Sunday, August 19, 2012

I am the OMEGA

I'm lying LOL I'm not really God.

"Why should I restrict my omega-6 intake? Aren't they essential fatty acids?"

Good questions! Where do you get all these great questions from?

Two reasons:

tl;dr omega-6s are converted into pro-inflammatory hormones and omega-3s are converted into anti-inflammatory hormones - one of the omega-6s, linoleic acid (18:2 ω-6), also inhibits the critical step in converting the omega-3 we get from plants, α-linolenic acid (18:3 ω-3), into the useful omega-3s, eicosapentaenoic acid (20:5 ω-3) and docosahexaenoic acid (22:6 ω-3).

Eicosanoid production

Eicosanoids and nonclassical eicosanoids are short-range hormones and neurotransmitters derived from the omega-3 and omega-6 polyunsatured essential fatty acids (be a bit wary of those wikipedia articles though since they are written by eicosanoid experts who probably have an interest in as many diseases as possible being implicated in eicosanoid signalling). Now the word 'essential' is a bit of a misnomer. Essential means that something is required in our diet because we've lost the ability to synthesize it ourselves. But the reason we've lost the ability to synthesize it ourselves is because that essential nutrient is plentiful in our diet - or at least has been plentiful in the last millions of years.
Anyway, to get back to the subject at hand, eicosanoids are fat soluble hormones and neurotransmitters of short range which means they are good for localized actions like injury. Say you cut yourself with a dirty, rusty blade. That gives you pain, blood coagulation, increased blood flow through vasodilation, swelling, mobilization of immune systems, fight of infection, and then later tissue repair, reduction of swelling and pain, shutdown of immune systems, and finally vasoconstriction so the red mark disappears and you are left with normal looking skin. These are all good things. They are part of the healing process. And eicosanoid signalling is involved in all those steps.
Now, the signalling molecules derived from the different essential fatty acids have similar themes:
Omega-6s are generally involved in up-regulating inflammatory responses (the first bit of your stab wound) and omega-3s are generally less inflamming, anti-inflammation, or resolving inflammation (the second part of your stab wound).
Both parts are needed to be healthy but neither of them should be overdone. There's a number of drugs that interact with this signalling system. Aspirin is probably the most common drug in the world and it throws a spanner in the works right at the beginning at the eicosanoid production so it reduces pain and inflammation but also decreases blood clotting making things like bleeding ulcers a greater risk.
What happens though is that industrial man eats too many omega-6 fatty acids and sometimes too few omega-3s. Which diseases are associated with increased signalling from omega-6 derived eicosanoids? Auto-immune diseases, gastrointestinal inflammatory disease, arthritis, asthma, atherosclerosis (which is why aspirin works against cardiovascular disease), allergies. In addition it could easily be involved in type-1 diabetes since that is an autoimmune disease for which the number afflicted is rising. Not to mention that endocannabinoids are synthesized from an omega-6 fatty acid and endocannabinoids increase appetite - you don't want to be fat, now do you? Or even worse, hungry.

Polyunsaturated fatty acid interconversion

While humans like other mammals aren't able to make these essential fatty acids on our own we can luckily convert the various forms (cats though can't go from the linolenic / linoleic acid to the EPA / AA which makes them obligate carnivores).
So at the top are the two common plant sources of omega-3 and omega-6 fatty acids, ALA and LA. These can then be elongated and desaturated to fatty acids that are more important in animals. Cleverly, since they are quite similar only one enzyme is needed per two kinds of fatty acids. This however also means that the fatty acids compete for the enzymes needed so if there's a lot of LA only little ALA will be turned into SDA by Δ6 desaturase. Bummer. The ALA to SDA conversion is supposed to be quite poor in humans but I'm not sure if that's when measuring on humans with a reasonable intake of LA.
In addition to the eicosanoid system polyunsaturated fatty acids are important to the composition of cell membranes (the "skin" of a cell) and in particular DHA is important for the membranes of neurons.

"Okay, if omega-3s are anti-inflammatory can't I just eat a shit-load of fish oil and not care about any of this fucking science-stuff?"

Well, you can eat anything you want but if you want to be healthy then you need to consider whether there's too much omega-6 in your diet.
Omega-3 derived eicosanoids aren't directly antagonistic to omega-6 derived eicosanoids but actually more cooperative. One instigates and the other cleans up. And some omega-3 derived eicosanoids are actually pro-inflammatory. Fucked, isn't it?

So let's have a look at where we find omega-6s and respectively ALA and EPA/DHA.

Omega-6 sources ranked by concentration:

1) Plant seeds (concentrated in seed oils of course). Plant seed examples are: grains, beans, peas, corn, rice, nuts, quinoa, sorghum, buckwheat (disclaimer: some nuts are actually low in omega-6 and others like rice have almost no fat). Yes, this includes flax seed, sunflower seeds (very high LA actually), sesame seeds, etc. If you've read my blog you know that I love sesame seeds and sprinkle them on lots of stuff. I don't make sesame bread though. Or any other kind of "paleo" non-grain bread.
2) Animal fat from animals raised on plant seeds. If it doesn't say grass-fed, pastured, organic (what are the feeding rules for organic meat?), or wild on the package then the animal feed will have had a very large seed component.
3) Generally in plants and animals. You are unlikely to become deficient unless you eat a very monotonous, very low fat diet. If you are really really worried that you aren't getting enough LA then eat some olives / olive oil, walnuts, and almonds. There. That won't be enough to hurt you.

EPA/DHA sources ranked by concentration: 

1) Eyes. Okay, I don't think there's much fat in an eyeball but there are buttloads of DHA in eyes - highest in the retina where it's 20-25%.
2) Braaaaaaaaaaaains. 5-10% DHA in mammalian brains.
3) Fish / fish eggs.
4) Algae, poultry, eggs, dairy. Not preferred sources in my opinion but there's a little bit there. Not much in the animal sources though and like the eyes and brains you aren't going to be eating much algae.

ALA sources ranked by concentration: 

1) Leafy greens. Specifically the green photosynthetic organelles contain heaps of ALA.
2) Some plant seeds (that are also high in LA) like flax, chia, kiwi seeds, etc are very high in ALA. Some legumes like rapeseed and soy also has fairly high ALA content but it is usually processed away because it reduces shelf life.
3) Meat and dairy from grass-fed animals. The ALA from the grass ends up in the animal. And double up on bonus because that also means that the animal ate fewer plant seeds and thus has lower LA.

See a pattern? What diet is high on seeds and low on leafy greens, fish, and braaaains? And what diet is low on seeds and high on leafy greens and grassfed beef? (Yeah, I don't want brains either)

If you answered "Industrial diet bad, paleo diet good" then I salute you for reading to the end of this ridiculously long post!

PS I never had any problems with autoimmune issues but I was raised low fat and ate even lower than the rest of my family since I don't like cheese. I figure the low fat upbringing is probably the cause of my autistic traits (autism is a very serious disease and I'm not making light of it but just pointing out that on a autism spectrum scale I would probably have been placed on the NVLD end, instead of out in the sun playing with the other kids).
PPS Mom, I totally don't blame you for the lack of fat in my childhood and I respect acknowledge that you don't want to eat paleo (that bread and cheese addiction that the world seems to have is good fuel for a blog post however) but please only buy organic dairy (especially butter, cheese, and cream but then you may as well buy the rest organic) and only use butter / ghee or coconut oil for frying and cooking and save the olive and coldpressed rapeseed oil for dressings. Oh, and for Christ sake either make ice cream yourself or buy something that's actually made from dairy. 

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