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. Glad to see they came up with LNA… there is another ALA, Alpha Lipoic Acid, which is often found useful in treating adult-onset diabetes… not even in the same class of acids.

  2. Is there a reason why ALA isn’t listed in the chart? https://33q47o1cmnk34cvwth15pbvt120l-wpengine.netdna-ssl.com/wp-content/uploads/efainfoods.png
    Shouldn’t ALA, like the kind found in Flaxseed, be listed under Omega-3 with the others (LNA / EPA / DPA / DHA ).   Omega 6 shows (LA / AA).
    Does it go by another acronym?

  3. Ben,
     
    The answer is, it’s not a simple 3-6-9-7 issue, and the ratios are theoretical.  Nobody yet knows what ALA is good for, other than to be converted to EPA and DHA (7% conversion according to this string).  On the other hand, GLA is an n-6, but is thought to be quite useful (I mostly deal with mental health issues, and GLA is a definite mood enhancer if nothing else).
    Olive oil contains triacylglycerols and small quantities of free fatty acids, glycerol, pigments, aroma compounds, sterols, tocopherols, phenols, unidentified resinous components and other (Kiritsakis, 1998).  I’m not sure about triacyglycerols, but if I remember right they are n-7s, which takes them clean out of the 3-6-9 thing.

  4. So avoiding any polyunsaturated vegetable oils, it’s best to stick with saturated oils for cooking (coconut, animal fats, etc)..
    BUT why is mono-unsaturated Extra Virgin Olive Oil often touted for salad dressings?
    Seems every Mediterranean study concludes that olive oil is the key, yet  the Omega-6 to Omega-3 ratio is horibble, so what is it that  makes it so healthy?
     

    • Good question. Olive oil is best consumed in moderation, and I don’t recommend cooking with it.

      • Same question as Carol – what on earth do we cook with? You’re also suggesting we eliminate a ton of foods that benefit our health by providing essential vitamins and minerals (eggs, whole grains, avocados and raw nuts). How do we get all the other vitamins and minerals into our body if we’re turning our whole diet upside down just to avoid omega 6?

    • I think what makes olive oil particularly healthy is the omega 9, which helps control blood sugar and raise HDL. It certainly is beneficial for me, both when eaten and when used topically as a moisturizer.

  5. Have you seen a diet built around low carbs & low omega-6s.  I eat a low carb diet with nuts as snacks.  It is tough to eat LC and give up nuts.  Any thoughts?

    • That’s a great question, and a controversial one. There are prospective studies that suggest nut consumption is beneficial. On the other hand, we know that an elevated n-6:n-3 ratio is a risk factor for many diseases. One possibility that has been pointed out, which I tend to agree with, is that the n-6 in whole foods like nuts has a different effect on our bodies than the n-6 found in industrial seed oils and processed food. Whole foods like nuts contain antioxidants and n-3 in addition to n-6, which arguably mitigate the pro-inflammatory effects of n-6. Also, if you eat the nuts soaked/raw, rather than roasted, they haven’t been cooked and there’s less of a chance that the n-6 is oxidized, which exacerbates its inflammatory effect.

      I tend to think that nuts in moderation (i.e. a small handful a day, or every other day) are beneficial. However, to play it safe, it may be wise to favor nuts low in n-6 like macadamia and filberts and avoid or limit nuts high in n-6 like walnuts and brazil nuts.

  6. I love the picture of the sardines….chocolate sardines!  Not much of an omega 3 boost there, I would imagine.
    Take home for me  is that the most effective way to get your balance of fats in order is to do a big reduction in intake of omega 6’s.   That seems the most effective way to get the ratios aligned.

    • Rick,

      It’s still important to get some omega-3 even if you reduce omega-6 significantly, but yes, I think overall it’s more important for most people to focus on reducing n-6.

  7. @ Alfredo – Recent studies are showing that the oversimplification is in what constitutes “good” and “bad” cholesterol.  It is not so simple that HDL=”good” and LDL=”bad”.  The pharmaceutical industry has us believing whatever they want us to, just to sell more anti-cholesterol drugs, all of which have many more effects than they are prescribed to treat.

