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Dear Mark: Arachidonic Acid
Posted By Mark Sisson On December 21, 2009 @ 9:57 am In Dear Mark,Diet,Fat,Health,Nutrition | 39 Comments
I spend a lot of time highlighting the importance of omega-3 fatty acids  and downplaying their poly cohorts, omega-6s. Of course, I do this for good reason. Western dietary patterns and modern agricultural practices have made omega-3s harder to come by and blown any semblance of omega-3/omega-6 dietary balance out of the water. As maligned as omega-6s are these days, however, they’re still essential fatty acids. Our bodies need them and can’t produce them on their own – straight and simple. The problem comes when we mistake emphasizing the omega imbalance in modern diets with disparaging omega-6 entirely. Although the Primal Blueprint  promotes a healthy fatty acid balance – one that parallels that of our hunter-gatherer ancestors – I still get questions about omega-6s, particularly reservations about the role arachidonic acid (part of the omega-6 fatty acid family) plays in the PB.
While I totally agree with the importance and value of meat/eggs and vegetables, minus all grains and added sugars…my question is about the arachidonic acid (AA) found mostly in meat and egg yolks. It has been demonized by many, Barry Sears, etc., as the cause of all inflammation in the body. Is that a concern for us on the PB plan?
Arachidonic acid is both a product of the body’s natural linoleic acid conversion and, as the question notes, an existing (but modest) component of animal-based foods like egg yolk and meat – as well as human breastmilk. The particular beef with arachidonic acid revolves around its common conversion to omega-6 derived, “pro-inflammatory” eicosanoids, compounds (e.g. prostaglandins, prostacyclins, thromboxanes, leukotrienes, etc.) that play a role in the intercellular signaling that directs, among other key activities, neurological function and immune response – including inflammatory response. (Eicosanoids are also derived from EPA in the omega-3 family. These are considered anti-inflammatory.) Your proportion of omega-3 derived to omega-6 derived eicosanoids correlate for the most part with your dietary intake of omega-3s and 6s.
Already this correspondence shows that your omega-3 to omega-6 ratio has the most significant impact on your level of omega-6 derived eicosanoids and their inflammatory effects on your system. Consider that the average American has an omega ratio of 20:1, and that’s the ball game. Studies emphasizing the detrimental effects of AA generally focus on the isolated supplementation of AA rather than the impact of supplement when balanced with a correspondingly high intake of omega-3. Research that does gauge the impact of AA supplementation with a high omega-3 intake shows no significant cardiovascular impact . Invited analysis and commentary for the British Journal of Nutrition (which published the original study), citing a number of studies that show little to no appreciable effect of AA on many cardiovascular health and immune function markers, concluded  (PDF) that “moderately increased arachidonic acid intake [designated as up to 1.5 grams or 1500 milligrams] is probably harmless in healthy adults.” Just for comparison sake, the average intake of dietary AA in the Western diet is estimated at 50-300 milligrams a day.
But there’s more reason for reassurance. Much of people’s AA content is likely determined by (and derived from) their high linoleic acid intake (in the forms of corn, soy and vegetable oils). Cut those out of your diet as the PB suggests, and you’re already ahead. As for direct AA dietary sources, chicken eggs weigh in at about 390 mg and 100 gram meat servings generally between 35-100 mg  dependent in part on fat content (organ meat  reach into the 150 mg range). In the context of a healthy omega ratio, the Primal Blueprint’s modest increase in direct dietary arachidonic acid doesn’t present a novel dietary risk as some (like Sears) would have your believe. Next, consider that grass-fed beef is lower in AA than feedlot beef  (PDF). (Remember, it’s not just what you eat but what the cow/pig/chicken/duck/game animal/etc. on your plate ate before it got there. Stuff animals with omega-6 loaded feed and you’ll get meat loaded with forms of omega-6.) Add to this the protective (antioxidant, anti-cancer, pro-cardiovascular health) effects of conjugated linoleic acid (CLA) present in grass fed meats and dairy – up to five times the CLA as you’ll find in grain-fed animals.
Next, there are the other mitigating factors of a Primal Blueprint diet. A healthy, nutrient-rich diet also has some effect on the prevalence of AA from linoleic acid conversion. Linoleic acid, the “parent” omega-6 compound, is broken down by the body into gamma-linoleic acid (GLA). From there, the conversion leads toward either arachidonic acid or dihomogamma-linolenic acid (DGLA), which is actually anti-inflammatory. Minerals like magnesium and zinc and vitamins like C, B3 and B6 appear to encourage the body to redirect GLA conversion toward DGLA  instead of AA. Research shows it’s a more complicated picture – inflammatory and anti-inflammatory.
And if you’re a tea drinker, know that all the steeping and sipping curbs the metabolism of arachidonic acid .
Finally, as I mentioned before, it’s important to keep in mind that arachidonic acid isn’t the bogeyman that it’s made out to be. It comprises a necessary component of cellular membrane structure and supports everything from dermal integrity to muscular growth and repair. It’s no accident that arachidonic acid is present in breast milk. AA plays a critical role in brain development, and a whole host of research comparing AA-supplemented formula with non-supplemented formula underscores this connection. Likewise, AA supports continuing role in neurological health as demonstrated in studies  involving older adults. When it comes to arachidonic acid, the general principle holds: it’s all about overall balance and healthfulness.
Thanks as always for the great questions and comments, and keep ‘em coming!
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 no significant cardiovascular impact: http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=1304684
 concluded: http://journals.cambridge.org/action/displayFulltext?type=1&fid=1304764&jid=BJN&volumeId=98&issueId=03&aid=1304756
 100 gram meat servings generally between 35-100 mg: http://www.ncbi.nlm.nih.gov/pubmed/9590632?ordinalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_SingleItemSupl.Pubmed_Discovery_RA&linkpos=2&log$=relatedarticles&logdbfrom=pubmed
 organ meat: http://www.marksdailyapple.com/organ-meats/
 grass-fed beef is lower in AA than feedlot beef: http://www.csuchico.edu/agr/grassfedbeef/research/lipid/Garcia%202008.pdf
 redirect GLA conversion toward DGLA: http://www.umm.edu/altmed/articles/omega-6-000317.htm
 sipping curbs the metabolism of arachidonic acid: http://pubs.acs.org/doi/abs/10.1021/bk-2003-0851.ch004
 studies: http://content.karger.com/ProdukteDB/produkte.asp?Doi=236447
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