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

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.


Join the conversation

  1. I am really interested in finding out – on a restricted diet if I am consuming sufficient? the correct balance of 3-6’s. Considering I do not eat processed foods, foods from fast food outlets, packaged and prepared foods from supermarkets etc….. I would consider I was somewhat deficient in the 6’s (grin) according to modern food eating standards.

    What fats are in my diet? hummmmmm If I cook with oil I use Rice Bran Oil in a 50/50 ratio with butter.
    Any other fats come from meats and fish that I buy fresh and cook at home. Nuts….. well yes, a handful once a week maybe of cashews.

    No Milk No cheese No yoghurt, which has my poor dietician tearing her hair out! I refuse soy milk, wont use rice or oat milk etc…… the shop bought pre packaged milk substitues are frankenfoods as far as I am concerned.

    So am I deficient in the reverse? maybe too much 3’s and insufficient 6’s????

    Maybe maybe not. When I cook with chicken all visibly fat and skin is removed. I am NOT misled by the you must eat low fat rubbish, but I don’t over do it either as I have non alcoholic fatty liver, NO gallstones evident on ultrasound, but do get pain in that area sometimes. Only very recently have I read (here I believe maybe) that tyroid problems can interfere with the liver. I have a multi nodular (growing) goitre and seem to fluctualte tween hypo and hyper……. iodine/kelp supplementation did not agree with me.

    So apart from taking a krill oil capsule once a day, all other fats consumed are natural mostly 3’s I believe…… THOUGHTS appreciated.

  2. McHarris, I share a lot of your sensitivities, not all. Milk and I are good buddies. But the legumes, ah yes. Not many vegetables with any protein in them that I should be eating. And sugars are way up my list too. Sugar plus wheat (aka donuts, cookies, etc.) means eczema, sure as the day is long.

  3. I work with a trained dietician on FAILSAFE method of food chemical sensitivities. I did a huge elimination diet, and under dietician care reintroduced foods one at a time. It works if it is done properly. I am salicylate sensitive, soy and msg intolerant, legumes are a no no for me…. even if soaked and prepared WAP way. Gluten intolerant and casein intolerant…… Makes eating out tricky I tell you, but I now know what I can and cannot eat… at what cost etc…… too much broccoil and I pay the price…. milk and products keep me tied to the house and the loo for days after consuming, and gluten causes me immense pain…. not just in the bowel either. I did undergo some skin prick tests years ago, but they were inconclusive, where as using the R.P.A.H – Failsafe diet has worked for me.

  4. Ya know, most of the “science” on a lot of these issues is so sketchy I’d rather listen to experience. With my ALT-therapies4bipolar group, I get the experience of a lot of people (over 400 right now, maybe 1000 in and out of the group over the years), and when it lines up (as it seems to have on the topics of fish oil, magnesium, and lithium orotate to date), I’d trust that a lot more than a doctor who listens to his pharmaceutical rep.

    No, I don’t want to be contentious. But when you find a good doctor, as I did once and as Lisa maybe has, they SHOW you the evidence and let you try it out. I don’t know what tests her doctor ran, so I can’t comment on the science behind them — but a lot of the “science” in allergy testing is about on the level of The Amazing Randi, a person whose job it is to debunk or cast aspersions, with the benefit going to the drug companies and their own debunkable magic. I will also admit that a lot of the “science” that is pro-allergy is nothing more than pet theories.

  5. An interesting topic – food sensitivity testing. I have to think there’s some gray area between your two opinions. There were some areas on my test results that were questionable to me. For example, I scored high on cow and goat’s milk and low on casein….huh?

    I’ve learned just recently that there are many different types of testing available. The bood testing I had done, I believe is called Cytotoxic food testing….then there’s ACT, Serial End Point Titration & Proactive Neutralization and Electrodermal Titration (VOLS) which is based on orthomolecular medicine.

    I have a good friend who was battling Lyme’s disease and found a treatment approach based on VOLS testing and has been on an amazing road to recovery. This technique is really interesting…it determines your reaction to foods by measuring the electrostatic charge between energy meridians (as in Chinese medicine).

    Anyway, each time I’m sure I’ve found an “answer” I read conflicting sources of information. Makes for an interesting journey for sure, and it’s all good.

