Previous studies suggested that peptide absorption by peptide transporter 1 (PepT1) contributes to water absorption in the small intestine. Here, we aimed to apply this effect of peptides to a rehydration drink for the effective treatment of dehydration. We first prepared a whey peptide drink (WPD) in which the composition (whey peptides and Na+) was optimized for water absorption in the small intestine. We then evaluated the effectiveness of the WPD in an in vivo dehydration model. The results demonstrated the following: (1) the addition of whey peptides to a carbohydrate-electrolyte drink enhanced the rehydration effect in the rat dehydration model, i.e., it increased the plasma volume more quickly and more abundantly; and (2) the WPD was more effective for rehydration than a general sports drink. The WPD could be considered a new treatment option for the rapid alleviation of dehydration.
