When liquids are thickened to swallow safely, thirstiness sensation might not be quenched. In this study, we investigated how drinking water, thickened water, or not drinking influences body hydration and thirstiness sensation. Forty-one healthy participants attended four 3 h sessions with different stimulus provided: nothing, water, thickened water A (gum-based thickener), or thickened water B (starch-based thickener). The hydration status (oral moisture and urinary osmolality), self-reported dimensions (thirst sensation, dry mouth sensation, and desire to drink), and hunger feeling were measured at 0, 90, and 180 min, respectively; after 180 min, water was administered ad libitum. The results show no significant changes in oral mucosa hydration over time. The urine osmolality values showed differences in body hydration depending on whether they had ingested water and on the type of thickened water (lower for thickener B). Thirstiness, dry mouth, and the desire to drink water after having the stimuli differed significantly from when no stimuli were given. Low liking was related to longer consumption time and more swallows, especially for thickened water B. At the end of the study, beyond the differences among three behavioral clusters, ad libitum water intake increased if no stimulus or thickened water B were administered. Hunger sensation varied over time, but not among stimuli. In conclusion, in the fast situation (no drink), thickened water helped maintain body hydration, although compared to water it were more disliked and, in comparison with water, right after their consumption did not decrease the dry mouth sensation. Therefore, although thickeners seem effective for hydrating and calming thirstiness, their poor liking needs to be improved in the design of dysphagia thickeners to improve their diet adherence.

This project and the contract of author R.P. were funded by a regional government grant (Conselleria de Innovación, Universidades, Ciencia y Sociedad Digital SEJIGENT/2021/0242 de Innovación, Universidades, Ciencia y Sociedad Digital SEJIGENT/2021/0242, Generalitat Valenciana).

With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX 2021-001189-S)

Peer reviewed