How Much Omega-3 Is Enough? That Depends on Omega-6. | Chris Kresser
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How Much Omega-3 Is Enough? That Depends on Omega-6.

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In the first article of this series, we discussed the problems humans have converting omega-3 (n-3) fats from plant sources, such as flax seeds and walnuts, to the longer chain derivatives EPA and DHA. In the second article, we discussed how excess omega-6 (n-6) in the diet can block absorption of omega-3, and showed that the modern, Western diet contains between 10 and 25 times the optimal level of n-6.

In this article we’ll discuss strategies for bringing the n-6 to n-3 ratio back into balance. There are two obvious ways to to do this: increase intake of n-3, and decrease intake of n-6.

Many recommendations have been made for increasing n-3 intake. The important thing to remember is that any recommendation for n-3 intake that does not take the background n-6 intake into account is completely inadequate.

It’s likely that the success and failure of different clinical trials using similar doses of EPA and DHA were influenced by differing background intakes of the n-6 fatty acids. In the case of the Lyon Diet Heart Study, for example, positive outcomes attributed to ALA may be related in part to a lower n-6 intake (which would enhance conversion of ALA to EPA and DHA).

This explains why simply increasing intake of n-3 without simultaneously decreasing intake of n-6 is not enough.

Bringing n-3 and n-6 back into balance: easier said than done!

Let’s examine what would happen if we followed the proposed recommendation of increasing EPA & DHA intake from 0.1 to 0.65g/d. This represents going from eating virtually no fish to eating a 4-oz. serving of oily fish like salmon or mackerel three times a week.

The average intake of fatty acids (not including EPA & DHA) in the U.S. has been estimated as follows:

  • N-6 linoleic acid (LA): 8.91%
  • N-6 arachidonic acid (AA): 0.08%
  • N-3 alpha-linolenic acid (ALA): 1.06%

Keep in mind from the last article that the optimal ratio of omega-6 to omega-3 is estimated to be between 1:1 and 2.3:1. Assuming a median intake of n-6 (ALA + LA) at 8.99% of total calories in a 2,000 calorie diet, that would mean a daily intake of 19.9g of n-6. If we also assume the recommended intake of 0.65g/d of EPA and DHA, plus an average of 2.35g/d of ALA (1.06% of calories), that’s a total of 3g/d of n-3 fatty acid intake.

This yields an n-6:n-3 ratio of 6.6:1, which although improved, is still more than six times higher than the historical ratio (i.e. 1:1), and three times higher than the ratio recently recommended as optimal (i.e. 2.3:1).

On the other hand, if we increased our intake of EPA and DHA to the recommended 0.65g/d (0.3% of total calories) and maintained ALA intake at 2.35g/d, but reduced our intake of LA to roughly 7g/d (3.2% of total calories), the ratio would be 2.3:1 – identical to the optimal ratio.

Further reducing intake of n-6 to less than 2% of calories would in turn further reduce the requirement for n-3. But limiting n-6 to less than 2% of calories is difficult to do even when vegetable oils are eliminated entirely. Poultry, pork, nuts, avocados and eggs are all significant sources of n-6. I’ve listed the n-6 content per 100g of these foods below:

  • Walnuts: 38.1g
  • Chicken, with skin: 2.9g
  • Avocado: 1.7g
  • Pork, with fat: 1.3g
  • Eggs: 1.3g

It’s not too hard to imagine a day where you eat 200g of chicken (5.8g n-6), half an avocado (1.1g n-6) and a handful of walnuts (10g of n-6). Without a drop of industrial seed oils (like safflower, sunflower, cottonseed, soybean, corn, etc.) you’ve consumed 16.9g of n-6, which is 7.6% of calories and far above the limit needed to maintain an optimal n:6 to n:3 ratio.

Check the chart below for a listing of the n-6 and n-3 content of several common foods.

Click the thumbnail for a larger version

Ditch the processed foods and cut back on eating out

Of course, if you’re eating any industrial seed oils you’ll be way, way over the optimal ratio in no time at all. Check out these n-6 numbers (again, per 100g):

  • Sunflower oil: 65.7g
  • Cottonseed oil: 51.5g
  • Soybean oil: 51g
  • Sesame oil: 41.3g
  • Canola oil: 20.3g

Holy moly! The good news is that few people these days still cook with corn, cottonseed or soybean oil at home. The bad news is that nearly all processed and packaged foods contain these oils. And you can bet that most restaurant foods are cooked in them as well, because they’re so cheap.

