Table 4.

Recent studies related to infant protein digestion using in vivo approaches

Subjects	Description	Diet	Analysis	Reference
Mice	Male, weaning, n=6 per group	Beans and rice.	Chemical analysis of diet and feces. Protein digestibility-corrected amino acid scores.	[111]
	0 and 8-day-old	Colostrum and mature milk from lactating mice.	SDS-PAGE, western blot, and amino acid sequencing of stomach content.	[112]
Piglets	Fed from day 7 to 28, n = 28 per group	Adequate- or high-protein formulas.	Growth measurements, hormone assays, western blot, adipocyte diameter, real-time PCR of blood and adipose tissue.	[101]
	Fed from day 2 to 28, n = 18	Infant formula adapted to piglets.	Chemical analysis, SDS-PAGE, immunoblotting, ELISA, and LC-MS/MS of content from stomach, proximal jejunum, median jejunum, and ileum.	[102]
	Piglets weaned at 25-day-old and fed respective diets for 3 weeks, n = 6 per group	Diets high (26%) and low (18%) in protein and with or without two different sources of carbohydrates.	Chemical analysis for major bacterial metabolites from stomach, jejunum, ileum, caecum, proximal and distal colon.	[86]
	Piglets weaned at 17-day-old, and fed experimental diets from day 27 to 34, n = 5 per group	Casein diet, casein sesame expeller diet, or casein soya bean meal diet.	Chemical analysis of diet and ileum content for ileal digestibility calculation.	[100]
Human infants	Term, 4 to 12-day-old, n = 3	Expressed breast milk.	LC-MS/MS analysis of gastric content collected via a nasogastric tube.	[106, 107]
	Premature, 1 to 28-day-old, n = 56 in total	Human milk with an ultraconcentrated liquid human milk fortifier or a powder human milk fortifier.	Nutritional intake analysis, growth measurements, blood analysis.	[113]
	Birth to 12-month-old, n = 305 in total	Low-protein formula with probiotics, standard formula, or breast milk, and complementary foods.	Growth measurements, blood analysis for biomarkers of protein metabolism (blood urea nitrogen, insulin growth factor-1, insulinogenic amino acids).	[114]
	Premature, gestation <32 weeks, n = 60 in total	Breast milk with high-protein fortifier or low-protein fortifier.	Growth measurements, blood analysis for clinical chemical parameters (albumin, cystatin C, and urea).	[115]