Estrogen increases the conversion of α‐linolenic acid to docosahexaenoic acid in ovariectomized mice

Abstract

n‐3 polyunsaturated fatty acids (PUFA), namely eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have beneficial health effects. The conversion of α‐linolenic acid (ALA) to EPA and DHA is low, especially in males compared to females and varies in the literature. Estrogen (E2) is suggested to affect ALA conversion but few studies have confirmed the E2 effect. Our objective was to determine the independent effect of E2 on n‐3 PUFA levels in serum and various tissues in female ovariectomized mice fed diets with low and high ALA. After 7 weeks exposure to an E2 pellet, mice were randomized to a corn oil‐based basal diet or an ALA‐rich flaxseed diet (FS) with or without removal of the E2 pellet for 4 weeks. E2 responsiveness was indicated by the 269% higher (P<0.001) uterus weight in E2‐ treated mice compared to those with E2 pellet removed. FS‐fed mice had higher proportions of ALA, EPA and DHA in total lipids extracted from serum, liver and brain. E2‐treated mice had higher serum (15.1%; P<0.001) and liver (18.2%; P<0.001) DHA but not brain DHA. EPA levels were not affected by E2. There was a diet × E2 interaction for ALA in the liver where the FS+E2 group had lower ALA compared to FS‐E2. In conclusion, E2 results in higher serum and liver DHA, does not affect brain DHA and does not affect EPA in any of the tissues measured. This finding may help explain the variability in ALA effect in studies involving males and females.Grant Funding Source: NSERC