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.