AA Levels and Grass-Fed Meats
This is a topic that I've been wondering about for quite some time, and finally decided to do some research on.
My thought is that foods which are identified by Dr. Sears as high in arachidonic acid such as egg yolks and red meat may have those levels determined by the diet which those animals have been fed.
Considering that industrialized hens and cattle are fed a pro-inflammatory diet consisting mostly of grains and animal fats, I think it's a rather safe assumption that those inflamed animals would produce eggs and meat that are also highly inflammatory and contain high levels of arachidonic (or its precursor, linoleic) acid.
My thought then is that those same products should have acceptable AA levels when fed a grass (anti-inflammatory) diet. I haven't found any research specifically related to this, but here's what little I have found. All links are wfs.
This is a post by one of the heads of nutritiondata.com relating the high inflammation index of farmed salmon as compared to wild-caught. Farmed salmon, of course, are fed a grain diet. The poster makes brief mentions of the differing levels of omega-3 and omega-6 fatty acids in grain fed and grass fed beef.
A rather detailed comparison of grain vs grass fed beef. A comparison chart at the bottom of the page states that grass fed has lower levels of omega 6 and higher levels of omega 3. I haven't yet, but will definitely be reading the provided references.
My impression here is that foods which Dr. Sears pins as pro-inflammatory such as red meat and eggs are actually only pro-inflammatory in their industrialized form and are actually anti-inflammatory when acquired from pastured animals.
Thoughts or better resources?
Some data from Kraft et al. 2008 attached below. They examined the lipid content from four beef breeds (2 grass-fed, and 2 grain-fed). The relevant data is in the bottom left of the table, where the arachidonic acid content (20-4 n-6) is shown to be practically similar between the breeds.
It's probably not as simple as labeling a food "pro-inflammatory" based on the AA content. A recent commentary on this paper raises some interesting points:
Interesting, and very detailed, but why the hell didnt they use the same breeds for both feeding methods for a direct comparison?? That looks like what happened.
CLA looks much hight in the GF cows;
The n3 to n6 ratio also looks much better;
cant see the total fat % though..
SFAs look higher in the GF heffers also oddly..
Many primary research papers can be found in PDF form here (including the Kraft paper mentioned previously):
AA being labeled "bad" is a complete result of conventional medicine/nutrition needing to have everything in black & white.
Recall that only recently did U.S. baby formula manufacturers start adding AA to formula because it is absolutely necessary for truly proper brain development (another blow to veganism).
More to read on AA: http://www.bodybio.com/BodyBio/docs/...in-4to1Oil.pdf
This should not be interpreted as being pro-feedlot beef at all, however. Just putting AA in proper perspective.
I dont shy away from eggs(AA), but i dont think i'll take up the bodybio oil, i would think that most folks get enough O6 in their diets without trying, let along by taking 6 table spoons of mostly O6 oil. Ill chow down on some more walnuts.
I agree with Tony here. LA is rightfully classified as an essential fatty acid, but I think it's pretty safe to say that there's no shortage of it in the typical western diet and such a diet undoubtedly contains very high levels of LA and AA.
My impression from the Kraft summary is that, as one would expect in any balanced homeostatic system (including pro and anti inflammatory) too little or too much AA or LA is damaging and it is likely that there is an appropriate level. The real question would be, just what is that level?
I really appreciated the flashback to o-chem and biochem in the pdf. I thought I'd successfully repressed that year of my life. ;)
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