Hi all,

  I lost track of the discussion on ALA, GLA, etc., but I found some concise
information in one article.  Please excuse me if I'm duplicating something
already posted.

EPA, DHA, and the Omega-3 family of eicosanoids are important types of
Omega-3 fatty acids.  Normally our body can manufacture all of these
products if it has plenty of the parent Omega-3 fatty acid called
Alpha-Linolenic Acid (ALA) found naturally in green leafy vegetables, flax,
flaxseed and canola oil, walnuts and Brazil nuts.

Our bodies convert ALA to EPA; EPA to DHA; and DHA to Omega-3 Eichosanoids.
There are many things that can interfere with this process, especially
vegetable oils in the diet.  Note that it is possible to acquire EPA and DHA
directly by eating fish oil, certain eggs, or by taking supplements.  Fatty
fish contain plenty of both substances. Plenty of studies have shown that
fish-eating cultures have much better health, including mental health.

DHA is particularly important for brain functions.  Scientists have
discovered that severely depressed people are lower in DHA, and the more
depressed they are, the less DHA they have.  One ancient remedy for
depression was to feed the patient animal brains, now known to be extremely
high in DHA and Omega-3 fatty acids. Incidentally, alcohol is known to
deplete DHA stores extremely rapidly.

While the body can theoretically manufacture its own DHA out of the parent
ALA fatty acid, things can interfere with this conversion.  The most
important problem is an excess of Omega-6 fatty acids in the bloodstream,
which use the same enzymes for a similar type of conversion.  This is why it
is extremely important not to have too many Omega-6 fats in your diet (the
vegetable oils like sunflower and soybean oil).    Other problems might
inhibit the conversion process, such as a deficiency in certain vitamins and
minerals.

I hope this is of some use.

Siobhan