Comparison of protein digestibility of human milk and infant formula using the INFOGEST method under infant digestion conditions.

Many improvements have been made to bring infant formula (IF) closer to human milk (HM) regarding its nutritional and biological properties. Nevertheless, the protein components of HM and IF are still different, which may affect their digestibility. This study aimed to evaluate and compare the protein digestibility of HM and IF using the infant INFOGEST digestion method. Pooled HM and a commercial IF were subjected to the infant INFOGEST method, which simulates the physiological digestion conditions of infants, with multiple directions, i.e., the curd state, SDS-PAGE, molecular weight distribution, free amino acid concentration, and in vitro protein digestion rate. HM underwent proteolysis before digestion, and tended to have a higher protein digestion rate with finer curds during gastric digestion, than the IF. However, multifaceted analyses showed that the protein digestibility of HM and IF was not significantly different after gastrointestinal digestion. In conclusion, the infant INFOGEST method showed that the digestibility of HM and IF proteins differed to some extent before digestion and after gastric digestion, but not at the end of gastrointestinal digestion. The findings of this study will contribute to the refinement of IFs with better protein digestibility in infant stomach.

A lower ratio of reduced to total albumin in serum is associated with protein nutritional status of pregnant women in Japan.

Protein-energy undernutrition is potentially prevalent among Japanese pregnant women, and biomarkers that objectively indicate the protein nutritional status during pregnancy may help in implementing appropriate protein supplementation to these women. We hypothesized that a serum parameter of pregnant women, the ratio of reduced to total albumin (reduced ALB ratio), would be associated with protein intake during pregnancy. The serum reduced ALB ratio of pregnant women was compared with protein intake and with gestation outcomes (gestation length and infant birth weight) in an observational study of 115 Japanese pregnant women. The serum reduced ALB ratio in the third trimester tended to be positively correlated with gestation length (P = .07). Infant birth weights tended to be different between protein intake tertiles (P = .09); the mean infant birth weight was higher in the third tertile compared with the first and second tertiles. The protein intake of pregnant women was significantly and positively correlated with the serum reduced ALB ratio in the second trimester. The serum reduced ALB ratio reflects protein nutritional status during pregnancy and may contribute to healthier gestation outcomes.

Nutritional Evaluation of Milk-, Plant-, and Insect-Based Protein Materials by Protein Digestibility Using the INFOGEST Digestion Method.

The INFOGEST method is a valuable tool for understanding and monitoring food digestion as an alternative to in vivo assays. However, few studies have compared animal and alternative protein sources in terms of protein quality using the INFOGEST method. This study aimed to evaluate the protein quality of milk-, plant-, and insect-based protein materials by in vitro protein digestibility and in vitro digestible indispensable amino acid score (DIAAS), following the INFOGEST method. Milk-based protein materials had the highest protein digestibility (86.1-90.8%), followed by soy (85.1%) and wheat (82.3%). These materials had significantly higher protein digestibility compared with zein (65.1%), cricket (63.6%), and mealworm (69.5%). Additionally, the mean values of in vitro DIAAS of milk-based protein materials (105.0-137.5) were higher than those of plant- and insect-based protein materials (1.9-91.0). Milk-based protein materials have higher protein quality than plant- and insect-based protein materials by the nutritional evaluation following the INFOGEST digestion method.