New study: Effects of n−6 PUFAs compared with SFAs
Stephan Guyenet tweeted this study recently. (If you're not following him on twitter btw you are missing out!)
I know it's only 10 weeks but doesn't that strike you as a surprising result?
Higher insulin, higher liver fat and a worse lipid profile on SFA compared to PUFA.
The weight gain difference was not significant so it couldn't be explained by the extra palatability of the butter compared to the PUFA (haven't read full text but presuming some kind of nasty product like soy-bean 'butter').
How can we place this study in the context of wider research?
Maybe reducing liver fat isn't always good...
"A diet enriched in saturated fatty acids effectively reverses alcohol-induced necrosis, inflammation, and fibrosis despite continued alcohol consumption. The therapeutic effects of saturated fatty acids may be explained, at least in part, by reduced endotoxemia and lipid peroxidation, which in turn result in decreased activation of NF-κB and reduced levels of TNF-α and Cox-2. "
"Rats in group 1 were fed a fish oil-ethanol diet for 6 weeks. Rats in groups 2, 3, and 4 were fed fish oil and ethanol for 6 weeks. Ethanol administration was stopped at this time, and the rats were switched to isocaloric diets containing dextrose with fish oil (group 2), palm oil (group 3), or medium-chain triglycerides (group 4) as the source of fat for an additional 2 weeks. Rats in groups 5 and 6 were fed fish oil-ethanol and fish oil-dextrose, respectively, for 8 weeks. The most severe inflammation and fibrosis were detected in groups 1 and 5, as were the highest levels of endotoxin, lipid peroxidation, and mRNA for Cox-2 and TNF-α."
This is an exact duplicate of this question, asked and answered in great detail one month ago: http://paleohacks.com/questions/110169/new-study-effects-of-n6-pufas-compared-with-sfas
Someone should close this as an exact duplicate. (I can't, as I'm not a moderator.)
Except that when most people here say PUFAs are good for us, they don't refer to industrial oils in large quantities, the refer to n3's via fish. Also, fatty liver (NASH) is caused by high amounts of fructose, so perhaps a period of limiting fructose is a better way to go?
This would be an interesting development if true. Anyone have access to the full study to see if the data matches the conclusion?
It's certainly conceivable that if you're eating saturated fat, your body will burn what you consume rather than taking it from fat stores - one of those being your liver's storage.
So perhaps it's a question of the lack of saturated fats that causes our bodies to burn our stored fat rather than the presence of n6 PUFAs? Just a thought. If so, we'd also expect fat loss elsewhere, not just in the liver. Perhaps the rest of the paper has this data one way or another?
I dont have the full article, but the Clinical Trial has the PUFA or SFA energy at 15%, and the PUFA as "rich in linoleic acid, omega-6." (http://clinicaltrials.gov/show/NCT01038102) Which means this is a high carb diet.
Two things to keep in mind. First, looking at just one aspect of the body misses several key points. One main reason why Paleo people like saturated fat is that PUFA is very easily oxidized, and can cause inflammation in the body. It may not show looking at one particular piece of the body, but the inflammation over a long period can cause issues.
Secondly, Paleo tends to be a lower carb, and thus lower insulin producing diet than the typical clinical or standard diet. Thus, how SFA acts within a low carb diet is different than how it acts in an environment that includes lots of carbs.