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6 Aug

Why the Omega-3/Omega-6 Ratio May Not Matter After All

unsaturatedfatsWhen it comes to omega-6 fats, the quick and dirty soundbite resonating throughout the ancestral health community has been “omega-6 fats are inflammatory, omega-3s are anti-inflammatory.” Years ago, I wrote a post saying essentially the same thing – that an excessive intake of omega-6s and inadequate intake of omega-3s predispose us to an exaggerated inflammatory response. This sounds right. And the huge discrepancy between the estimated ratio of omega-3 to omega-6 fats in ancestral human diets – 1:3, 1:2, or even 1:1 – and the ratio in modern diets – ranging from 1:25 to 1:10 – just looks pathological. Then, bringing up the rear, you’ve got Bill Lands’ work showing that human populations with low levels of omega-3s and higher levels of omega-6s in their tissues are at greater risk for many diseases like heart disease. It all seems clear cut, no?

Well, kinda. While my general recommendation remains to limit omega-6 fats from vegetable oils, there’s more to the omega-6 story. First, let’s examine the main argument for the importance of the omega-3/omega-6 ratio.

The main argument for the importance of the balanced dietary ratio is that too much linoleic acid (the primary omega-6 fat) increases inflammatory precursors above and beyond the physiological norm, leading to an exacerbated inflammatory response, a general state of systemic inflammation, and the development of the various diseases with an inflammatory root.

Here’s how it’s supposed to work:

Linoleic acid converts to arachidonic acid (AA), a precursor for inflammatory cytokines.

Alpha linolenic acid (ALA; plant omega-3) converts to the anti-inflammatory precursors EPA and DHA, the omega-3 fatty acids we usually associate with fish oil.

Both of these conversions occur along the same rate-limited enzymatic pathway, which means they “compete” for a spot.

If we eat too much linoleic acid, the story goes, our tissue levels of AA will spike and predispose us to excessive inflammation and all the disease fallout that entails. Actually, increasing dietary linoleic acid doesn’t really increase the tissue level of arachidonic acid. Instead, since both linoleic acid and ALA use the same conversion pathway, an excess of linoleic acid does inhibit the conversion of ALA into EPA and DHA, leading to potential deficiencies in the latter nutrients and promoting an inflammatory environment – if you don’t eat preformed EPA and DHA in the form of seafood, pastured animal products, and/or supplements to make up for it.

That’s right: people for whom a fish dinner means battered and fried tilapia sticks are at risk of an inflammatory omega-3/omega-6 ratio, but people following a Primal way of eating are probably safe. Just eating some salmon, sardines, mussels, and pastured eggs can undo a lot of the damage caused when linoleic acid hogs the conversion pathway. Linoleic acid, however, is not directly increasing tissue omega-6 levels.

It appears as if the problem with low ratios of omega-3 to omega-6 is the lack of omega-3, not so much the omega-6. In studies that replace saturated fats with omega-6 fats, the only ones that show benefit are those that also include omega-3s with the omega-6s, while those that replace SFA with just omega-6 increase the risk of death. As long as you’re eating enough fish and other seafood, pastured animals and their fat (and eggs), and/or high quality fish oil supplements, whole food sources of omega-6 shouldn’t increase inflammation. The ratio is a helpful way to monitor your omega-3 and omega-6 intake, but it’s not a physiological law.

That’s not our only issue with linoleic acid, though. Where do we get our omega-6 fats?

No, not you reading this. Not the guy who asks that his eggs be cooked in butter or olive oil at the diner. Not the lady who shudders at the sight of one of those three gallon Costco jugs of corn oil. Where do most people living in industrialized nations get their omega-6s? You know, “normal” people.

Americans get almost 70% of their PUFA (mostly omega-6) from oils, shortening, and margarine and just 6% from beans, seeds, and nuts, 1% from eggs, and 13% from meat, poultry, and fish as of 2004 (PDF). So when we talk about omega-6 intake, we’re really talking about french fries (cooked in vegetable oil), packaged pastries (made with shortening), and processed, high-sugar, high-(vegetable)fat junk food intake.

If most of our omega-6 is coming from the linoleic acid found in cooking oils and processed baked goods, most of the omega-6 we’re eating is highly oxidized, rancid, and maybe even worse.

