Posted by Larry Hoover on January 21, 2007, at 9:38:59
In reply to Is DHA necessary?, posted by saturn on January 17, 2007, at 9:34:06
> I have read that DHA is just a 2-step conversion from EPA, and moreover that a high EPA/DHA ratio is best for treating ADHD, mood disorders, etc...
That "just a 2-step conversion" is really a major hurdle. The efficiency of that conversion is really quite low. It was once believed that plant sources of omega-3 (as alpha-linolenic acid) were sufficient to provide for EPA and DHA requirements, leading to the designation of alpha-linolenic as an essential fatty acid.....but, actual tests showed that DHA yield from labelled alpha-linolenic varied from 0-7%. The real bottle-neck in that conversion was found to be conversion of EPA to DHA. Recent literature has designated DHA as conditionally essential, but the trend is towards fully essential. I lean towards the latter. Getting it pre-formed makes the argument moot, non?
> So would it be sufficient to simply take 100% EPA in order to achieve the mental and cardiovascular benefits of omega 3's?
One of the confounders in understanding what happens is that EPA has an immediate effect (via eicosanoids, which are regulatory or signalling molecules), whereas DHA has long-term influences on the structure and function of membranes. I'm not surprised that DHA effects are not significant over six-week trials, or the like.
> Would you have plenty of EPA and your body would simply synthesize from this the necessary DHA?
If you're lucky.
> Thanks.
Welcome.
Lar
poster:Larry Hoover
thread:723138
URL: http://www.dr-bob.org/babble/alter/20070114/msgs/724743.html