SALT INTAKE OF RATS FED DIETS DEFICIENT IN CALCIUM, IRON, MAGNESIUM, PHOSPHORUS, POTASSIUM, OR ALL MINERALS

Groups of nine to ten male rats fed diets deficient in calcium, iron, magnesium, phosphorus, potassium, or all minerals (i.e. no mineral mix) were given 0.3 m NaCl and water to drink. Over the first 30 days of dietary treatment, 0.3 m NaCl intake was progressively increased by deprivation of calcium or iron, unaltered by deprivation of phosphorus, and increased and then decreased by deprivation of magnesium, potassium, or all minerals. The changes in NaCl intake of rats deprived of potassium or all minerals were matched by corresponding changes in water intake. Water intakes of the other groups were unaltered. Thus, NaCl preference was increased by deprivation of calcium or iron, unaltered by deprivation of phosphorus, potassium, or all minerals, and decreased by deprivation of magnesium. To determine whether these changes were specific to the salty modality, animals maintained for 32 days on the diets deficient in calcium, iron, magnesium, and phosphorus received 24-h two-bottle tests with water vs. 2.5 mm saccharin, 2.5 mm citric acid, 0.368 mm sucrose octa-acetate, or 0.3 m NaCl. Relative to controls, rats deprived of calcium drank less 2.5 mm saccharin, those deprived of magnesium drank less 0.3 m NaCl, and those deprived of calcium or iron drank more 0.3 m NaCl. These results show that different mineral deficiencies have different effects on NaCl intake. They argue against the hypothesis that animals deprived of any mineral develop a chronic appetite for salt. © 1992.