The importance of fluoridated water to control caries is well recognized. Although the mode of action of fluoridated water is known (related to a slight increase in fluoride concentration in saliva/dental biofilm in individuals living in fluoridated areas), the kinetics of fluoride concentration in saliva after ingestion of food prepared with fluoridated water, either from fluoride remaining in the oral cavity after mastication, or from fluoride returning from salivary secretion is not known in details. Therefore, the aim of this study is to assess fluoride bioavailability after ingestion of food prepared with fluoridated water. The study will be in vivo, crossover and double blind, in which 12 adult volunteers will participate. In 4 experimental phases, volunteers will ingest: a. a typical Brazilian meal cooked with non-fluoridated water (<0.1 ppm F); b. a typical Brazilian meal cooked with fluoridated water (1 ppm F); c. non fluoridated water (<0.1 ppm F) and d. fluoridated water (1 ppm F). Immediately before and 5, 10, 15, 30, 45, 60, 120, 180 minutes after the ingestion, a blood sample will be collected by digital puncture, and a sample of unstimulated saliva will be collected. Fluoride concentration in the samples will be determined by an ion specific electrode adapted for microanalysis. Results will be analyzed by ANOVA, with significance limit of 5%.