On Sun, 18 Aug 2002 08:03:16 +1000, Balzer, Ben <[log in to unmask]> wrote:

>PROBLEM is that the enzyme delta-6-desaturase D6DS which acts on LA and LNA
>early in the essential fatty acid (EFA) pathway ALSO acts later on to
>produce DHA the brain-essential fat. Thus excess amounts of either can clog
>up D6DS and block production of DHA.

Ben, where did you get from that d6d is involved later in producing DHA?
I couldn't find this, but I have two opposing references which specify that
not d6d but annother enzyme, d4d is making DHA.
In this way only LA (as a natural source) competes for d6d in unsaturating
omega-3 fatty acids. Therefore blocking w-3's.

Other factors impairing d6d listed are:
Alcohol consumption
Aging
High dietary intake of cholesterol and tatry' acid
Diabetes
Low levels of enzyme co-factors

In addition the graphic on page 20 of "Fats that Heal, Fats that kill"
d6d also works on OA (monounsaturated) and palmitic acid (saturated).
These may also compete with ALA/LNA, but probably at a lower priority.
Like d6d preferres LNA over LA by a factor of 4:1.
(Suggesting that at least 1/4 of all short chain EFAs should be LNA
to result in equal amounts of the succussors)

Annother factor and thought of mine is as follows:
Further processing in the pathways is done by D5D.
This is the one producing the dreaded AA (precursor of bad prostaglandins)
out of DGLA (precursor of good prostaglandins).
So, if some omega-3 produce competes for *d5d* this would have a very
beneficial effect.
This even more, if d5d also has a preferance to process omega-3 fats (like
d6d has).
That's a good reason to include enough of LNA, compared to LA:
The downregulation of d5d effects on DGLA, therefore downregulating AA
production, therefore positively influencing prostaglandin production.

Basically the omega-3 Prostaglandins are reported to have "weak" effects,
compared to stong effects of omega-6 prostaglandins (both bad and good).
In this way controlling d5d should be much more important as producing much
EPA and omega-3 prostaglandins.

regards

Amadeus S.
(I enjoyed your comments about Fallon's articles)