Human milk fatty acid composition is associated with dietary, genetic, sociodemographic, and environmental factors in the CHILD Cohort Study

Abstract

Background Fatty acids are a vital component of human milk. They influence infant neurodevelopment and immune function, and they provide ∼50% of milk's energy content. Objectives The objectives of this study were to characterize the composition of human milk fatty acids in a large Canadian birth cohort and identify factors influencing their variability. Methods In a subset of the CHILD cohort (n = 1094), we analyzed milk fatty acids at 3–4 mo postpartum using GLC. Individual and total SFAs, MUFAs, and n–3 and n–6 PUFAs were analyzed using SD scores and principal component analysis (PCA). Maternal diet, sociodemographic, health, and environmental factors were self-reported. Single-nucleotide polymorphisms were assessed in the fatty acid desaturase 1 (FADS1-rs174556) and 2 (FADS2-rs174575) genes. Results Fatty acid profiles were variable, with individual fatty acid proportions varying from 2- to >30-fold between women. Using PCA, we identified 4 milk fatty acid patterns: “MUFA and low SFA,” “high n–6 PUFA,” “high n–3 PUFA,” and “high medium-chain fatty acids.” In multivariable-adjusted analyses, fish oil supplementation and fatty cold water fish intake were positively associated with DHA and the “high n–3 PUFA” pattern. Mothers carrying the minor allele of FADS1-rs174556 had lower proportions of arachidonic acid (ARA; 20:4n–6). Independent of selected dietary variables and genetic variants, Asian ethnicity was associated with higher linoleic acid (18:2n–6) and total n–3 PUFAs. Ethnic differences in ARA were explained by FADS1 genotype. Maternal obesity was independently associated with higher total SFAs, the “high medium-chain fatty acid” pattern, and lower total MUFAs. Lactation stage, season, study site, and maternal education were also independently associated with some milk fatty acids. No associations were observed for maternal age, parity, delivery mode, or infant sex. Conclusions This study provides unique insights about the “normal” variation in the composition of human milk fatty acids and the contributing dietary, genetic, sociodemographic, health, and environmental factors. Further research is required to assess implications for infant health.

Genetic and Physiological Factors Affecting Human Milk Production and Composition

“…These findings were later supported by other studies that found that SNPs in the FADS gene cluster influence polyunsaturated fatty acid (PUFA) concentrations in human milk [106][107][108]. Together with a recently published study that found that mothers carrying the minor allele of FADS1 rs174556 had lower proportions of ARA [108], this finding strongly indicated that genetic variations affect human milk composition. Additionally, genetic variations in FADS and elongase (ELOVL) enzymes were shown to affect long chain PUFA (LC-PUFA) levels in human colostrum.…”

“…This lower proportion could not be compensated for by dietary fish consumption [23]. These findings were later supported by other studies that found that SNPs in the FADS gene cluster influence polyunsaturated fatty acid (PUFA) concentrations in human milk [106][107][108]. Together with a recently published study that found that mothers carrying the minor allele of FADS1 rs174556 had lower proportions of ARA [108], this finding strongly indicated that genetic variations affect human milk composition.…”

Changes in human milk fatty acid composition and maternal lifestyle-related factors over a decade: a comparison between the two Ulm Birth Cohort Studies

“…In light of this, variations in human milk fatty acid composition between individuals and populations have been attributed to cultural differences (such as diet and other lifestyle factors) (6)(7)(8)(9)(10) (11) and human genetic differences (12,13) amongst others. Human milk fatty acid composition can therefore reflect both dietary sources and endogenous biological synthesis of fatty acids (14)(15)(16)(17) .…”

Lipidome analysis of milk composition in humans, monkeys, bovids, and pigs

“…Maternal parity was also associated with differential fatty acid content in bovids and humans, favoring primiparous mothers [26,27]. Another factor that can influence milk composition, as well as the milk yield, is genetic background and variation in the genes associated with fatty acid biosynthesis [28][29][30].…”