Effects of a 900-kcal liquid or solid diet on saliva flow rate and composition in female subjects

Eleven healthy females of normal weight participated in a study on the effects of two 900-kcal (5,548 kJ) diets, one solid and one liquid, given for 8-day periods. Unstimulated and stimulated whole saliva was collected before, during, between, and after the two different experimental periods. The dietary intake was recorded and evaluated for its content of energy and nutrients during normal and experimental periods. The 900-kcal liquid diet caused a reduction in saliva secretion rate, sialic acid, and phosphate concentrations and an increase in the sodium concentration as well as in the ratio of total protein to sialic acid. Chewing a 900-kcal solid diet restored saliva secretion and composition. The rate of dental plaque formation was increased by both 900-kcal diets, but more during the liquid period.