So chances are, if you’re eating foods that come out of a package or box on a regular basis, and you eat out at restaurants a few times a week, you are most likely significantly exceeding the recommended intake of n-6.

Two other methods of determining healthy n-3 intakes

Tissue concentration of EPA & DHA

Hibbeln et al have proposed another method of determining healthy intakes of n-6 and n-3. Studies show that the risk of coronary heart disease (CHD) is 87% lower in Japan than it is in the U.S, despite much higher rates of smoking and high blood pressure.

When researchers examined the concentration of n-3 fatty acids in the tissues of Japanese subjects, they found n-3 tissue compositions of approximately 60%. Further modeling of available data suggests that a 60% tissue concentration of n-3 fatty acid would protect 98.6% of the worldwide risk of cardiovascular mortality potentially attributable to n-3 deficiency.

Of course, as I’ve described above, the amount of n-3 needed to attain 60% tissue concentration is dependent upon the amount of n-6 in the diet. In the Phillipines, where n-6 intake is less than 1% of total calories, only 278mg/d of EPA & DHA (0.125% of calories) is needed to achieve 60% tissue concentration.

In the U.S., where n-6 intake is 9% of calories, a whopping 3.67g/d of EPA & DHA would be needed to achieve 60% tissue concentration. To put that in perspective, you’d have to eat 11 ounces of salmon or take 1 tablespoon (yuk!) of a high-potency fish oil every day to get that much EPA & DHA.

This amount could be reduced 10 times if intake of n-6 were limited to 2% of calories. At n-6 intake of 4% of calories, roughly 2g/d of EPA and DHA would be needed to achieve 60% tissue concentration.

The Omega-3 Index

Finally, Harris and von Schacky have proposed a method of determining healthy intakes called the omega-3 index. The omega-3 index measures red blood cell EPA and DHA as a percentage of total red blood cell fatty acids.

Values of >8% are associated with greater decreases in cardiovascular disease risk. (Note that n-6 intake was not considered in Harris and von Shacky’s analysis.) However, 60% tissue concentration of EPA & DHA in tissue is associated with an omega-3 index of between 12-15% in Japan, so that is the number we should likely be shooting for to achieve the greatest reduction in CVD mortality.

The omega-3 index is a relatively new test and is not commonly ordered by doctors. But if you want to get this test, you can order a finger stick testing kit from Dr. William Davis’ Track Your Plaque website here. It’ll cost you $150 bucks, though.

What does it all mean to you?

These targets for reducing n-6 and increasing n-3 may seem excessive to you, given current dietary intakes in the U.S.. Consider, however, that these targets may not be high enough. Morbidity and mortality rates for nearly all diseases are even lower for Iceland and Greenland, populations with greater intakes of EPA & DHA than in Japan.

All three methods of calculating healthy n-3 and n-6 intakes (targeting an n-6:n-3 ratio of 2.3:1, 60% EPA & DHA tissue concentration, or 12-15% omega-3 index) lead to the same conclusion: for most people, reducing n-6 intake and increasing EPA & DHA intake is necessary to achieved the desired result.

To summarize, for someone who eats approximately 2,000 calories a day, the proper n-6 to n-3 ratio could be achieved by:

  1. Making no changes to n-6 intake and increasing intake of EPA & DHA to 3.67g/d (11-oz. of oily fish every day!)
  2. Reducing n-6 intake to approximately 3% of calories, and following the current recommendation of consuming 0.65g/d (three 4-oz. portions of oily fish per week) of EPA & DHA.
  3. Limiting n-6 intake to less than 2% of calories, and consuming approximately 0.35g/d of EPA & DHA (two 4-oz. portions of oily fish per week).

