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How Too Much Omega-6 and Not Enough Omega-3 Is Making Us Sick

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In the last article 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. Since EPA and DHA (especially DHA) are responsible for the benefits omega-3 fats provide, and since EPA and DHA are only available in significant amounts in seafood, it follows that we should be consuming seafood on a regular basis.

But how much is enough? What does the research literature tell us about the levels of EPA and DHA needed to prevent disease and ensure proper physiological function?

I’m going to answer this question in detail in the next article. But before I do that, I need to make a crucial point: the question of how much omega-3 to eat depends in large part on how much omega-6 we eat.

Over the course of human evolution there has been a dramatic change in the ratio of omega-6 and omega-3 fats consumed in the diet. This change, perhaps more than any other dietary factor, has contributed to the epidemic of modern disease.

The historical ratio of omega-6 to omega-3

Throughout 4-5 million years of hominid evolution, diets were abundant in seafood and other sources of omega-3 long chain fatty acids (EPA & DHA), but relatively low in omega-6 seed oils.

Anthropological research suggests that our hunter-gatherer ancestors consumed omega-6 and omega-3 fats in a ratio of roughly 1:1. It also indicates that both ancient and modern hunter-gatherers were free of the modern inflammatory diseases, like heart disease, cancer, and diabetes, that are the primary causes of death and morbidity today.

At the onset of the industrial revolution (about 140 years ago), there was a marked shift in the ratio of n-6 to n-3 fatty acids in the diet. Consumption of n-6 fats increased at the expense of n-3 fats. This change was due to both the advent of the modern vegetable oil industry and the increased use of cereal grains as feed for domestic livestock (which in turn altered the fatty acid profile of meat that humans consumed).

The following chart lists the omega-6 and omega-3 content of various vegetable oils and foods:

efa content of oils

Vegetable oil consumption rose dramatically between the beginning and end of the 20th century, and this had an entirely predictable effect on the ratio of omega-6 to omega-3 fats in the American diet. Between 1935 and 1939, the ratio of n-6 to n-3 fatty acids was reported to be 8.4:1. From 1935 to 1985, this ratio increased to 10.3:1 (a 23% increase). Other calculations put the ratio as high as 12.4:1 in 1985. Today, estimates of the ratio range from an average of 10:1 to 20:1, with a ratio as high as 25:1 in some individuals.

In fact, Americans now get almost 20% of their calories from a single food source – soybean oil – with almost 9% of all calories from the omega-6 fat linoleic acid (LA) alone! (PDF)

This reveals that our average intake of n-6 fatty acids is between 10 and 25 times higher than evolutionary norms. The consequences of this dramatic shift cannot be overestimated.

Omega-6 competes with omega-3, and vice versa

As you may recall from the last article, n-6 and n-3 fatty acids compete for the same conversion enzymes. This means that the quantity of n-6 in the diet directly affects the conversion of n-3 ALA, found in plant foods, to long-chain n-3 EPA and DHA, which protect us from disease.

Several studies have shown that the biological availability and activity of n-6 fatty acids are inversely related to the concentration of of n-3 fatty acids in tissue. Studies have also shown that greater composition of EPA & DHA in membranes reduces the availability of AA for eicosanoid production. This is illustrated on the following graph, from a 1992 paper by Dr. William Landis:

percentage of n-6 and n-3 in tissue associated with

The graph shows the predicted concentration of n-6 in the tissue based on dietary intake of n-3. In the U.S. the average person’s tissue concentration of highly unsaturated n-6 fat is 75%.

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Since we get close to 10% of our calories from n-6, our tissue contains about as much n-6 as it possibly could. This creates a very inflammatory environment and goes a long way towards explaining why 4 in 10 people who die in the U.S. each year die of heart disease.

(Note: the ratio of omega-6 to omega-3 matters, but so does the total amount of each.)

In plain english, what this means is that the more omega-3 fat you eat, the less omega-6 will be available to the tissues to produce inflammation. Omega-6 is pro-inflammatory, while omega-3 is neutral. A diet with a lot of omega-6 and not much omega-3 will increase inflammation. A diet of a lot of omega-3 and not much omega-6 will reduce inflammation.

Big Pharma is well aware of the effect of n-6 on inflammation. In fact, the way over-the-counter and prescription NSAIDs (ibuprofen, aspirin, Celebres, etc.) work is by reducing the formation of inflammatory compounds derived from n-6 fatty acids. (The same effect could be achieved by simply limiting dietary intake of n-6, as we will discuss below, but of course the drug companies don’t want you to know that. Less profit for them.)

As we discussed in the previous article, conversion of the short-chain n-3 alpha-linolenic acid (ALA), found in plant foods like flax and walnut, to DHA is extremely poor in most people. Part of the reason for that is that diets high in n-6 LA inhibit conversion of ALA to DHA. For example, one study demonstrated that an increase of LA consumption from 15g/d to 30g/d decreases ALA to DHA conversion by 40%.