In one study, just 20 frying sessions were enough to drastically alter sunflower oil, oxidizing the fats and creating cyclic fatty acid monomers which – when eaten – affect fatty acid oxidation, carbohydrate metabolism, and liver enzymes. Dietary linoleic acid that has been oxidized via heat has been shown to directly lead to atherosclerosis. To determine how often most restaurants actually change their frying oil our for new oil, I looked at a topic called “How often do you clean your deep fryer?” in a popular online forum for diner owners. Responses varied from “every day” to “weekly,” with some topping off their oil as they went or relying mostly on filtration of solids. Either way, it’s not very reassuring.

The susceptibility to oxidation may be why diets high in linoleic acid have also been linked to increased oxidized LDL, while diets high in monounsaturated fat – like the traditional Greek diet, rich in extra virgin olive oil – produce considerably lower levels of oxidized LDL.

Omega-6 fat is thus “bad” because the most abundant source of it in our diet is heated vegetable oil, because it’s so susceptible to oxidation, because excessive heating can even create trans-fats out of it, because it’s a proxy for processed junk food, and because it contributes to oxidized lipids in our blood.

But what about whole foods that contain linoleic acid? Are they to be avoided?

Well, let’s look at a few and see what the research says.

Almonds

Both reviled for its linoleic acid and beloved for its easy metamorphosis into low-carb baking meal, the almond assumes a precarious position in the Primal community. But it’s much more than the bag of linoleic acid. An almond contains vitamin E, magnesium, prebiotic fiber, and protective polyphenols. Why does this matter, and how does it relate to the claimed health effects of excess linoleic acid?

Brazil Nuts

Or the Brazil nut, famous repository of “so much omega-6!” Yeah, okay, but it’s also a good source of magnesium, vitamin E, and selenium. We’ve already covered how magnesium and vitamin E can counter any potential negative effects of the linoleic acid they come packaged with, so let’s discuss the selenium in Brazil nuts.

One common complaint about linoleic acid is that it depresses the metabolism by interfering with thyroid function; the Ray Peat fans are fairly adamant about this one in particular. However, selenium is one of the most important pro-thyroid minerals in existence. It allows the conversion of the storage thyroid hormone (T4) into the active thyroid hormone (T3). T3 is what increases metabolism, improves LDL clearance by increasing LDL receptor activity, and generally does most of the positive stuff we associate with the thyroid. And arguably the best, and certainly the easiest, way to get enough selenium is by eating a couple Brazil nuts (a slab of sockeye salmon ain’t too shabby a selenium source, either).

It’s no surprise, then, that a single bout of acute Brazil nut ingestion results in long term depression of inflammatory markers.

Walnuts

Conventional wisdom says walnuts are healthy. Primals worry about linoleic acid intake, and walnuts are loaded with it (along with some ALA). How do they fare in the literature?

Seems they fare pretty well.

Pistachios

Then you’ve got pistachios which, despite their linoleic acid content (13.5g/100g), manage to lower the level of oxidized LDL particles in pistachio-eaters by improving lipids and increasing antioxidant status. They’re also excellent sources of prebiotics, improving the gut microbiota by a greater degree than even almonds.

Hazelnuts

Hazelnuts, which aren’t that high in linoleic acid compared to some other nuts, are quite good at reducing LDL oxidation and inflammatory markers in patients with elevated cholesterol.

Avocados

The avocado is rather rich in linoleic acid (though most of the fat is monounsaturated), leading some among us to avoid or severely limit its consumption. But research in actual avocado-eating humans paints a different story. An avocado eaten with your meal lowers the postprandial inflammatory response, triglyceride increase, and endothelial dysfunction normally associated with meals. Avocados also lower the number of LDL particles in your blood, a significant (and probably real/causative) risk factor for heart disease. I mean, c’mon. No guacamole? No diced avocado in your salad? That’s not living.

It’s tough to reconcile this notion of linoleic acid being wholly bad with the overwhelming evidence for the health benefits of nuts and avocados, and I’ve never really bought into it. Omega-6 intake is strongly associated with age-related macular degeneration, for example, but nut intake is not. And I’m not just talking about epidemiological studies, since those are confounded by the fact that nuts and avocados are generally considered to be healthy foods, and people who eat a lot of them are more likely to do other healthy things, like exercise regularly, drink moderately rather than to excess, eat lots of vegetables, and maintain a healthy weight. The above studies are largely well-controlled, with live human subjects – just like you.

