Hi determined, I don't have any links handy. This material I have been studying since 1989, and was linked to a medical practitioner who was researching this for a decade, although my involvement was 1993 to 1994. Books have been written about this, but I am not happy with any of them. This is a long story and I might post it in parts. Maybe I should then turn it into a blog - I get asked these questions several times a year.
Evening primrose oil supplies a fat called gamma linolenic acid, or GLA. Normally the linoleic acid, the shortest omega-6 fat, is converted to GLA by an enzyme called delta-6-desaturase, or d6d for short. It is then converted to DGLA by an enzyme called elongase. (The suffix -ase indicates an enzyme.) At this point some is diverted to make a class of hormones called series one prostaglandins, which are typically anti-inflammatory.
The DGLA can go on to be converted to arachidonic acid, which is done by delta-5-desaturase, d5d. This fatty acid is stored in cells until needed, or at least that is what is supposed to happen.
When the arachidonic acid is released it causes two things. It creates a class of hormones called eicosanoids. One group of these hormones is the series two prostaglandins, others are immune stimulators, typically inflammatory. The immune stimulators are useful for fighting off infection, while the prostaglandins are essential for life (as are the series one prostaglandins, which are also eicosanoids though from a slightly different synthesis path).
The other thing arachidonic acid can do, if released into the cell near mitochondria, is create a massive oxidative burst - last I researched this the cause was unknown.
Why the arachidonic acid is over-used in ME and CFS is a story for another post, as is the oxidative stress issue. For this post I will discuss salicylates.
The enzymes d6d and d5d are inhibited by alcohol and oxidative stress. The strongest marker for low activity is low levels of reduced glutathione. Since ME and CFS are oxidative stress disorders we are prone to this. It means we cannot synthesize enough arachidonic acid, and many of us are deficient in it. Certain organ meats and other animal products contain a lot of arachidonic acid, but I will discuss that in another post - its ties in with over-utilization.
Since we lack arachidonic acid (not all of us, not all the time, but typically) we are deficient in hormones essential for good health and immunity.
Salicylates also target d5d and d6d, this was discovered in Australia in 1984. I hope to post references in a future post, I just wanted to get the facts out there initially. Since they target these enzymes, they decrease eicosanoid synthesis. So when you ingest salicylates, you are inhibiting enzymes needed to make many essential hormones, the eicosanoids. Eicosanoids typically last seconds to minutes - you need to keep making them. Sometimes you can react badly to salicylates, sometimes less so, if you have little arachidonic acid and poor synthesis to start with. This explains the variable nature of salicylate sensitivity. It is also dose dependent - a little salicylate does a little harm, a lot does a lot of harm if you are vulnerable.
Now salicylates are in most plant foods. Quantity varies, some spices for example are very high in salicylates. Aspirin is a synthetic salicylate, and it actually destroys the enzyme needed to process arachidonic acid into hormones (cyclooxygenase, see
http://en.wikipedia.org/wiki/Cyclooxygenase ). Other NSAIDs target this same molecule, but use a different mechanism. Cortisol prevents arachidonic acid being released from membranes to be used to make hormones, which is why it is anti-inflammatory.
Traditional therapy for salicylate intolerance aims at avoidance in diet - exclusion diets. I don't agree with this, but that is again for another post.
Evening primrose oil thus contains a precursor to two classes of eicosanoids. The series 1 prostaglandins are anti-inflammatory, and if these are what is primarily made you will feel better. The problem occurs if the fats go down the other pathway.
There is another branch of eicosanoids made from omega-3 fats, and these include the series 3 prostaglandins. This is one of several reasons why fish oil is good for us usually.
Bye
Alex
