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I guess what I really mean to ask is, are there any underlying causes or mechanisms that would influence whether or not omega-6's become incorporated into cellular membranes, vs. just being burned up by the body? Can some people eat more omega 6 without it becoming concentrated in their tissues? We know that high tissue omega 6 is a pretty good indicator for many diseases, but is there specific evidence of how the diet translates to tissue concentrations? And should omega 6s from nuts, avocados, meats etc really be lumped together with omega 6s from refined vegetable oils?

How is it that some people can so adamantly declare keeping PUFA under 4% of calories, yet mainstream advice is to eat plenty of PUFA? How can they be so opposite side of the spectrum from one another??

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 Great question. If the body has an optimal o3:o6 ratio, will it regulate how much dietary omega-6 is absorbed into cellular membranes? I've always wondered this. – Phoenix Mar 20 2011 at 22:28
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 Those are all very good questions! The manner in which different omega 6's are burned vs stored vs used for membranes vs whatever has not been talked about much. Maybe somebody can chip in some information about GLA and other omega 6's, with regards to these questions? – Kamal♦ Mar 20 2011 at 23:07
Really interesting question--hope someone can shed some light on this. – losterman Mar 20 2011 at 23:23
Certain substances, like CLA, fish oil or NSAIDS, can inhibit the production of LA-derived eicosanoids. I don't know what happens to that LA though. The other two fates of dietary LA are metabolism and incorporation into membranes. I don't know what factors affect these processes... – Jay Mar 21 2011 at 0:04
Because there are different kinds of PUFA/MUFA/Sat Fat, which all seem subtle differences in effects but are relatively unstudied, I don't think this is an area that anybody knows much about. Answering properly is probably years away. – Turnkey Mar 21 2011 at 4:59

2 Answers

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http://www.genome.jp/kegg/pathway/map/map00591.html

http://www.ncbi.nlm.nih.gov/pubmed/20920595

Lipids get incorporated equally based upon their concentration gradients. Older humans studues put the ideal ratio 3-5 to 1 omega 6/3.......so they key is to get tested and reverse it. I think this is the one test that shocks more of my own patients. They can not believe how much omega 6 they have in their cell membranes.

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Mainstream advice is also to eat a very lowfat diet and to eat lots of carbs. You are welcome to keep your carbs at 300g a day and your fats at less than 10% (and most of that PUFA instead of SFA) if you'd like.

All I can offer you is anecdotal evidence, short of sitting here raiding Science Daily articles and searching all over Google like you could be doing instead. (sorry for the snark) But I've done the lots and lots of carbs a day thing, and while I probably didn't get my fats under 10 percent (I don't think I have ever consciously attempted to follow a lowfat diet), I can say with some authority that most of my FAs were PUFAs and hydrogenated fats because I ate margarine and a lot of industrial prepackaged foods.

Bottom line: I felt like crap. And probably did some damage I can never, ever repair.

Self-experiment. You sound reluctant to take people's word for it, so feel free to experiment and find out for yourself. At the end of the day, basing one's dietary practices on research studies is playing the odds. There's no need to do that. What's important is how a dietary regime makes YOU feel and how it makes your labs turn out.

I'm going to go right ahead and predict that what makes you feel good is not terribly far off from what makes most human beings feel good--as in genuinely healthy, not high on fat deprivation or sugar overdose--but the only way you will find out is to try.

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How does this answer any of Daniel's questions? He is obviously not asking if SAD would make him feel better than paleo. There has been sporadic talk about his questions, with regards to some tribes eating loads of nuts, arachidonic acid in meat as opposed to plants, etc. I would hope paleohacks would be a place that people could ask questions about hacking the paleo diet. – Kamal♦ Mar 20 2011 at 23:04
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 "You are welcome to keep your carbs at 300g a day and your fats at less than 10%" That's a rather crass and presumptuous reply, insulting even. I was trying to ask a serious question, one that is not only a major tenet of paleo eating, but one of the largest dividing lines between us and both CW/SAD. How can you ever persuade someone on the benefits of paleo when their doctor is telling them to load up on flax and canola? These issues must be brought out into the light and confronted. – Daniel Mar 21 2011 at 0:36
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 Eating tons of margarine and processed food? Of course you felt terrible! But someone tells me eating an avocado and 2 oz of almonds a day, bring my PUFA intake to 6-7% and suddenly I'm doomed? And how about Dr William Davis of Heart Scan Blog, touting alpha linolenic acid as a life saver? – Daniel Mar 21 2011 at 0:37
Daniel- all good points. What irks me a bit is that Dana's reply can essentially be used to answer most questions on paleohacks. Q: "How much is too much fructose" A: "You can foolishly read up on the science, but self experimentation will show you that a paleo diet is best. When I ate a crappy diet, I felt bad." Q: "Is too much coffee bad for you" A: "You can foolishly read up on the science, but self experimentation will show you that a paleo diet is best. When I ate a crappy diet, I felt bad." – Kamal♦ Mar 21 2011 at 4:28
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 Uncalled for rudeness. We all have our days, though. – Carlos Mar 21 2011 at 19:36
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