DHA intake interacts with and genetic variants to influence polyunsaturated fatty acids in human milk.

Endogenous synthesis of PUFAs is mediated by genes controlling fatty acid elongases 2 and 5 ( and ) and by exogenous DHA intake. Associations between elongases and PUFA levels probably involve genetic variants of and changes in DHA intake, but data about their combined effect on PUFA levels are sparse. We hypothesized that each factor would directly affect PUFAs and that interactions between haplotypes and DHA intake would influence PUFAs. We explored four levels of DHA intake in pregnant Chinese Han women and 10 SNPs in the genes to determine associations with PUFAs in breast milk. The SNP rs3798713 and 3-SNP haplotype (rs2281591, rs12332786, and rs3798713) in were associated with linoleic acid (LA) concentrations. However, carriers of the 3-SNP haplotype with higher DHA intake (second quartile: 14.58-43.15 mg/day) had higher concentrations of LA, arachidonic acid, EPA, and DHA compared with the interaction baseline. In , five SNPs (rs2294867, rs9357760, rs2397142, rs209512, and rs12207094) correlated with PUFA changes. Compared with those who had the 5-SNP haplotype C-A-C-G-A and low DHA intake (<14.58 mg/day), carriers with other haplotypes (A-A-C-A-A or C-A-C-A-A) and high DHA intake (≥118.82 mg/day) had increased EPA levels after adjustments for age and BMI. This study showed that maternal genetic variants in and were associated with PUFA levels in breast milk and that the combination of SNP haplotypes and higher DHA intake increased PUFA concentrations.