I’m not saying you should eat a cup of almonds every day, or forsake all vegetables save the avocado. I’m simply saying you needn’t fear these foods, for they are undoubtedly healthy foods in reasonable amounts (like most others). Foods. See that word? Fear the isolated, super-heated, burnt fatty acids, if you like. I don’t blame you. But nuts? These are complex nutrient matrices teeming with as-yet undiscovered bioactive compounds. Yeah, maybe one day some enterprising biohacker will identify, isolate, and quantify the effects of every last micronutrient in every food and then create the final perfect iteration of Soylent. Until then, the best option we have is to eat food – whole foods that make us feel and look good, help us perform well, and have solid scientific backing. I’d say that’s a pretty good option.

Linoleic acid in the form of refined vegetable oils is still to be avoided. But I’m just not convinced whole food sources of linoleic acid have the same effect on us. We call out other researchers when they demonize a food we like because of a single component, for good reason. We should be careful not to practice nutritional reductionism to justify demonizing a nutrient we don’t like.

Don’t you think?

Thanks for reading, everyone. Let me know what you think about all this. Did you fear avocados before reading this? Do you still?

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Imagine you’re George Clooney. Take a moment to admire your grooming and wit. Okay, now imagine someone walks up to you and asks, “What’s your name?” You say, “I’m George Clooney.” Or maybe you say, “I’m the Clooninator!” You don’t say “I’m George of George Clooney Sells Movies Blog” and you certainly don’t say, “I’m Clooney Weight Loss Plan”. So while spam is technically meat, it ain’t anywhere near Primal. Please nickname yourself something your friends would call you.

  1. Great post, thanks Mark! We love Avocado! We eat it everyday! :):) YAY!

    Emma and Carla: the merrymaker sisters wrote on August 6th, 2014
  2. Phinney and Volek down pints of sunflower oil *comedic tone*. My guess is excess 6 becomes a fuel and depletes stuff like muscles and hormones. Bit like sugar. But, I doubt it has the insulin response of sugar, insulin problems being close to the core of many a problem.

    Kit wrote on August 6th, 2014
  3. Good article; one nit:

    “or forsake all vegetables save the avocado.”

    Avocado is a fruit, and it sends the fruit signal.

    http://www.jeffreybrauer.blogspot.com/2012/03/signaling-nutrigenomics-made-easy.html

    Jeffrey of Troy wrote on August 6th, 2014
  4. “Omega-6 fat is thus “bad” because the most abundant source of it in our diet is heated vegetable oil, because it’s so susceptible to oxidation, because excessive heating can even create trans-fats out of it…”

    Ok, but what about, if I want to bake a cake with walnuts, almonds or poppy-seeds?
    In this case I heat the vegetable oil in the nuts and seeds. Is it bad, and does omega-6 fat in these baked nuts oxidize, do trans-fats arise out of them?

    Anna wrote on August 6th, 2014
    • My take on it is to eat only raw nuts to avoid any oil-heating issues.

      Energy! wrote on August 7th, 2014
      • Thank you, I think, you ar right, I will also do that, or I bake only occasionally. :)

        Anna wrote on August 8th, 2014
  5. How do cashews fair??

    Joel wrote on August 6th, 2014
  6. It wouls interesting to also hear about the conflicting research on our ability to to convert ALA into EPA and DHA. Some studies say we convert it just fine while others say that we actually convert very little of it.

    Jackie wrote on August 6th, 2014
  7. I could be wrong but I think the absolute amount of omega-6 linoleic acid is of major importance. About 4-1/2 years ago I heard Bill Lands mention that there 4,000 milligrams of omega-6 in each 28 gram, one ounce serving of peanuts. Realizing my mistake, I stopped eating peanut butter sandwiches for lunch. Within two months my leg pains were gone. A year or so later I noticed that my gingivitis had cleared up. At this juncture I have regained much of the strength and stamina I lost as I approached retirement age.

