Unique content of breastmilk: neurotrophic growth factors in breastmilk at 2 years and beyond.

The aim of our study was to show the presence of neurotrophic factors in breast milk that have a significant impact on neurocognitive development of children aged two years and beyond. Mothers expressed at least 5 mL of breast milk into sterile containers when their children 18, 24, and ≥ 25 months of age, and then specimens were transferred to Eppendorf tubes and stored at -20 °C. One day before the analysis, specimens were kept at +4 °C and then thawed at room temperature to prepare them for analysis. Brain-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF), and S100B neurotrophic growth factor levels were analyzed using the sandwich enzyme-linked immunosorbent assay (ELISA) principles. Sixty-two mothers with children aged 18 months were included in the study. The mean age of the mothers was 33.4 (± 0.71) years. Due to the detection limits of the commercial kits, BDNF and S100B analyses could not be conducted. Therefore, only GDNF was analyzed. The presence of GDNF was found in the breast milk samples taken at 18, 24, and ≥ 25 months, and the median (min max) values were 315,505 ng/mL (193,067 750,718), 316,721 ng/mL (161,278 l-752,252), and 564,577 ng/mL (238,528-781,104) respectively. There were no significant differences between GDNF levels of breast milk samples collected from the same mother at the three different time points (18, 24, and ≥ 25 months) (p = 0.278).    Conclusion: Our study was the first to show the presence of neurotrophic factors in the breast milk of mothers with healthy children over one year of age. Our results provide evidence-based data on the importance of breastfeeding until children are at least two years of age. What is Known: • Presence of Brain-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF), and S100B neurotrophic growth factor have been shown in the breast milk of mothers whose infants are the first year of life. What is New: • Glial Cell Line-Derived Neurotrophic factors continue to present in breast milk of mothers with children aged 18, 24, and ≥ 25 months, without any significant difference in level between months.