What are the proven negative effects of linoleic acid consumption? A common theme seems to be that it is converted into arachidonic acid that increases inflammation. Yet most people seem happy to consume large amounts of arachidonic acid itself in meat, eggs and organ meat?
It seems a lot like the way saturated fat was demonised years ago on quite circumstantial and inconclusive evidence. I understand about 3:6 ratios but that is as much about increasing 3 than reducing 6 to nothing. I also understand that linolenic acid intake is very high now but do not see the reason to reduce it to close to zero.
By the way I am not refering to use of sunflower oil or corn oil etc, just good foods like nuts, chicken, pork, olive oil etc.
Why do people seem to be treating linoleic acid (omega 6) and overall polyunsaturated fat intake as so bad?
In my opinion, the best reason for being suspicious of excessive consumption of linoleic acid (LA) is that it is unnatural. There is decent epidemiological data showing that people that eat very low LA diets do very well.
The most common mechanistic argument is that excessive LA leads to excessive arachidonic acid (ARA), which is a precursor for inflammatory eicosanoids. That theory is losing support as new studies don't support it. For example, see this recent study. And, here's another recent study showing that LA leads to less, not more, ARA. Also, ARA derived eicosanoids are necessary for healing and mucosal defense (both of which reduce inflammation long-term) and at least one ARA derived family of eicosanoids are anti-inflammatory mediators -- the lipoxins. Maybe this is why eggs have never been shown to be bad, despite their high ARA content.
Another mechanistic argument against excessive consumption of LA is that it depletes the body of antioxidants and the resulting oxidative damage produces disease.
On the other hand, there are mechanistic arguments that support consumption of LA. LA lowers LDL cholesterol for example. LA may also crowd out longer chain PUFAs from cell membranes, leading to membranes that are more resistant to oxidation, potentially leading to increased lifespan...
Although we may not know why yet, I think excessive consumption of LA is very likely bad. It may be that eicosanoid biology is not as simple as many assumed and the proper balance, whatever it is supposed to be, is thrown off by excessive consumption of LA. Or, LA may be bad for entirely other reasons.
Stephan has a posting from last Friday about LA and evidence that LA appears to cause generational obesity in mice after only three generations.
Dr Harris is definitely anti-linoleic acid....as is Dr Eades.
I think I'll stick with good old saturated fat in my beef, my coconut oil, my butter, my salmon.
I think this page is interesting:
Here's a quote from it:
"The typical western diet is overloaded with omega 6 fatty acids and contains insufficient omega 3 fatty acids. The current ratio of omega 6 to omega 3 fatty acids in the U.S. diet is about 10:1 whereas in hunter-gatherer diets it is closer to 2:1. This dietary imbalance in fatty acids (excessive omega 6 and insufficient omega 3) is a fundamental underlying cause of many chronic diseases including cardiovascular disease, many cancers, most inflammatory diseases, and many psychological disturbances."
That's not backed up with data but it's "from the horse's mouth."
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