    Once alerted to the omega-6 hazard, as I term it, I began collecting research and articles about the effects of high omega-6 intake. For example, here is a quote from a Joseph Hibbeln interview:

    “But the issue of high fat diets needs to be looked at very carefully. Just as all polyunsaturates are not created equal, all high fat diets are not created equal. A good example of this is an animal study we did where we compared three high fat diets. All with 60% of calories from fat, in mice. We compared high fat diets that resembled the linoleic acid, Omega 6 intakes, comparable to the levels at the beginning of the century, which was about 1 percent of calories, and those high fat diets with 8 percent of calories, more similar to the amount of Omega 6 in the diet simply from soy oil in the U-S diet, today. Moving from 1% to 8% linoleic acid in the mouse diets, not only tripled the levels of arachidonic acids, but also tripled the levels of a critical derivative of arachidonic acids, which is an endogenous cannabinoid, which creates a similar affect to marijuana. So it’s the brains own marijuana like molecules, and we were able to triple the body’s marijuana like hormones, three times higher in the liver and about 20% higher in the brains just by altering the linoleic acid in those two high-fat diets. Normally those high fat diets used for mice in studies are composed of high linoleic acid, found in soybean oil. When we deleted that one single molecule, the Omega 6 fatty acid, we were able to obliterate the ability of a 60% high fat diet to induce obesity in the mice.” http://www.meandmydiabetes.com/2013/03/10/vegetable-oil-associated-with-more-heart-deaths-nih-scientist-joe-hibbeln/

    David Brown wrote on August 6th, 2014
    • Not clear if cannabinoids are good or bad? BTW it’s effect, not affect, unless possibly you’re talking about animation.

      corey b wrote on August 7th, 2014
  8. Just a heads up regarding almonds from Costco. I couldn’t get them to sprout properly and found out they are pasteurized with a gas as opposed to steam.

    Costco brand Kirkland Signature: Both the Kirkland Signature chocolate-covered and whole almonds are fumigated with PPO, which a spokesman said he was told doesn’t remain in the nuts, despite the fact that almonds containing residues of up to 300 parts per million of this chemical, which California regards as a “known carcinogen,” can be legally sold. – See more at: http://foodidentitytheft.com/trying-to-avoid-almonds-that-are-gassed-heres-a-little-guide/#sthash.lKQfsm2j.dpuf

    Nikko wrote on August 6th, 2014
  9. Looks like the long term studies are starting to trickle through about omega 3’s.
    I had to quit taking them for now because of my health issues attributed to them.
    My research lead me to the Dart 2 studies which is kinda alarming. I’ve been
    taking 3-4 capsules a day of a good FOS5 brand for many years now. Since
    I quit, my symptoms are going away. I was originally sucked into the omega 3
    theory many many years ago namely because of the Greenland Eskimo studies.
    Yes, their diet is high in omega 3’s, but NOT an isolate pill form. They eat
    foods that are high in O3’s. That’s the ticket. Stop the isolates and just
    eat real food!

    keithallenlaw wrote on August 6th, 2014
  10. Can you address Chia seeds and their omegas …PLease

    deb wrote on August 6th, 2014
  11. I actually stopped eating nuts completely and feel a lot better (I have gut dysbiosis and thyroid issues, though). I think the problem with Paleo/ Primal diets could be that a lot of people eat nuts almost every single day, and then make desserts with nut flours. Eaten once a week shouldn’t be a problem especially for those with healthy guts but I don’t think Grok ate nuts every single day as a mid-afternoon snack either…

    Ally wrote on August 6th, 2014
  12. What about pecans? I buy the Trader Joe’s raw pecan pieces because they’re cheaper than macadamias, walnuts, or even pistachios.

    And I’m pretty tired of all the bourgeois crooning about “pastured, organic, grass-fed,” blah, blah, blah. An organic chicken is about $6 a pound. Conventional leg quarters can be had for $0.079 a pound! I have to eat. How about some paleo pointers for the poor?

    Oh, yeah, after all the blathering about “resistant starch” (and I’ll try almost anything to improve my gut since I suffer with hereditary chronic diverticulitis) I simply could not find green bananas–until I checked the plantains at a local mercado!

    Corey B. (Long Beach, CA) wrote on August 7th, 2014
  13. And what about seeds? All clear to eat my sunflower/pumpkin/flax mix?

    Krystal wrote on August 7th, 2014
  14. Avocados were never an issue for me. My question is about drinking too much almond milk? If I eat more than a handful of almonds, my lower unit feels it’s affects. So wouldn’t too many glasses of almond milk have the same affect? Good info Mark.

