Effect of concurrent calcium ingestion on intestinal absorption of fluoride.

It has been suggested that calcium interferes with absorption of fluoride and that it diminishes the effect this ion has of increasing the bone mass when taken orally. Normal volunteers were given a combination of fluoride and calcium carbonate or fluoride alone, and serum levels of fluoride were measured to determine the effect, if any, of the concomitant administration of calcium on absorption of fluoride. The results indicate that 1.3 g of calcium, as the carbonate, decreases the integrated blood fluoride values by 22%.