Change in vitamin B12 level in breast milk according to the week of delivery in Turkish women

97 Yesildal, Vitamin B12 level in breast milk / doi: 10.14744/ijmb.2020.82905 B12 is an essential nutrient that plays a critical role in the reactions of folate-dependent single-carbon transport, including the conversion of homocysteine to methionine, the conversion of methylmalonyl coenzyme A to succinyl coenzyme A, and nucleic acid synthesis [5] Therefore, vitamin B12 is very important for growth and development in the fetal and infantile periods [6] The transfer of vitamin B12 from blood to the mammary gland epithelium occurs through receptor-mediated endocytosis [7]. It is then secreted from the gland epithelium into the milk. Vitamin B12 is mostly bound to apo-haptocorrin in breast milk [8]. The vitamin B12 concentration in breast milk has been shown to be lower in mothers who are vitamin B12 deficient [9]. The liver of a newborn delivered of a normal, healthy mother contains 25-30 μg of vitamin B12. However, if the mother has a low vitamin B12 level, the amount of vitamin B12 in the liver of the newborn infant decreases to 2-5 μg. The recommended dietary allowance (RDA) of vitamin B12 for the growth of tissues and neurological development is 0.4 μg [7, 10]. The recommended daily intake of vitamin B12 for breastfeeding mothers is 2.8 μg [11]. The aim of this study was to investigate whether the vitamin B12 content of breast milk differed according to the week of delivery (preterm, term) and how the vitamin B12 content in breast milk changed during the first 28 days of lactation and to assess the need for supplementary vitamin B12. Materials and Methods Infants born before the 34th gestational week were classified as preterm, those delivered between the 34th and 37th weeks were grouped as late preterm, and the term delivery group consisted of infants born after the 37th week. A total of 30 mothers were included in the study group, with 10 in each of the 3 groups of preterm, late preterm, term delivery. Milk samples were collected from these mothers on postpartum days 3, 7, and 28. The milk sample taken on the 3rd day was defined as colostrum, the sample taken on the 7th day was defined as transition milk, and the sample taken on the 28th day was defined as mature milk. Thus, a total of 30 milk samples were collected for each delivery group. Multiple pregnancies and congenital malformations were excluded from the study. Each mother used a breast pump (Medela Mini Electric; Medela AG, Baar, Switzerland) between 8:00 and 9:00 in the morning to drain a single breast, and 4 mL of this milk was collected into tubes, thereby eliminating any error due to differences between foremilk and hindmilk. The tubes were centrifuged at 2000g for 10 minutes at +4°C. Since the upper fat layer would interfere with the analysis, the supernatant below the fat layer was accessed with a fine-tip syringe and the samples were aliquoted for vitamin B12 analysis. A total of 90 breast milk samples were stored at -80°C until analysis. The statistical power was calculated as 86% with an alpha error of 0.05 and an effect size of 0.8 (G*Power 3.1.9.4 software; Faul, F., Erdfelder, E.). Vitamin B12 measurements were performed on a Siemens Advia Centaur XP autoanalyzer (Siemens Healthineers GmbH, Erlangen, Germany). Analysis of variance (ANOVA) and post hoc Tukey tests were used for group comparisons. The Kruskal-Wallis test was used for the analysis of nonparametric data. P<0.05 was considered statistically significant. This study was approved by the Gazi University Clinical Research Ethics Committee on March 9, 2015 (Approval number: 2015/120). Informed consent was obtained from all of the patients included in this study. The study was conducted and the data were collected according to the ethical principles of the Declaration of Helsinki.