    Mark Naffziger wrote on August 7th, 2014
  15. Another question, should I still soak all nuts in salt water for 24 hr and cook and roast at low heat in the oven ?

    Tannauz wrote on August 7th, 2014
  16. Mark, you are basically arguing that we don’t need to limit omega 6 consumption as long as we get enough preformed EPA/DHA because the harmful effects of omega 6 are confined to it’s tendency to compete with plant based omega 3 for conversion to the active forms.

    HOWEVER, correct me if i’m wrong, but I think that AA also competes with EPA for cell receptors…so an excess intake of omega 6 could still limit the cellular concentration of EPA and create a pro-inflammatory environment.

    Marcus volke wrote on August 7th, 2014
    • I’d be curious too if there are other mechanisms downstream where LA would compete with EPA/DHA. Maybe there just isn’t much literature on this yet. This study did say there is a downstream reaction between LA and arachidonic acid, though not between LA and EPA/DHA: “It is possible that as LA increases in the diet it maybe competing with AA for reacylation into phospholipids.”

      Basically, I don’t think omega-6’s are out of the woods yet, and polyunsaturated fats are still just too vulnerable to oxidation and should be minimized (in high heat cooking) for that reason anyway.

      James Dang wrote on August 22nd, 2014
  17. Thank you Mark for an in-depth analysis of LA and ALA, while making it easy to understand. I truly enjoy understanding the deeper analysis, but some times it tough to understand the details. Your writing style lends itself to fuller understand the details. Keep rocking and rolling! Thanks

    EJLM wrote on August 7th, 2014
  18. I meant to write ‘insurance doesn’t cover my chiropractic’

    David Fyhrie wrote on August 7th, 2014
  19. Didn’t fear avocados and nuts before and don’t fear them now. Eat them in moderation.

    Kamila wrote on August 7th, 2014
  20. Like everyone has said: terrific article! I’ve been Primal for two years and all of my health issues are resolved (now to kick my butt on the fitness aspect!). Becauase I am now so healthy, I’ve given up meaningless obsessions. I do still watch my sugar intake (yes, even fruit) but that’s about it. I’m mostly obsessed that I get the best quality foods in general and eat a wide variety of them.

    Akimajuktuq wrote on August 8th, 2014
  21. While I enjoy the amount of science in your article you failed to mention that linoleic acid and arachidonic acid contribute largely to the production of pro-inflammatory oxylipins within the body. These n-6 fatty acids also compete with omega-3 fatty acids (ALA, EPA, and DHA) for the same enzymes (COX, LOX, and CYP450), however they produce pro-resolving oxylipins. There will always be competition at these enzymes as omega-3 and omega-6 fatty acids are substrates for both of them.

    Melissa wrote on August 8th, 2014
  22. THANK YOU for finally addressing this debate (which has also been going on in the forums). It was really starting to confuse me when I thought I should even limit my avocado intake.

    However, I do wonder about the studies-I assume the subjects were average American eaters. Substituting part of their diet with nuts is likely better than the completely SAD diet they normally eat, in which case a decease in inflammation would be expected. The question is, how would the results differ in the context of a paleo diet that includes nuts regularly versus one that doesn’t?

    Elle wrote on August 8th, 2014
  23. Solid, measured article. Sensible research here on the benefit of replacing refined foods with nuts in type 2 diabetics. Despite one of the authors having multiple ties to the nut councils, I still think the work overall is very good as it isn’t focussing on macronutrient numbers, but pragmatic dietary changes such as replacing one food group for another.

    http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0103376

    Adi Kumar wrote on August 9th, 2014
  24. I just don’t like Omega 3 fatty acids, and it is in high amounts in the packaged food, so I have almost stopped eating packaged food

    Rajesh wrote on August 21st, 2014
  25. OK, Mark, thanks for the nutty info…er, I meant, nut info…but what about pecans? I buy those at Trader’s because they cost less–much less, like half, if you choose the bits and pieces–than the others; even less than pistachios, which you seemed to approve of. Don’t get me wrong, I’m not suggesting making a meal out of them, I just chuck a handful into a salad (instead of cheese, specifically blue or gorgonzola, which was hard for me to give up: but finally got me off the weight loss plateau I’d been stuck on for six months).

    Corey B. (Long Beach, CA) wrote on September 16th, 2014

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