  8. Hi All. Very interesting information but complicated to be practical in the day to day living. There is a practical blood test that will give an indirect idea of your omega 6/omega 3 ratio: HDL cholesterol/triglycerides.

    Since the consumption of all omega 6 increase triglycerides and decrease hdl cholesterol and omega 3 works in the opposite direction, this ratio gives good information. The ideal ratio HDL cholesterol/triglycerides is close to 1/1.

    Eating fish has no problems, if you don’t do it too often. But if you want to supplement your diet with the proper amounts of omega 3 by just eating fish, it could be a health risk. You would have to eat fish almost every day and that could mean dangerous amounts of mercury in your nervous system.

    It is important to have in mind that there are certain conditions to get the benefits fish oil can bring.

    You need to take a good quality fish oil, free from mercury and other contaminants. That is a molecularly distilled fish oil.

    Then, you need to take a minimum amount of fish oil, krill oil or cod liver oil at a certain frequency.

    There is not an establish amount of omega 3 for any health benefit but I recommend to take at least 900 mg per day of omega 3 fats (close to 3.000 mg of fish oil), EPA plus DHA, per day. You should increase these amounts if you are overweight or you have degenerative disorders, like hypertension or high triglycerides.

    Also, you should lower your intake of omega 6 fats (mostly grains and grain oils) since omega 3 and omega 6 counteract each other in the body. The best way to reduce omega 6 fats is to eliminate all starches from your diet, that is all grains and grain oil.

    Please read more at http://www.omega-3-fish-oil-wonders.com/essential-fatty-acids-eicosinoids.html
    Best wishes,
    Alfredoe

  9. @nicole I totally disagree that fish oil supplements are a waste of money. I’m taking 4 grams of fish oil per day, and they do more for me than any of the psych drugs ever did, with no “side” effects. And I’m taking the cheapest fish oil available (from Puritan’s Pride).
    As for mercury, all of the major sources of fish oil have been tested, and no mercury or other toxins have been found even in parts per billion.

  10. I have recently changed my diet to include oily fish for the fatty acids, but I too am very concerned about toxicity. Looking forward to your post on the toxicity of fish.  I agree 100% on most supplement omega oils being a waste of money.

  11. Seems that fish oil would have to be refined to have over 60% PUFA’s.  Not all PUFA in fish oil is EPA and DHA.  Additionally, even COLD water fish have over 20% of fat stored as MFA’s and another 20% plus stored as SFA’s.  With fish oil, you are also going to get some BAD PUFA’s, whose rapid oxidization and damage to your body is likely to interfere with any benefits from the EPA and DHA (were they even to get to your tissues without  oxidizing first!).
    I can’t believe that there are “proper ratios” of these fats.  This just does not make sense for a hunter gatherer environment in a feast/starve/feast/starve cycle or for human survival beyond the ocean.  Omega-3’s are now being promoted by the same health professionals who brought you Omega-6’s, in part, to counteract the damage of the Omega-6’s!
    Since all PUFA’s oxidize rapidly upon entering a mammal, where the body temperature is close to 100 degrees, you need lots of Vitamin E to handle these oils.  Our body temps are not those of fish and we developed in warm climates, where SFA’s and MFA’s are far more beneficial.
    Chris has made his case for DHA.  Even if he is right, he has concluded that REAL food (fish) is the best possible source of this PUFA.  And after you cook the fish, subjecting the PUFA’s to 200 degrees or more, what do you think you get from those oils which can possibly be healthy?
    If only a piece of fish per week and avoiding all possible sources of vegetable oils is what you take away from this discussion, Chris will have done a great job helping you to improve your health.

    • Aside from the Asians eating their fish raw (not sure how much they cook it, but I know of sushi) I’m sure the latter two countries he named cook their fish. If this is true how are their concentrations so high?

  12. Once again, we’re only comparing two groups of fats.  Dr. Stoll clearly stated that the optimum fat ratios included Omega-9s.  As I recall the stats (and my memory is far from perfect), the typical American diet (at the time of publication) was 1:9:6 (n-3:n-6:n-9) and that optimum was 1:1:1.
     
