Macro partitioning
Increasing dietary intake of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) down-regulates the metabolic conversion of alpha-linolenic acid (ALNA) to longer-chain metabolites (EPA and DPA) in older men, whereas increasing ALNA intake does not up-regulate this conversion.
If you are trying to increase your long-chain omega-3s (EPA/DHA) by eating more plant-based sources (like flax or walnuts), understand that your body's conversion rate is very low and fixed. Increasing your intake of these plant fats will not significantly boost your EPA/DHA levels because your body does not up-regulate the conversion process. To effectively raise EPA/DHA, you must consume pre-formed sources (fatty fish or supplements), which may actually further suppress any minimal conversion from plant sources.
The present results indicate ALNA conversion was down-regulated by increased product (EPAþDHA) availability, but was not up-regulated by increased substrate (ALNA) consumption.
Why this rating
Small sample size (n=14 total, split into 3 groups) and short duration (8 weeks), though using rigorous tracer methodology.
Source
Effect of altered dietary<i>n</i>-3 fatty acid intake upon plasma lipid fatty acid composition, conversion of [<sup>13</sup>C]α-linolenic acid to longer-chain fatty acids and partitioning towards β-oxidation in older men
Graham C. Burdge et al. · British Journal Of Nutrition · 2003
DOI 10.1079/bjn2003901
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