    Thanks for your input.

  6. I’m fine with you “disputing” me, but it would hold more water if there was some scientific evidence that supported what you’re saying. The problem with relying only on experience is that it’s subjective and not reliable. Read this for more on why:

    Don’t get me wrong – I value experience as one piece of the puzzle. But I would never advise others on dietary choices based on my experience or even the experience of a group without more evidence to support my recommendations.

    • I use my acupuncturist to clear my allergies. She does a system with the acronym NAET. So far she has helped me clear candidia, animal fat allergy, mold allergy–I breathe better now than I have in 10 years in one treatment, my son’s dad’s dog allergy, which took 2 treatments, and I could go on. Not all acupuncturists do this type of testing and treatment. My family is living proof that it works. Please look into it. It will change your life.

      • I just competed NAET treatment for my allergies. It was done by a chiropractor because there are no acupuncturist in my area that has the treatment. I got ‘cleared’ for gluten. tried it out two days ago to see if my usual symptoms would occur, so far nothing. I’m a believer.

  7. Lisa, I would dispute what Chris says — the standard prick-test allergy tests are pretty rough, give about as many false positives as false negatives (as well as good information), but other testing can be much more accurate. In my own life this has made a great deal of difference, avoiding foods which made me break out into eczema or made me dizzy-ish (anhd other symptoms) instead of taking drugs to “ameliorate” the symptoms. (Any time a doctor prescribes you corticosteroids, he is admitting he doesn’t have a clue.)

    Regular fish oil has a lot less (if any) cod in it, so you might be fine with that.

    Sorry to be “against” you again, Chris, but this is experience for me.

  8. Lisa: most food sensitivity testing is bogus. There’s no support for it in the scientific literature, and I have colleagues that have drawn their own blood twice on the same day, labeled each container with a different name, sent them in to the same lab, and received completely different results for each sample. It’s not at all reliable in my opinion, and I’d think twice about not eating a superfood like CLO based on food allergy testing results.

  9. Thank you, Chris for the great information. I was taking Blue Ice fermented cod liver oil but as of today have to stop. I had food sensitivity blood testing done and today received the results: cod fish is on my list of foods to avoid, so I’m assuming that includes cod liver oil.

    Now I’m searching for an alternative – any recommendations? I’ve already cut out all fried foods, etc. and am eating just meat (grass fed or pastured), vegetables and non-industrial oils/fats.

  10. 1. A does not promote bone loss when D & K2 levels are sufficient. Read this:

    2. Vitamin A is one of the most important fat-soluble vitamins for immune health, along with D. So I do not understand your claim that A & D “increase” compromised immune system. That doesn’t make any sense.

    3. The liver processes toxins – it does not store them. That’s a common misconception. Toxins are stored in the fat tissue. If you’re worried about toxins, you should avoid eating the fat of conventionally raised animals and farmed fish – not liver, which is the most nutrient-dense foods on the planet.

  11. We’ve seen a lot of compromised immune systems from the drugs doctors give to mental patients, and A and D can increase that; also the fact that large amounts of A can advance bone loss, already a hazard in women as they age. While there is also a large amount of nausea and vomiting, sometimes attributed to A and/or D overdosage, it’s always difficult to pin down exactly what causes it. Further, a lot of the psychiatric drugs cause diabetes or pre-diabetic symptoms, and excesses of cod liver oil exacerbates these symptoms or makes treatment more difficult.

    We also prefer fish oil over cod liver oil, as the liver is the major detoxifying organ and there seems to be no standard method of detoxifying cod liver oil; most fish oil is from dark muscle meat, less likely to harbor toxins.

    • I’ve got to second Moss here. I’ve found high dose fish oil a life saver (literally) for my bipolar, but when I tried taking CLO (I got it as a free sample at the WFM where I work) it made me quite ill. I don’t know that it was the vitamin A, but it sure as heck was something.

      PS: Moss, I’d love to here from you about your practice with alternative mental health – I’m struggling to start that kind of practice myself in the Washington DC area!

