Supplementary Material for: Total and Sn-2 Fatty Acid Profile in Human Colostrum and Mature Breast Milk of Women Living in Inland and Coastal Areas of China

Introduction: Although lipid is the major energy source and exerts beneficial effects on infant growth, research on the composition of fatty acid (FA) at the sn-2 position of human milk (HM) in China and abroad is limited. Objectives: This study aimed to investigate the FA positional distribution in colostrum and mature HM of women living in the inland and coastal areas of China and explore the potential influences of geographical region and lactation stage on the FA profile of Chinese women. Methods: Colostrum milk (n = 61) and mature milk (n = 56) samples were obtained longitudinally from healthy lactating women in Guangzhou and Chengdu, China. Gas chromatography was used to determine the total and sn-2 FA composition. Results: Significant differences were observed in the FA profile of HM between different regions and lactation stages, with differences in polyunsaturated FA levels being the most pronounced. Nearly 70% of sn-2 FAs were saturated FAs, of which C16:0 accounted for approximately 75%. C8:0, C10:0, C18:0, C20:0, C22:0, and all of the unsaturated FAs were mainly located at the sn-1 and sn-3 positions, while C14:0, C15:0, and C16:0 were mainly at the sn-2 position. The proportion of C12:0 and C17:0 at sn-2 was approximately equivalent to that at the sn-1, 3 positions. Conclusions: The results indicate the variability in the FA profile of HM between regions and lactation stages. The contents of polyunsaturated FAs and sn-2 FAs, especially palmitic acid, should be paid more attention when optimizing infant formula.

引言：尽管脂质是婴儿的主要能量来源，且对其生长发育具有积极作用，但目前国内外针对人乳（human milk, HM）中脂肪酸（fatty acid, FA）在sn-2位的组成相关研究仍较为有限。研究目的：本研究旨在探究中国内陆与沿海地区女性初乳及成熟人乳的脂肪酸位置分布特征，并探讨地理区域与泌乳阶段对中国女性人乳脂肪酸谱的潜在影响。研究方法：本研究纵向采集了中国广州与成都两地健康泌乳女性的初乳样本（n=61）及成熟乳样本（n=56）。采用气相色谱法测定总脂肪酸及sn-2位脂肪酸的组成。研究结果：不同区域与泌乳阶段的人乳脂肪酸谱存在显著差异，其中多不饱和脂肪酸（polyunsaturated FA）水平的差异最为显著。约70%的sn-2位脂肪酸为饱和脂肪酸，其中C16:0占比约75%。C8:0、C10:0、C18:0、C20:0、C22:0及所有不饱和脂肪酸主要分布于sn-1与sn-3位，而C14:0、C15:0及C16:0则主要定位于sn-2位。sn-2位的C12:0与C17:0占比与sn-1、3位大致相当。研究结论：本研究结果表明，不同区域与泌乳阶段的人乳脂肪酸谱存在差异。在优化婴儿配方食品时，应更加关注多不饱和脂肪酸及sn-2位脂肪酸的含量，尤其是棕榈酸。