Death by vegetable oil

So what are the consequences to human health of an n-6:n-3 ratio that is up to 25 times higher than it should be?

The short answer is that elevated n-6 intakes are associated with an increase in all inflammatory diseases – which is to say virtually all diseases. The list includes (but isn’t limited to):

  • cardiovascular disease
  • type 2 diabetes
  • obesity
  • metabolic syndrome
  • irritable bowel syndrome & inflammatory bowel disease
  • macular degeneration
  • rheumatoid arthritis
  • asthma
  • cancer
  • psychiatric disorders
  • autoimmune diseases

The relationship between intake n-6 fats and cardiovascular mortality is particularly striking. The following chart, from an article entitled Eicosanoids and Ischemic Heart Disease by Stephan Guyenet, clearly illustrates the correlation between a rising intake of n-6 and increased mortality from heart disease:

landis graph of hufa and mortality

As you can see, the USA is right up there at the top with the highest intake of n-6 fat and the greatest risk of death from heart disease.

On the other hand, several clinical studies have shown that decreasing the n-6:n-3 ratio protects against chronic, degenerative diseases. One study showed that replacing corn oil with olive oil and canola oil to reach an n-6:n-3 ratio of 4:1 led to a 70% decrease in total mortality. That is no small difference.

Joseph Hibbeln, a researcher at the National Institute of Health (NIH) who has published several papers on n-3 and n-6 intakes, didn’t mince words when he commented on the rising intake of n-6 in a recent paper:

The increases in world LA consumption over the past century may be considered a very large uncontrolled experiment that may have contributed to increased societal burdens of aggression, depression and cardiovascular mortality.

And those are just the conditions we have the strongest evidence for. It’s likely that the increase in n-6 consumption has played an equally significant role in the rise of nearly every inflammatory disease. Since it is now known that inflammation is involved in nearly all diseases, including obesity and metabolic syndrome, it’s hard to overstate the negative effects of too much omega-6 fat.

In the next article, we’ll discuss three different methods for determining healthy intakes of n-3 that take background intake of n-6 into account.

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424 Comments

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  1. Actually type 2 diabetes is partially hereditary and partially caused by arsenic poisoning. This poison arsenic is in found in substantial quantities in rice both white and brown, pear juice, apple juice and grape juice.

      • Here is a link to *one* study on arsenic and diabetes:
        http://jama.jamanetwork.com/article.aspx?articleid=182413

        There are many more

        Also, arsenic exposure can be from from rice, beer, chicken, brussels sprouts, water (from wells unregulated in the US)….there are many, many studies on this. Too many to list. Here is one relating rice consumption:
        http://www.pnas.org/content/108/51/20656.short

        That said, diseases are caused by *diverse factors*, so arsenic playing a role certainly does not mean that PUFAs don’t also play a role. That would be a very narrow-sighted view. The PUFA evidence is quite convincing. Arsenic may be an *additional* risk factor.

  2. zinzino.com

    Provides bloodtest of your omega 3\6 ratio before you start, and one after 4months to see that your balance is 3:1 or better.

    I had 6:1 before start. Was hoping for much worse because i hoped this could is my backinjury from a car crash, but since i had so nice ratio before starting i had my doubt.
    After 3months daily i felt so much better.
    And after 4months i took the 2nd test that showed ratio 3:1 .

    People have gone from 30+:1 ratio, to under 3:1 .
    They say they have the right amount of omega9 oliveoil in this so that the body will use all amount of the omega 3.

    Youtubevideo from the company:

    • Hashimoto’s thyroiditis is associated with gluten intake, so get her off gluten, also the supplement is not appropriate for her, it should be 18 carbon, plant based omega’s.

  3. I am in school to become a dietitian and just want to say that this article and especially the comments blew my mind. I never knew anything about omega 6 fatty acids and I hope that in the next few years I will have just half the knowledge I see here about the chemical break down of foods. Thank you to all!

  4. I just stumbled across this thread and some basic inaccuracies should be addressed. Omega-6 in its raw, unprocessed form is not the enemy here. The basic problem is the processing which it undergoes. Google vegetable oil processing (corn or canola, soya etc.) it will make you sick. The Omega-6 is actually way more important than Omega-3 for cellular function. Our cell membranes are on average 86% Omega-6 and 14% Omega-3, but it varies depending on cell type (there is virtually no Omega-3 in our skin and only 1% in our brain). Incorporating improper, processed Omega-6 into our cell membranes reduces the rate at which oxygen can cross the cell membrane, leading to anaerobic metabolism, rising acidity levels, inflammation, heart disease and cancer. DHA and EPA are longer chain fatty acids that are highly oxidizable due to there level of unsaturation. They are destroyed by the stomach acid (fishy burps anybody?) and cause a problem for most people. They are not appropriate dietary supplements for most people (if not all).

