Is DHA synthesis from ALA sufficient to supply the adult brain?

Publication date: Available online 25 April 2015 Source:Progress in Lipid Research Author(s): Anthony F. Domenichiello , Alex P. Kitson , Richard P. Bazinet Docosahexaenoic acid (DHA) is important for brain function, and can be obtained directly from the diet or synthesized in the body from α-linolenic acid (ALA). Several studies have estimated DHA synthesis from ALA in humans using oral administration of stable isotope ALA and concluded that it is an inefficient process with typical estimates of conversion being less than 1% of the administered dose. However, the primary fate of orally administered ALA, that is not β-oxidized, is long-term adipose storage, which would not be available for conversion over the duration of most studies. This suggests that previous measures of DHA synthesis in humans may be underestimates. Recently, the DHA requirement of the brain has been estimated to be between 2.1 and 3.8 mg daily; suggesting that even a low DHA synthesis rate may be sufficient to maintain brain DHA levels. Moreover, using a novel steady-state labeled-ALA infusion technique that is unaffected by adipose storage of tracer, the DHA synthesis rate in rats was determined to be at least 3-fold greater than the brain DHA uptake rate. This review presents evidence that ALA-derived DHA may be sufficient to maintain brain DHA homeostasis and evaluates techniques used to measure DHA synthesis.
Source: Progress in Lipid Research - Category: Lipidology Source Type: research