Zinc supplementation to protein-deficient diet in CO-exposed mice decreased fetal mortality and malformation.

In developing countries, diet during pregnancy is frequently low in both protein and zinc contents and exposure to CO is common because of environmental pollution and smoking. This study was conducted to evaluate whether zinc supplementation ameliorates fetal mortality and malformations in protein-deficient, CO-exposed mice. Pregnant mice of the CD-1 strain were maintained on 17% (reference) or 9% protein diets mixed with deficient, normal, or supplemental zinc throughout gestation. The dams in each dietary group were exposed to air (control) or 500 ppm CO in air in environmental chambers from gestation days 7-18. As compared to the control group (normal protein, normal zinc), the incidence of fetal mortality was 66.8% and 57.2% higher, respectively, and malformation incidence was 74.4% and 72.4% higher (0 and 500 ppm CO, respectively) in mice fed both deficient protein-zinc diets. However, the highest malformation rate was observed in the group with normal protein, deficient zinc (96% mortality in both 500 and 0 ppm CO, as compared to the reference group, p < 0.0001). The fetal mortality rate was -3.5% (0 ppm CO) and 25.4% (500 ppm CO) lower in zinc-supplemented, protein-deficient groups compared to the control group. There was a significant negative association between fetal zinc concentrations and fetal malformations (p < or = 0.001). The result of this study might be relevant to populations that are exposed to CO and or consume marginal zinc and protein diets during gestation.