Effects of aluminum hydroxide on fluoride and calcium metabolism.

In order to determine whether and to what extent aluminum affects the absorption of fluoride in man, a study of the effect of aluminum hydroxide on fluoride metabolism was carried out under strictly controlled dietary conditions. Relatively small amounts of aluminum hydroxide were used: 30 ml given three times daily, containing a total of 1.8 gm aluminum. Fluoride and calcium balances were determined in control studies and during the intake of aluminum hydroxide. The fluoride intake of approximately 4 mg/day was due to the fluoride content of the diet and the drinking water. A study was also carried out in patients with osteoporosis who received a high fluoride intake of approximately 50 mg/day of sodium fluoride therapeutically for osteoporosis. The intake of aluminum hydroxide was associated with a significant increase of the fecal fluoride and with a significant decrease of the net absorption of fluoride, by an average of 57%, irrespective of the intake of fluoride. The-plasma fluoride levels decreased by 41%. The fluoride balances were either negative or less positive. Relatively small amounts of aluminum hydroxide resulted in phosphorus depletion, in an increase of the urinary calcium, and in negative calcium balances.