Although option #1 yields 60% tissue concentration of EPA & DHA, I don’t recommend it as a strategy. All polyunsaturated fat, whether n-6 or n-3, is susceptible to oxidative damage. Oxidative damage is a risk factor for several modern diseases, including heart disease. Increasing n-3 intake while making no reduction in n-6 intake raises the total amount of polyunsaturated fat in the diet, thus increasing the risk of oxidative damage.

This is why the best approach is to limit n-6 intake as much as possible, ideally to less than 2% of calories, and moderately increase n-3 intake. 0.35g/d of DHA and EPA can easily be obtained by eating a 4 oz. portion of salmon twice a week.

Check out my Update on Omega-6 PUFAs here.

194 Comments

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  1. My omega 6/3 ratio is 2.9. I eat unlimited amounts of paleo-friendly omega 6 foods (nuts, fatty chicken, etc.). I try to take 1 gram of purified fish oil per day (Vitacost Mega EFA) and eat fish only about 3 times per month (due to mercury concerns and cost of good fish). I use tons of olive oil. I try very hard to limit restaurant oils and don’t eat out much these days. I think that if people are focusing on paleo type foods, we should not worry too much about omega-6 content of what we eat. It’s hard enough to eat healthy without worrying about things like nuts and chicken fat. Based on my lab results, I’m actually thinking of cutting back on the fish oil to maybe a couple grams a week.

    • Nuts, avocado and olive oil (surprisingly to most) have very poor 6/3 ratios. Your diet sounds like it’s loaded in omega 6. I would question the lab tests you have referenced.

  2. My husband takes a supplement of omega 3, 6, 9 called complete omega. Since we are already over the top on omega 6’s I have no idea why someone would want to add more mega 6’s into their diet.
    Do kids have same needs?

  3. You say that omega 3’s from vegetable sources do not compare to omega 3’s from fish in terms of total health effects. But, in terms of balancing omega 3’s with omega 6’s, will 1 gram of omega 3’s from flax seed oil create an effective 1:1 ratio if consumed with 1 gram omega 6 oil?

    In other words, when you say the not all omega 3’s are equal; in what ways are they not equal? are they not equal in terms of striking a 1:1 balance of omega3:omega6 ?

    • Hello the answer to your question relates to the way that omega 3 is available to your body. There is an extra step in the process for your body to access and use the omega 3 in flaxseed oil. Still a great choice instead of other high omega 6 oils but fish oil is more readily available to your body.

  4. So if the ratio is 2.3 omega 6 to 1 omega 3, and the recommended dosage of omega 6 for a female is 12g then the omega 3s would equal 5.2g. 1oz chia seeds gives you 97% O-3 and 1tbsp of flax seeds is 54% O-3, both are supper low in O-6 so incorporating them into your diet might do the trick….

  5. The problem with restricting omega-6 so much is deficiency. The DRI is 17g for men and 12g for women or 5-8% of calories for a 2000kcal diet

    • You don’t restrict Omega-6, you restrict processed Omega-6 (canola, soy, corn), that is the truly dangerous Omega in our diet. Unprocessed Omega-6 is ESSENTIAL to the integrity of our cellular membranes esp. the mitochondria.

    • Unless you eat nothing but salmon, you’re not at risk of omega-6 deficiency. Nearly all modern humans ingest omega-6 in excess regardless of their diet. The only exception might be Inuit who eat a very traditional diet of fatty meat and fish with little to no plant food.

  6. You have provided what you speak of as the evolutionary change in human consumption of omega 3 and 6, and stated that in the beginning mankind consumed much seafood and was therefore not deficient in omega 3. But if you go back to mankind in his true evolutionary environment, in the tropics, he was designed to consume fruit and greens, and was not cooking animal flesh. So can we not conclude that our ancestors attained the proper ratio of omega 3 to 6 on plant foods alone?

    • Sure, but when you go that far back what did humans look like ? What were the brain sizes ? Are these humans functionally and nutritionally what we would strive for today ? In other words, just because humans at one point could ‘survive’ on ‘fruits and greens’ by reducing body or organ size or spending all day eating doesn’t mean that is the optimal. In fact changing the diet to a more nutrient dense ‘animal flesh’ based source might be what allowed ‘us’ to out compete those early humans you are talking about. So going back to your ‘true evolutionary environment’ (whatever that means) survival of the fittest, or competition also plays a role in mankind’s ‘true evolutionary environment’. Which means go ahead and continue eating ‘fruits and greens’ and see how you compete against the omnivores of today.

