Effects of caffeine on fluoride, calcium and phosphorus metabolism and calcified tissues in the rat

This 6-week study was designed to determine the effects of graded doses of caffeine intake (3, 25 or 100 mg/kg per day) on the metabolic balance and t issue concentrations of fluoride, calcium and phosphorus in Sprague-Dawley rats. Caffeine intake did not affect the absorption, urinary excretion or b alance of fluoride, the plasma, bone or enamel concentrations of fluoride, nor the occurrence of incisor enamel fluorosis. Neither did it affect the m etabolism of calcium or phosphorus except that the urinary excretion of cal cium was increased. This effect, however, was not sufficient to influence s ignificantly calcium balance. The ash content of the femur epiphysis and bo ne mineral content of the tibia were significantly reduced only in the grou p exposed to the highest dose of caffeine. These effects on bone were not s ignificantly related to the balance of calcium or phosphorus. It was conclu ded that caffeine, even at an extremely high level of intake, has no detect able effect on the balance or tissue concentrations of fluoride, calcium or phosphorus in the rat. (C) 1999 Elsevier Science Ltd. All rights reserved.