Potentiation of magnesium-deficiency-induced foetotoxicity by concomitant iron deficiency and its prevention by adequate supply via drinking water.

Magnesium (Mg) and iron (Fe) deficiency frequently develop during pregnancy. Therefore these factors were studied alone (Mg-L, resp. Fe-L) or in combination (Mg-L/Fe-L) on 16 female and 8 male adult fertile Sprague-Dawley rats. The animals were offered a basal diet containing 30 per cent and 17 per cent of the rat's requirement for magnesium and iron, respectively, starting 21 days before mating (2:1) until 49 days after mating. Offspring were also kept on this regimen during a 3-week lactation period and 7 days post weaning. Drinking water was either enriched with 101 ppm Fe2+ (ferrous gluconate): Mg-L, or 365 ppm magnesium (magnesium-L-aspartate hydrochloride trihydrate, MAH): Fe-L, or with any: Mg-L/Fe-L or with both electrolytes: Controls. Fertility remained unaffected under these conditions. Clinically, Fe-L induced iron deficiency and growth retardation of offspring. Pronounced reproductive toxicity was elicited by Mg-L and was even potentiated by Mg-L/Fe-L. In the parental generation, too, adverse effects of Mg-L were aggravated by Mg-L/Fe-L despite the fact that no iron accumulation occurred. Bioavailability of iron was not impaired by magnesium as MAH. With respect to human pregnancy magnesium supplementation has higher priority over iron supplements. To improve tolerance and compliance both minerals are suggested to be taken simultaneously.