The effects of added dietary iron in various forms on mice inoculated with Salmonella typhimurium

The susceptibility of mice to intraperitoneal infection with 10(4.8) living bacteria of three strains of Salmonella typhimurium was measured in groups fed either a basal, nutritionally adequate diet or the same diet to which had been added ferric iron in one of six forms: ferric sulphate or chloride (FeS), ferric ethylenediaminetetra-acetate (FeE), ferric nitrilotri-acetate (FeN), ferric fructose (FeF), ferric diethylenetriaminepenta-acetate (FeT) and ferric ethylenediamine di (O-hydroxyphenylacetate) (FeD). FeN and FeF significantly increased the survival rate of male but not female mice. This protective effect of FeN was not influenced by its concentration in the diet over the range tested, 25 to 800 mg of Fe per kg of diet. FeN had to be given a week before infection to produce the effect and it was associated with a reduced rate of multiplication of salmonellae. FeE significantly decreased the survival rate of both male and female mice, and greatly reduced the survival time of mice that died. The deleterious effect of FeE increased with its concentration in the diet and with the time for which it had been fed, and it was associated with very rapid bacterial multiplication. FeT gave results similar to those of FeE, while FeS and FeD had hardly any effect.