Many (I would guess ALL big names) paleoists claim that PUFAs increase inflammation and cause fatty liver. Here is proof that that is not always, if ever, the case.
A Swedish trial from 2012: http://www.ncbi.nlm.nih.gov/pubmed/22492369
Note that subjects were overweight but I don't see why that will nollify the findings of the study.
Best article - bar none - I have ever read on the PUFA debate is here:
The biochemists argue the Omega-6 oils are very inflammatory and point to research by William Lands showing that there is a strong cross-cultural correlation between levels of Omega-6 in body tissue and risk of death.
The clinicians don't apparently have time for any science, and simply point to empirical studies where Omega-6 lowers cholesterol and other specific risks.
What people need to understand is that in order to really study this issue correctly, you would need to design a study where people ate 2%, 4%, 6%, etc of total calories from Omega-6 PUFA. The food chain is so completely messed up that most people in the US are getting 9%+ in Omega-6, and the study is effectively impossible to do. You would have to prepare all meals for people for a full decade. The study would cost a fortune and no one has any monetary incentive to do that research.
My own opinion is that humans only need small trace amounts of Omega-6 *and* Omega-3, and if you can manage to develop a diet with low Omega-6, this lowers your need for Omega-3 to combat the negative effects of the Omega-6. I personally find the arguments presented by the biochemists to be clear and compelling and based on real science. I personally find the research done by the American Heart Association and other clinician groups to be ad hoc and not convincing because in almost all cases they increase Omega-3 at the same time they increase Omega-6. The groups who back that research usually have conflicted commercial interests with industrial seed farmers.
This is a very contentious area of research and if you get four researchers in a room you will probably get four totally different opinions.
The article you cite is linked to this literature survey, which summarizes many o-3 vs o-6 vs sat fat studies, and is published in full free text.
These studies are generally conducted on obese individuals, and the results are conflicting but generally show low grade inflammatory responses to both PUFA and saturated fats, and slight anti inflammatory responses to o-3 (though one study points out that it takes 125-250g of oily fish to see a benefit, or about 1-2 cans of sardines a day).
So there is a slight, but measurable, effect from any of these fats on obese subjects. At the very least the pundits are making a mountain out of a molehill regarding inflammation.
For non-obese individuals there is probably less effect. Not even a molehill's worth. But that never stops a good blog artist.
So the question remains: how big a deal really are PUFA's, especially n6? I've been relaxing a bit lately on this (usually pretty obsessive).
Incidentally I notice some acne and what 'feels' like mild gut inflammation since I've let just a bit more n6 in (mostly from egg yolks, chicken, and the odd almond here and there) and backed off the oily fish a little...
Not that correlation = causation or that my 'gut feeling' of gut inflammation is even real... The acne and skin irritation certainly are, but could be attributed to something I'm not taking into consideration.
Um, fish oil is PUFA - n3 PUFA and it lowers inflammation. So no. n6 PUFA can cause inflammation if you consume far more n6 over n3. Try to get near a 1:1 ratio, and most importantly avoid oxidized PUFAs. This is why fish oil stinks so bad - to warn us not to eat it.
The same is true of n6 PUFAs except that industrial "vegetable" or seed oils have been degummed, deoxidized, so we can't smell them.
Both n6 and n3 are "essential" - we need small amounts of both - not insanely high amounts. Try to get most of your fats from MUFA, SFA, and MCT, and a bit of n3 and n6 PUFA. Good sources of n6 PUFA would be duck or chicken fat.
"Does PUFA create fatty liver and inflammation as many paleoists claim?"
I do not know about the inflammation bit and to which 'paleoists' you are referring to, but there are few studies linked here, which tend to show the opposite, ie. that excess unsaturated fats tend to end up in the butt & thigh areas (not around the liver) and excess saturated fats tend to end up in the abdominal area.
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