    • Our hunter-gatherer ancestors who didn’t live near rivers or lakes ate grass-fed meat, which is also an excellent source of omega-3.

      You have to go back millions of years before you reach a very distant human ancestor who lived in a tropical environment and didn’t eat meat or fish. All our ancestors in the genus Homo starting with Homo habilis evolved in the African savanna and ate meat in addition to plant food.

      In fact, one of our less distant ancestors, Homo erectus, specialized in hunting elephants. Elephant fat was their main staple food and predominant energy source. This species actually hunted Middle Eastern elephants to extinction after migrating to the Levant from Africa.

      These early humans with their high-animal-fat diet were our direct ancestors.Homo sapiens later evolved from H. erectus populations that had remained in Africa, and also went on to migrate to the Eurasian continent. Upon arrival, our ancestors hybridized with Neanderthals, who – you guessed it – also ate meat. And for tens of thousands of years, there was little else to eat during the Ice Age. Especially during the winter, meat became the only food source.

      If you don’t think it’s possible to live exclusively off meat, look at the traditional Inuit diet. It’s almost entirely meat and seafood. These people suffer no deficiencies (even vitamin C can be gained from semi-raw organ meat) and are actually surprisingly healthy. We’ve perfectly adapted to a high-protein, high-fat, low-carb diet over the past 2.5 million years. This is what has shaped our modern day DNA, not tropical frugivore pre-hominids 10 million years ago.

  7. Just for further reference, here is a quote from Chris which is buried deep in the comments below, that I believe should be put added as a new addendum note at the top of his articles

    “omega 6 in their natural state most often are found beneficial. e.g. look at the studies with nuts , almost every study finds benefits of nut consumption, and most nuts are much higher in omega 6 than omega 3.
    most studies that found omega 6 are harmfull, are done with damaged omega 6, which are added to various foods, spreads etc. These omega 6 are heated, partially hydrogenized, so no wonder their consumption is associated is with diseases. However, omega 6 in their natural state most often are found beneficial.
    IÕve changed my view somewhat on omega-6 from natural sources since writing this article. I think itÕs somewhat unlikely that n-6 from walnuts would cause harm, and of course nuts and seeds have health benefits as you pointed out. Walnuts are also quite high in n-3, which probably explains their effect on arterial flexibility.
    Yes, there is quite a bit of conflicting research on the n-6:n-3 ratio. I may need to revise this article based on what IÕve been reading lately, but the jury is still out.”

  8. These articles are very confusing, bordering on inethical.

    Chris says one thing, and then if you look far down in the comments, he says that he is considering changing his opinion.

    If his opinion is changing then he should change or pull the articles or at minimum, put a little note at the top of each one, stating which points his opinions are evolving since the article was written.

    He pushes everyone in one direction. It’s only the people who troll through all the comments that find out that even he doesn’t entirely believe what he says.

    You can particularly see this in the discussion of damaged omega 6s vs healthy whole food omega 6s, olive oil, etc.

    He seems to write these sensational headlines which pulls people researching the topic to his site and then only a few people find out that in reality doesn’t fully believe everything he has written.

    • Just for further reference, here is a quote from Chris which is buried deep in the comments below, that I believe should be put added as a new addendum note at the top of his articles

      “omega 6 in their natural state most often are found beneficial. e.g. look at the studies with nuts , almost every study finds benefits of nut consumption, and most nuts are much higher in omega 6 than omega 3.
      most studies that found omega 6 are harmfull, are done with damaged omega 6, which are added to various foods, spreads etc. These omega 6 are heated, partially hydrogenized, so no wonder their consumption is associated is with diseases. However, omega 6 in their natural state most often are found beneficial.
      IÕve changed my view somewhat on omega-6 from natural sources since writing this article. I think itÕs somewhat unlikely that n-6 from walnuts would cause harm, and of course nuts and seeds have health benefits as you pointed out. Walnuts are also quite high in n-3, which probably explains their effect on arterial flexibility.
      Yes, there is quite a bit of conflicting research on the n-6:n-3 ratio. I may need to revise this article based on what IÕve been reading lately, but the jury is still out.”

