Xinxin Xing

Background: The function and bioavailability of water-soluble vitamins in human milk (HM) is contingent upon their specific molecular configurations. This study aims to investigate the concentrations of different forms of thiamine, riboflavin, and folate in HM and to elucidate the temporal variations of these nutrients across different stages of lactation. Methods: A cohort of 35 healthy mother–infant pairs from Beijing was recruited, and 214 HM samples were collected. The concentrations of water-soluble vitamins in these samples were analyzed using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). A mixed linear regression model was employed to examine the relationship between HM vitamin levels and lactation stages. Results: This study analyzed the concentrations of free thiamine, thiamine monophosphate (TMP), thiamine pyrophosphate (TPP), free riboflavin, flavin adenine dinucleotide (FAD), flavin mononucleotide (FMN), 5-methyl-tetrahydrofolate (5-MTHF), tetrahydrofolate (THF), 5-formyl-tetrahydrofolate (5-fTHF), 5,10-methenyl-tetrahydrofolate (5,10-MTHF), and unmetabolized folic acid (UMFA) at various lactation stages (0–7 days, 15 days, 30 days, 60 days, 90 days, 120 days, 150 days, and 180 days). Free thiamine concentrations increased from colostrum to 180 days, while total thiamine rose during the first month and then stabilized. Free and total riboflavin levels remained relatively constant throughout lactation. Free and total folate concentrations peaked at 90 days and subsequently declined. Significant correlations were observed between follow-up time and changes in free thiamine, free folate, and total folate concentrations over 180 days. Conclusions: This study provides detailed data on the concentrations and trends of free and total thiamine, riboflavin, and folate in HM from 0 to 180 days postpartum, highlighting the dynamic nature of vitamin concentrations in HM. No deficiencies in these HM vitamins were detected in the surveyed population. Future further research will be conducted to reveal the correlation between different forms of water-soluble vitamins in HM and dietary factors.

This study aims to explore the relationship between macrosomia and amino acids in maternal and cord sera. Methods: In the case-control study, 78 pairs of mothers and newborns were recruited from December 2016 to November 2019. Participants were divided into the macrosomia group (BW ≥ 4000 g, n = 39) and the control group (BW between 2500 g and 3999 g, n = 39) according to the birth weight (BW) of newborns. Maternal vein blood samples were collected before delivery and cord vein blood samples were collected after birth. The levels of amino acids in maternal and cord sera were measured by liquid chromatography and mass spectrometry (LC-MS/MS) in the year 2021. The difference in amino acid levels in maternal and cord sera between the two groups was compared, and the contribution of each amino acid to the difference between the two groups was analyzed. Unconditional logistic regression analysis was used to test the relationship between macrosomia and amino acids. Results: In maternal serum during the antepartum, the levels of asparagine, glutamine, methionine, alanine, and threonine in the macrosomia group were higher but arginine was lower than that in the control group (p < 0.05). In cord serum, the levels of lysine, histidine, phenylalanine, arginine, tryptophan, valine, isoleucine, glutamate, tyrosine, and total essential amino acid (EAA) in the macrosomia group were lower while glutamine was higher than that in the control group (p < 0.05). The ratios of EAA, valine, threonine, methionine, tryptophan, and alanine in maternal serum to those in cord serum were higher, while the ratio of glutamine was lower in the macrosomia group (p < 0.05). Arginine and threonine in maternal serum and glutamate, glutamine, and histidine in cord serum were associated with macrosomia (p < 0.05). Conclusion: Most of the amino acid levels in the maternal sera of the macrosomia group are higher than those in the control group, while most of the amino acids’ levels in the cord sera of the macrosomia group are lower than those in the control group. The ratios of some amino acids in maternal serum to those in cord serum were different between the two groups. Arginine and threonine in maternal serum and glutamate, glutamine, and histidine in cord serum are closely related to macrosomia.