  12. Moss: what do you mean by “toxicity”? And why do you attribute that to A & D in the FCLO? I respect your experience – I’m the last person to think you need to be an M.D. or licensed practitioner to have an educated opinion. I just think we need to be cautious about drawing conclusions from subjective experience without isolating the variables. That’s the value of clinical research, of course.

  13. I am commenting on behalf of a fairly large group of people I represent, including myself, who take 4-6 grams of fish oil per day. I am not a researcher, just a peer trying to help peers make good decisions. We have experienced toxicity from cod liver oil in our group, perhaps it was a sensitive individual but then most of us taking fish oil for mental health concerns ARE sensitive.

    (There are currently over 400 members of the ALT-therapies 4bipolar Yahoogroup, and perhaps as many as 1,000 or more have passed through the group since our founding in 2002.)

  14. I disagree with Moss on the issue of toxicity of A & D in cod liver oil. A normal dose of FCLO (1/2 tsp/d) would yield approximately 5,000 IU of A and 1,500 – 2,000 IU of D – far below the toxic doses of each. The idea that A is toxic at doses of 20,000 IU per day is incorrect. It’s based on a poorly performed study with results that have been questioned by at least three other groups of researchers. There are many more studies showing that doses as high as 50,000 IU of A are not toxic, especially when D & K2 levels are sufficient (they often are not, which probably explains the toxic effects some experience). Fermented cod liver oil has A, D & K2 which makes it superior to other fish oils in this respect.

  15. Lisa, I think the answer is, follow the money. I have not heard any of the arguments on fermented cod liver oil, but fish liver oils are very high in vitamins A and D, both oil-based vitamins which are not easily eliminated. You can very quickly overdose on these vitamins using regular dosages of fish liver oil.

    As for Dr. Mercola, he owns all or most of the stock in Neptune, the major producer of krill oil. And I believe the disadvantages of krill oil have been stated already in this discussion.

  16. I agree with the WAPF. Vitamin A is not toxic when D and K2 levels are adequate. I’ll be writing more about this at some point.

  17. Chris – Any thoughts on Weston Price Foundation’s recommendation of fermented cod liver oil and the debate running between them and Dr. Mercola’s recommendation of krill oil?

    Also, I’m supplementing vitamin D as my levels were just tested to be at 35. Any danger in over supplementing D with the addition of cod liver oil to the D? Should I be worried abou the D/A ratios?

  18. Janet,
    You might also investigate CoQ10 — I used it to get my doctor off my back on cholesterol levels.  I have been taking fish oil for many years, but it was not enough; it took about 9 months to get my cholesterol down, but the doctor finally stopped ordering tests.  I was taking 2-100 mg capsules per day.

  19. Chris, I’m new to all this information. I was referred to your website because i was taking statins for “high” cholesterol. After reading your articles I told my doctor that I’m throwing away those pills, and now i’m trying to educate myself about these fatty acids. I have been using Smart Balance, which says it’s an “excellent source of omega-3”. It doesn’t list how much omega 6 there is. So i think you’d say throw it away and stick with butter?  Also, i take Fish Oil from SAMs, which has EPA to DHA 3:1. So i guess i’d better check out the other fish oil brands you mentioned, correct? thanks for educating us.

  20. Chris, you are doing a great service.  Thank you.
    I am taking 2 capsules per day of Daily DHA from Wellness Resources. In the product’s description it says: Daily DHA™ contains 582mg of mercury-free marine lipid oil per capsule. This provides 250mg of the highly desirable DHA omega-3 oil and 35mg of EPA per capsule! Daily DHA™ (the same compound used in Leptinal®), is molecularly distilled, ensuring no heavy metals or mercury are in the supplement. It is also a modified fish oil that is very high in DHA and low in EPA. Too much EPA may thin blood too much or actually get in the way of DHA doing its job.*
    I am also following the Paleo Diet and following the 5 rules outlined in the Leptin Diet, but have not switched to grass-fed meats, which I plan to do soon.  I’ve lost 38 pounds since March, my BP is about 120/80 and have stopped taking medication. I have also stopped taking statins for cholesterol.  I take no other meds, including aspirin.  I eat almost no sugar, grains, oils, alcohol, sugar substitutes, or dairy other than pasteurized organic butter.  I do eat a lot of smoked meats.  Any recommendations?  Thanks.

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