How to quench your thirst. The effect of water-based products varying in temperature and texture, flavour, and sugar content on thirst

The sensation of thirst plays an important role in the consumption of water or other fluids to rehydrate the body in order to keep bodily functions working properly. An increase in saliva secretion, wetting the mouth by ingestion of liquids, and cooling and sour components in products can alleviate this sensation already before absorption of fluids by the body. This study aimed to investigate the thirst-quenching ability of water-based products differing in temperature and texture (cold solids and cool liquids), flavour (flavoured and non-flavoured) and sugar content in two consecutive experiments. The first experiment tested four products of 10 ml each (flavoured popsicles, flavoured beverages, ice cubes, and water). 45 healthy, thirsty participants (8 men and 37 women, mean age 25.7 years SD ± 6.6) were randomly assigned to a flavour group representing the flavour of the popsicles and beverages: mint, lemon, raspberry. Each flavour group tasted all four products (popsicles, beverages, water, ice cubes) in four sessions on consecutive days. Participants rated their thirst and four attributes (flavour intensity, thirst-quenching, refreshing, saliva stimulating) during 3 min of consumption on a 100 mm VAS scale and ranked all four products on thirst-quenching ability at the end of the last session. The second experiment was performed similarly (n = 61, 6 men and 55 women, mean age 23.5 years SD ± 2.87), but used sugar-reduced popsicles to compare to the regular popsicles from the first experiment. In addition, saliva was collected before and after consumption. In the first experiment, cold solid (55.8 ± 0.99) and flavoured (55.9 ± 0.95) products were found to be more thirst-quenching than cool liquid (52.8 ± 0.96) and non-flavoured products (52.8 ± 0.96). The second experiment confirmed that saliva production increased upon consumption of these popsicles, with an increase of saliva weight from 1.7 g SD ± 0.15 before consumption to 2.0 SD ± 0.22 after consumption. Sugar-reduced popsicles were similar in thirst-quenching ability compared to regular popsicles. Overall, cold, solid, flavoured products (such as popsicles) performed best in quenching thirst, and it appeared that sugar-reduction in these products to create healthier alternatives can be achieved without compromising on thirst-quenching abilities. These results can be useful for optimisation of products to alleviate thirst in daily life, as well as in clinical settings for patients where fluid restriction is needed.