Vitamin supplementation and breastfeeding
Previous studies have shown a protective role of maternal supplementation with B-vitamins and folic acid for childhood cancers, such as ALL, neuroblastoma, CNS tumors and germ cell tumors. Folate is important for cell division because of its role in de novo purine and pyrimidine synthesis, and also in the DNA repair mechanism. The rapid turnover of cancer cells entails greater DNA synthesis which, in turn, increases folate requirements to maintain this high rate of cell proliferation. Folate and other B-vitamins involved in 1-carbon metabolism are essential for the high-fidelity synthesis of DNA and activated methyl groups that are required for DNA methylation and regulation of chromatin structure. Genetic mouse models have shown that impaired 1-carbon metabolism interferes with genome integrity, which might explain the folate- and vitamin-related pathologies including the risk of childhood cancer, especially leukemia. In the present study, maternal vitamin supplementation during pregnancy was inversely associated with decreased risk, by around 20%, of childhood ALL, which is congruent with the results of large studies and the general recommendations that a healthy maternal diet around conception and early pregnancy based on the intake of B-vitamins (B9, B6, B12) is protective. Consistent with other studies, the present results also showed a decreased risk, by 20%, of ALL in children breastfed for more than 6 months. Breast milk contains immunologically active components, exosomes and exosomal RNAs, as well as anti-inflammatory defense mechanisms that influence the development and maturation of the immune system. It also contains antibodies that have a prebiotic effect and promote a more favorable infant gut microbiome. The more mature immune system of breastfed infants involves a greater abundance of natural-killer and stem cells compared to formula-fed infants. Encouraging breastfeeding into clinical practice seems to be a cost-efficient and beneficial public health measure.