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"Subsequent studies by Pawlosky et al. (2001) using similar technology and that more recently by Hussein et al. (2005) showed estimated conversions from ALA to DHA of less than 0.1% and a conversion to EPA plus DHA combined of less than 0.4% efficiency overall. The latter study was conducted over a fairly lengthy time period of 12-weeks in duration. Burgee et al. from the U.K. has compared the apparent conversion efficiency of ALA to DHA in young adult men and women. Interestingly, no detectable formation of DHA was found in the men whereas an approximate conversion efficiency from ALA to DHA of 9% was found in women. These authors suggest that the greater fractional conversion in women may be due in part to a significantly lower rate of utilization of dietary ALA for beta-oxidation and/or the influence of estrogen or other hormonal factors on the conversion efficiency. In summary, the conversion efficiency from ALA to DHA is very limited in healthy individuals; furthermore, the apparent inefficiency of the conversion from ALA to DHA is markedly variable between individuals within different sectors of the populations such that the lack of sufficient dietary DHA could compromise optimal health in those with very minimal conversion capacities. The very low conversion efficiencies and wide variation in capacities lend support to serious consideration being given to dietary DHA as an 'essential' fatty acid and/or a 'conditionally essential' fatty acid depending upon the conversion capacity of individuals within the population."
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