATP yielding capacity, calculated from the amino-acid pattern of the proteins and their mixtures.