CYP7A1 and obesity due to melanocortin 4 receptor deficiency: However, the results of experiments with rats show that iron supplementation during pregnancy can reduce plasma triglyceride levels in fetus and adult rats, and reduce the risk of metabolic diseases such as obesity by down-regulating the expression of genes involved in bile acid synthesis and fatty acid synthesis pathways, especially cholesterol 7α-hydroxylase and its upstream regulator liver X receptor α (44).