    Question:  If 1000 mg of fish oil contains 360 mg of EPA and 240 mg of DHA (standard fish oil, not special concentrates), what is the composition of the remaining 400 mg of oil?

  13. Got it.  I’ll talk more about the relative benefits of fish and fish oil soon.  There is evidence that the EPA &  DHA is better absorbed in whole fish than in purified fish oil.  Still, fish oil is a viable option if it’s a good product (especially if the oil is in the natural triglyceride form).

  14. Doh.. I should have stated Omega-3 supplements derived from fish oil.   For example, Life Extension,  Nordic Naturals and Health from the Sun all contain 1.3g of EPA/DHA Omega-3 from fish oil per serving.

  15. Please read the first article in the series if you haven’t already.  It clearly explains why plant-based omega-3 oils are not acceptable substitutes for EPA & DHA in seafood.  Less than 0.5% of the omega-3 oils in those supplements will be converted into EPA & DHA.  You’d have to take an obscene amount of flax oil each day to get the dose of EPA & DHA you need, but then you’d be taking in way too much polyunsaturated fat which is highly susceptible to oxidative damage.

    Fish oil and DHA oil from algae are alternatives to fish consumption.  I will discuss these in more detail in subsequent posts.

    • Hi Chris.

      Studies claim that ALA to EPA /DHA conversion is poor.

      But what are the omega 6:3 ratios in the study diets?

      It would make sense that little ALA is converted to EPA if the omega 6:3 ratio was high.

      eg for omega 6: 3 ratio of 10:1 (LA:ALA)
      If the affinity for the 2 PUFAs were equal, you would expect a ~10% conversion of ALA to EPA – as LA would be dominating the conversion enzymes due to its concentration being ~9x higher.

      It would be interesting to see the conversion rates of ALA to EPA if the study diet omega 6:3 ratio was 1:1 or 2:1.

  16. It’s a shame that even when you *think* you’re eating healthy (walnuts, almonds, eggs, white meat), your omega-6 to 3 ration will get out of whack!

    I know nutrients in food form are always better than supplementing single nutrients, but  it seems like taking an omega-3 supplement is the most plausible solution.   Is there a reason why that isn’t mentioned as an alternative to eating 11oz fish every day?
    Anyone have any mercury-free omega-3 supplement recommendations? ( Health From The Sun’s Total EFA?  Nordic Naturals?  Life Extension Omega-3s? Equateq Maxomega-90? )

     
     

    • I was wondering if you ever found a supplement that you felt good about. I found one that ensures the purity and potency with a multistep molecular distillation process, which:
      • Concentrates and refines the omega-3 fatty acids
      • Removes lead, mercury, arsenic, cadmium, dioxins, and PCBs, and other contaminants
      • Reduces oxidation and formation of trans fats
      • Minimizes odor and fishy aftertaste
      I sound like a commercial, but I’d be glad to tell you about it. Can you contact me through this site?

    • Raw unprocessed omega 6 such as safflower or sunflower oils do not cause inflamation. Only the processed junk does that. A 2 to 1 ratio of 6 to 3 is morer in line with most all needs of the body where this ratio is what is in the body. Fish is to contaminated and most people can convert plant form. The body converts the amounts of dha and epa it needs and taking the pure epa and dha is very toxic. Mix (1) 8 oz. bottle of flax seed oil with 2 8oz. bottle of sunflower oil.

  17. Fish oils and other food sources that have omega 3 are very important for heart health.  The title How much omega 3 is enough does depend on omega 6, but how do you really know if your omega 3 levels are optimal in your blood.  I would suggest getting an at home omega 3 blood test at http://www.omega3test.com.  The report will tell you if you are really taking enough omega 3 and where your omega 3 and 6 levels are at.

  18. hi baba,
    what about mercury in the fish?  do you have any concerns?
    i just saw “the cove”…  yikes!
    thanks for doing all the math here.
     

    • Hey Tod,

      I’ll be addressing the safety of fish consumption in a future post – possibly the next one. In short, the concern has been way overblown and doesn’t take the protective effects of selenium in ocean fish into account. More to come.

      • Chris, does omega 9 also compete for cellular level assimilation with omega 3, similar to omega 6?

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