Key Findings:
Much controversy exists regarding the conversion of ALA to longer chain omega 3 fatty acids. Most of this data has been collected using male subjects. The data here supports numerous papers that report dietary ALA conversion to EPA. The findings are among the first to show that women convert ALA to EPA much more effectively than men. The conversion to EPA is most likely due to the effects of female sex hormones in regulating the endogenous synthesis of longer chain omega 3 fatty acids. The authors conclude that women who are unable or choice not to consume fish would benefit from ALA rich diets, and that the data provide evidence for an alternative and sustainable dietary source of omega 3 fatty acids.
ABSTRACT:
There is a metabolic pathway by which mammals can convert the omega-3 (n-3) essential fatty acid alpha-linolenic acid (ALA) into longer-chain n-3 polyunsaturated fatty acids (LC n-3 PUFA) including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). As far as we know there are currently no studies that have specifically examined sex differences in the LC n-3 PUFA response to increased dietary ALA intake in humans, although acute studies with isotope-labelled ALA identified that women have a significantly greater capacity to synthesise EPA and DHA from ALA compared to men. Available data from a placebo-controlled, randomised study were re-examined to identify whether there are sex differences in the LC n-3 PUFA response to increased dietary ALA intake in humans. There was a significant difference between sexes in the response to increased dietary ALA, with women having a significantly greater increase in the EPA content of plasma phospholipids (mean +2.0% of total fatty acids) after six months of an ALA-rich diet compared to men (mean +0.7%, P = 0.039). Age and BMI were identified as predictors of response to dietary ALA among women.
CONCLUSIONS:
Women show a greater increase in circulating EPA than men during increased dietary ALA consumption. Further understanding of individual variation in the response to dietary ALA could inform nutrition advice, with recommendations being specifically tailored according to habitual diet, sex, age and BMI.
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