Dynamic changes at high-protein dietary pattern of major fatty acids in healthy lactating women: A systematic review and meta-analysis.

BACKGROUND: Fatty acids (FAs) in human milk are important nutrients for infants. They play important roles in energy supply, nervous system development, and metabolic function maintenance. However, how the composition of major milk FAs change with lactation stages remains controversial. OBJECTIVES: To systematically review the concentration range of major FAs in human milk at various lactation stages. METHODS: A total of 12 papers involving 50 sets of data with 3507 participants were reviewed according to the PRISMA checklist and flow diagram. The inclusion criteria was the literatures had the FAs contents in breast milk of healthy lactation mothers at three lactation stages and the dietary patterns could be calculated. The exclusion criteria were: the studies were duplicates, were unrelated to dietary patterns or breast milk composition, and/or the study populations were unhealthy. We searched PubMed, the China National Knowledge Infrastructure, WanFang, and Web of science. Agency for Health Care Research and Quality (AHRQ) was used to assess the bias of studies. The mean values of polyunsaturated fatty acids (PUFAs) including docosahexaenoic acid (DHA), arachidonic acid (AA), eicosapentaenoic acid (EPA), α-linolenic acid (ALA), linoleic acid (LA), monounsaturated fatty acids (MUFAs), and saturated fatty acids (SFAs, including lauric acid and palmitic acid), in human milk at three lactation stages (colostrum 1-7 d, transitional milk 8-14 d, mature milk 15 d-3 mo) of healthy lactating women were investigated in terms of the high protein dietary pattern. Publication biases were evaluated by Egger's test. RESULTS: According to the percentage in total fat of colostrum, transitional milk, and mature milk (% wt/wt), respectively, the results showed that PUFA (25.72%, 24.92%, and 22.69%), AA (0.85%, 0.76%, and 0.59%), DHA (0.53%, 0.47%, and 0.39%), EPA (0.15%, 0.10%, and 0.10%), and MUFA (37.39%, 37.21%, and 36.14%) contents in breast milk decreased with lactation, while another two PUFA forms, LA (17.47%, 17.82%, and 17.48%), and ALA (1.09%, 1.39%, and 1.24%) arrived at a peak in the transitional milk and then decreased in the mature milk, SFA (37.46%, 38.64%, and 40.52%), and lauric acid contents (2.78%, 4.91%, and 4.97%) increased with the lactation stages. CONCLUSION: These findings could shed light on the dynamic change progress of major FA metabolism, potentially enhancing the knowledge of lactation biology, and improving infant feeding practices to meet their needs.

Effect of Different Dietary Patterns on Macronutrient Composition in Human Breast Milk: A Systematic Review and Meta-Analysis.

The aim of this meta-analysis was to systematically review the relationships between lactation diet and the composition of mature breast milk through screening multiple databases and gray literatures, with priority given to quantitative articles published in Chinese and English. We identified 27 cross-sectional studies that included 4355 lactating women. According to these data, dietary patterns were categorized into four patterns based on the fat and protein energy supplying ratio, including rational-fat and rational-protein dietary (RR), high-fat and high-protein dietary (HH), rational-fat and high-protein dietary (RH), and high-fat and rational-protein dietary (HR). The results showed the fat content in mature milk was increased with increments of fat intake, while both the protein and lactose contents in mature milk did not increase with their intakes for lactating mothers. Among these four dietary patterns, the energy ratio of macronutrients in human milk at the RR was the closest to the estimated energy ratio for infants aged 0-6 M. In conclusion, our study represents that the rational dietary pattern should be advocated, and the irrational dietary patterns, especially high-fat and high-protein dietary patterns, should be avoided during lactation stage.