Associations among FADS1/2 expression, long-chain polyunsaturated fatty acid metabolism, and adipokines in colostrum and mature human milk.

Long-chain polyunsaturated fatty acids (LC-PUFAs) and adipokines in human milk are important contributors to early metabolic programming. This study examined fatty acid desaturase (FADS)1/2 expression, LC-PUFA profiles, desaturase activity indices, and leptin/adiponectin concentrations across lactation stages in Egyptian mothers. Total PUFA levels were higher in mature milk than in colostrum (n-3: 2.16 ± 0.74% vs. 1.29 ± 0.44%; n-6: 22.17 ± 6.49% vs. 16.41 ± 4.37%), together with increased Δ6-desaturase and n-3 pathway indices, whereas FADS1/2 mRNA expression remained unchanged between lactation stages. Leptin and adiponectin concentrations decreased by approximately 13% and 10%, respectively, and were inversely associated with LC-PUFAs, including arachidonic acid (AA) and docosahexaenoic acid (DHA), as well as desaturase indices. In contrast, leptin showed positive correlations with saturated fatty acids (SFAs) and monounsaturated fatty acids (MUFAs). FADS1/2 expression was primarily associated with n-6 fatty acid products, particularly gamma-linolenic acid and AA, and these patterns were consistent with a possible role of substrate availability. These findings highlight potential associations among FADS gene expression, PUFA metabolism, and adipokine composition in human milk, and suggest that maternal dietary intake of α-linolenic acid (ALA) and linoleic acid (LA) may contribute to LC-PUFA availability for the infant.