    • We need people like Chris to push the envelope but we still need reductive methods to thoroughly research these areas. Even this one small topic of PUFA ratios is vastly complex and potentially life altering for many people. We need inspirational characters who approach a subject from a fresh perspective but we also need the rigorous scientific method to follow through with solid evidence.

  9. They seem like simple molecules, aren’t omega 3 fatty acids easy to synthesise in bulk, given the state of modern chemistry ?

  10. I find these numbers for pork and chicken somewhat misleading. These are average figures, based on pigs and chickens that are factory farmed and fed almost exclusively corn and soybeans. Given that diet, of course the fat stores on their bodies are going to be made up of the omega-6 fats that they eat.
    If you get pasture raised pork fed on whey from grass-fed dairy animals, and chickens that eat bugs, chia, purslane and/or well-balanced food scraps, the omega-3 to omega-6 ratio can be very well balanced, WITHOUT the mercury content and serious ecological problems of eating so much seafood.

  11. I came across this while looking into the subject at hand.

    Organic production enhances milk nutritional quality by shifting fatty acid composition: a United States-wide, 18-month study.
    http://www.ncbi.nlm.nih.gov/pubmed/24349282

    Abstract

    “Over the last century, intakes of omega-6 (ω-6) fatty acids in Western diets have dramatically increased, while omega-3 (ω-3) intakes have fallen. Resulting ω-6/ω-3 intake ratios have risen to nutritionally undesirable levels, generally 10 to 15, compared to a possible optimal ratio near 2.3. We report results of the first large-scale, nationwide study of fatty acids in U.S. organic and conventional milk. Averaged over 12 months, organic milk contained 25% less ω-6 fatty acids and 62% more ω-3 fatty acids than conventional milk, yielding a 2.5-fold higher ω-6/ω-3 ratio in conventional compared to organic milk (5.77 vs. 2.28). All individual ω-3 fatty acid concentrations were higher in organic milk–α-linolenic acid (by 60%), eicosapentaenoic acid (32%), and docosapentaenoic acid (19%)–as was the concentration of conjugated linoleic acid (18%). We report mostly moderate regional and seasonal variability in milk fatty acid profiles. Hypothetical diets of adult women were modeled to assess milk fatty-acid-driven differences in overall dietary ω-6/ω-3 ratios. Diets varied according to three choices: high instead of moderate dairy consumption; organic vs. conventional dairy products; and reduced vs. typical consumption of ω-6 fatty acids. The three choices together would decrease the ω-6/ω-3 ratio among adult women by ∼80% of the total decrease needed to reach a target ratio of 2.3, with relative impact “switch to low ω-6 foods” > “switch to organic dairy products” ≈ “increase consumption of conventional dairy products.” Based on recommended servings of dairy products and seafoods, dairy products supply far more α-linolenic acid than seafoods, about one-third as much eicosapentaenoic acid, and slightly more docosapentaenoic acid, but negligible docosahexaenoic acid. We conclude that consumers have viable options to reduce average ω-6/ω-3 intake ratios, thereby reducing or eliminating probable risk factors for a wide range of developmental and chronic health problems.”

  12. Oh one more thing. There’s some very good stuff on this website and Chris is very knowledgeable and I have learned many important things from him. I’m not at all trying to discredit the entire website I just am very confident we are incorrect in our interpretations of omega-3 and omega six. The ratio of a omega-6 to omega-3 in the body is actually more than 6 to one. Omega-3 primarily gets burned up in beta oxidation and is part of the process of energy production. Omega six makes up over 20% of the content of cell membranes. It’s particularly important in the one cell layer thick vascular endothelium. But damaged omega six in our modern societies is still getting incorporated. It does not have the ability to maintain membrane fluidity which means that it impairs oxygen transport into cells. This makes the cells relatively hypoxic and this is the initial stage of atherosclerosis. Put healthy Omega 6 in there and watch the process reverse. It has been proven. Go to the Cambridge website. There are tons of articles there for free. The chief research officer is named Brian Peskin and he also has a website BrianPeskin.com where you can also get many of these articles. He additionally has three separate books that you can purchase.

