Lois Kramer

Effect of aluminum hydroxide on fluoride metabolism

Aluminum inhibits intestinal absorption of fluoride in animals but little information is available about man. To determine whether and to what extent aluminum affects fluoride absorption in man, effects of aluminum hydroxide on fluoride metabolism were studied under controlled dietary conditions. Relatively small amounts of aluminum hydroxide were used (30 ml three times daily, containing a total of 1.8 gm aluminum, were given for several weeks). Fluoride balances were determined in control studies and during the intake of aluminum hydroxide. The fluoride intake was the fluoride content of the diet and the drinking water. Two studies were also carried out on a high‐fluoride intake. The use of aluminum hydroxide was associated with an increase in fecal fluoride excretion and a decrease in net absorption of fluoride regardless of the intake of fluoride, calcium, phosphorus, or magnesium. Urinary fluoride decreased during aluminum hydroxide ingestion. Our studies show that relatively small amounts of aluminum hydroxide inhibit intestinal absorption of fluoride in man.

EFFECT OF CALCIUM, PHOSPHORUS, MAGNESIUM, AND ALUMINUM ON FLUORIDE METABOLISM IN MAN*

The studies of the interaction of fluoride with minerals in man have shown that: 1. in contrast to observations made in animals, the high intake of calcium, phosphorus, and magnesium in amounts that can be used in humans did not inhibit the intestinal absorption of fluoride in man; 2. the lack of effect of added calcium, given in divided doses, on the intestinal absorption of fluoride has relevance for the use of a high calcium intake during fluoride therapy for osteoporosis; 3. aluminum as the hydroxide, commonly used as an antacid in clinical medicine, significantly decreases the intestinal absorption of fluoride. This inhibitory effect, in conjunction with the known effects of aluminum-containing antacids in causing calcium loss as a consequence of phosphorus depletion, may contribute to the development of skeletal demineralization.

Effect of aluminum hydroxide on plasma fluoride and fluoride excretion during a high fluoride intake in man

Abstract A study was carried out in man to investigate the effect of small doses of aluminum hydroxide (30 ml three times daily, containing a total of 1.8 g aluminum) on plasma fluoride levels. In control studies, a 15 mg dose of fluoride as sodium fluoride was given by mouth three times daily and plasma fluoride levels were determined 1, 2, and 4 hr after each dose. In the experimental studies an oral dose of aluminum hydroxide was given together with each dose of sodium fluoride. Plasma fluoride levels were determined at the same time intervals as in control studies. Urinary fluoride was determined on 24-hr urine collections in both study phases. Following each dose of fluoride a distinct rise and subsequent gradual fall of plasma fluoride with time was noted. Administration of aluminum hydroxide markedly decreased plasma fluoride levels at all time intervals, the average decrease being 41%. Urinary fluoride also decreased significantly, by 51%. This study has shown that relatively small doses of aluminum hydroxide significantly decrease both plasma and urinary fluoride levels.

Factors Influencing Calcium Balance in Man

Calcium balance studies are time-consuming and tedious to perform. They also require strictly controlled study conditions, namely a constant dietary intake, completeness of collections of excreta, analyses of calcium intake as well as urinary and fecal excretions. These balances have to be determined for relatively long periods of time in order to obtain interpretable data because of the time required for adaptation to a given calcium intake. Another reason for employing long-term balance studies is the fact that passage of minerals, including calcium, through the intestine may be considerably delayed [2,38]. Despite these difficulties and the unavoidable errors inherent in determining calcium balances, the state of calcium metabolism can be quite reliably assessed by determining the intake and excretion of calcium in urine and stool. The loss of calcium in sweat is usually not monitored, and calcium balances must therefore be considered as maximal values.