Effect of dietary fat on fluoride absorption and tissue fluoride retention in rats

The effect of dietary fat on fluoride toxicity was investigated in rats fed isoenergetic diets with graded levels of fat (0, 10%, 30% or 50% of energy) containing 400 ppm fluoride. Growth rate was depressed in all groups receiving fluoride but most severely in the 50% dietary fat group. Plasma, liver and femur fluoride concentrations were increased by increasing dietary fat. This was apparently due to increased absorption of fluoride, since urinary fluoride increased and fecal fluoride excretion decreased as fat intake was elevated. The enhancement of fluoride absorption by fat is believed to be due to the delaying effect of fat and fluoride on gastric emptying, thereby allowing more time for the fluoride to be absorbed from the stomach.