[Effect of food on fluoride bioavailability]

The bioavailability of fluoride (F) is not known to be reduced by any food except for milk and milk products. Their effect on F bioavailability can, however, be reduced or altogether abolished by the ingestion of solid food. Solid food intake also enhances the extraction of F from poorly soluble compounds like CaF2. The reduction of F availability by milk is thought to be attributable to binding of F as milk curdles in the stomach. Improved utilization of F by solid food intake may be explained by the prolonged retention of the chyme in the upper gastrointestinal tract, which would leave more time for F to be released from curdling products and bound forms as e.g. CaF2. Simultaneous intake of F and food produces lower serum F levels; these are, however, sustained longer than in fasted subjects. The lower peak levels may well reduce the risk of enamel mottling, while the prolonged serum F levels may produce sustained F concentrations in the oral cavity by salivary F erection. These would prevent caries.