Effect of gastric contents on the bioavailability of fluoride in humans

The purpose of this study was to determine the effect of milk and solid foods on fluoride absorption. Ten adult volunteers received the following four treatments after being NPO for 8 hr: 1) 2.2 mg NaF, 2) 2.2 mg NaF and lunch, 3) 2.2 mg NaF and milk, and 4) lunch only. Samples of blood were taken at baseline and at up to 180 min after fluoride administration. Fluoride absorption was calculated for all four treatment groups. Milk was found to reduce fluoride absorption by 13%, while the presence of food reduced the absorption by 47%. The presence of food also delayed fluoride absorption, and significantly reduced the peak level of fluoride in serum.