  13. I’m sorry but I feel I have an ethical obligation to let you all know that this is completely wrong. All the studies looking at saturated fats and Omega fats did not consider the fact that the omega six polyunsaturated fats were damaged by processing. This is what you get in every store and every restaurant. You have to switch to organic meats in order to get undamaged omega six. Studies on the content of atherosclerotic plaques done in 1994 and again in 1997 confirmed that there were no fatty acids no omega-3 and very little monounsaturated fat in the plaque. There was also very little cholesterol. The main content of the plaques was damaged omega six. That omega six is damaged before it gets esterified which means it gets linked to cholesterol in the liver after consumption before it gets sent out into your system. You need to go look at the extensive research and literature at the Cambridge international Institute for medical science. I’m sorry to say but we physicians as well as many nutritionists have had it wrong for many years. You can debate me all you want but this particular institute has done extensive research and also has reviewed all the literature for over 100 years on these topics and there is no site out there that can compete with this.

    • Hi Eric,

      I’m very interested in your concerns. Can you please share one or two papers where i can read the information you told us? (i’ve searched but nothing so concrete, so as you seem to be more familiarized with the topic you may have them in your bookmarks or something) 🙂

      Thank you very much

    • Dear Eric, thanks for your post, but still remain the question if the imbalance of the ratio is a real problem, and therefore if it is advisable to reduce at any cost all types of n-6.
      For example, you don’t say nothing about if that high levels in membranes or blood of n-6 are already oxidized or no: they are n-6 and full point. And this imbalance is the culprit of heart diseases.
      Another point to think about is if it is real that the brain shrink when there is lack of n-3. One reason is that the brain replace it with n-6. (oxidized or not), some studies say.
      If it is truth, yes, we should reduce any intake (oxidized or not) of n-6.
      And because of this reasoning you contribute makes any difference at all: we need to reduce at any cost n-6, be oxidized or not.

  14. Why only fish? I’ve heard that we’ve been steered towards fish only because most other animals are fed corn instead of grass and that grass-fed animals have Omega-3 benefits similar to fish. Haven’t read the book but believe this is Paleo concept. Is that not true or at least partly so? As a vegetarian I find both options out of the question so I guess I have to use the other levers available.

  15. You can also get an Omega-3 Index test at OmegaQuant. We are also currently running a spring sale!

  16. This is all great information, but for the layman like myself, it would be a lot more helpful/practical if there were suggested meals to achieve lower n-6 levels and higher EPA/DHA levels. For example, if one was a vegetarian, how could they achieve this? And where can we find a longer list of foods containing a lot of n-6?

    • My understanding is that Hemp derived ptoducts such as Hemp Protein Powder provides the perfect n6 to n3 ratio. Suggest you look it up. And it tastes ok as well. Regards. Sandy

  17. Gongaratulations on your great site! Im deeply concerned with fish eating and consequently fish oil products. Although I love eating them I think its almost certain that we consume toxic metals if not radioactive materials from fish (wild or farmed its the same, since they both live in the same sea waters and the latter being fed with wild fishmeal) As an example I should say that wild fish caught south of Italy had traces of industrial substances from a leakage from a factory in the north of Holland, substances that could only be found there. Radioactivity from Japan has now crossed the Pacific ocean and is now found in the west side waters of the USA and Canada. If we take into account several other ship wrecks and industrial accidents that we will never know about and as salmon producers are using record amount of pesticides and wild fish fishmeal, Im wondering why not taking a tablespoon of flaxseed oil which provides us with 7.2 gr of Omega 3 and just 1.7 of Omega 6 oil? Whouldn’t that be enough within the framework of a plant based diet, with reduced meat intake?

    Cornel Uni research about salmon:
    http://www.news.cornell.edu/stories/2005/12/riskbenefit-analysis-farmed-versus-wild-salmon

    Guardian article about
    Scottish fish farmers using record amounts of parasite pesticides:
    http://www.theguardian.com/environment/2012/sep/10/scottish-fish-farmers-parasite-pesticide

    • Leo,
      I’m wondering if fish oil supplements that have been treated, esp for Mercury, but other toxins as well, would be better than eating fish.
      Thoughts?

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