Change in maternal Hb was not different between the intervention and control groups with higher increases among mothers with anemia compared to all mothers.<h4>Conclusion</h4>Nutrition education can positively influence knowledge and potentially complementary feeding, while further measures may be required for beneficial effects on anemia.<h4>Trial registration</h4>The study was registered prospectively at the German Clinical Trials Register (DRKS; DRKS-ID DRKS00012842) on November 27, 2017. The gene discussed is GSTM1; the disease is anemia (phenotype).