    • Do you have a website or can you refer me to a specific source so I can gain more information on these points? Thanks.

  5. brill site, especially the comments and info.
    we live in spain and have our own olive trees for oil.
    we cook with it and as is on salads etc.
    Lot said about olive oil which is a subject of its own but the ‘olive oil in moderation’ needs some debate so here is a website to clarify how good it is ( by comparison to others)
    .http://www.aromadictionary.com/oliveoilfaq.html#but%20the%20label%20says%20it%27s%20cold%20pressed
    just had 10 days in UK with almost no olive oil and my arthritis aches are slowly coming back ( just coincidence?)

    • Pedro,

      Are you sure it’s the lack of olive oil causing arthritis problems? Maybe it’s lack of Vitamin D3 due to the lack of sunshine we have here in the UK?

      • Interesting thought. I have far less problem with arthritis-associated muscle aches when I’m in Palestine-Israel and eating lots of olives (I don’t think my consumption of olive oil changes much); I also supplement with D at home in Canada but not when travelling to the Middle East…

    • I’d like the walnut butter recipe, too, please. I’m allergic to both almonds and peanuts and eating a lot of sesame tanini and sunflower seeds and butter. Husband (allergic to peanuts, doesn’t much like almonds) eats a lot of Wow-butter, plus we eat a lot of soy otherwise, so an alternative would be great. Thanks!

  6. I just started eating flax seeds, and my short-term memory suddenly started working again. I could actually feel something happening in my head, and then I was no longer forgetting stuff. I used to do things like walk into a room, and forget why I went there in the first place. I’m guessing it’s because I rebalanced my omega 3’s and 6’s, which is what I was trying to accomplish with the flax seeds.

    • Hi Daniel!

      If you will send me your email I will provide you with information about clinically approved product.
      After you could choose by self to use it or not but will get some usable information.

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  7. Hi Chris

    I love your blog.

    I’m wondering if homemade almond milk would have the high PUF’s especially as the fibre has been strained.

    I was making almond flour with the fibre but have stopped doing this since reading about the high 6 to 3 omega ratio.

  8. Hello,
    My cardiologist tells me that Omega 6’s are inflammatory to the heart. I drink Hemp milk because it’s about the only alternative milk that I can tolerate, but it has a 1:4 ratio of Omega 3’s (1200 mg) to Omega 6’s (3800 mg). Are Omega 6’s from plant sources less harmful than other sources? Is there a distinction? I’m running out of alternative milk options — I have tried several others that don’t agree with me.
    Thanks,
    Aritza

    • Why drink milk at all? For 1000’s of years all we had was water, and it seems to do the job. Just stick to a mostly vegetarian diet and you will put your cardiologist out of business. Vegetable based Omega’s (evening primrose, flax seed, pumpkin seed, safflower oil) are all good in their raw, unprocessed form.

      • But what about bone density. My GP put me on Prolia for my osteopenia but what really helped my numbers the most was I have just through eating more dairy. I am afraid if I get off dairy and my numbers go down again he will recommend the Prolia and I really don’t like taking chemicals.

        • Bone density will take care of itself with proper protein, fats and lower carbs. Milk (non-whole milk) drinking is associated with increased osteoporosis. Also bone strength is associated with weight training. I don’t like the meds either, calcium only stiffens the bone, protein is what gives it strength and resistance to breaking.

          • I thought it was boron that provided tensile strength to bone, though I haven’t studied this for quite a while.

  9. Hey! I was 35kg 13 months ago, I suffer from anorexia. I now weigh 44kg. I eat 2-4 avocado’s a day.. they’re high in omega 6.. So how come I’m yet to gain loads of weight?? I do eat salmon, flaxseed oil, loads of quinoa and a fair bit of omega 3 but I certainly do not think it would outweigh the amount of omega 6 in my diet. My diet is also high healthy low gi carbohydrates.

  10. My experience with omega 6: have you ever heard about ‘Primrose OIL’? It was was prescribed to me by my doctor (never mind what for), who said to take 1000 mg a day. Just after I started taking it as prescribed, I’ve noticed some skin changes, rashes, spots, that recently developed drastically. I blamed it on too much pizza:) Today, I decided to do a little research and I found out that primrose oil contains big doses of Omega 6 and in my case, I don’t really have too much Omega 3, as I don’t eat fish. So, all in all, I decided to stop taking the primerose oil. I know that this kind of natural medicine is becoming more popular and maybe it helps some but after my last experiences I start trusting Doctor Google more than regular ones..

    • I’ve been taking Primrose Oil daily for around 5 years as it cured my PMS. However, I developed a lipoma on my shoulder last month and have just found out according that lipoma could be due to excess Omega 6 intake. I’m continuing to research any connections, but I just wanted to say that just because something is natural and works to cure one ailment, doesn’t mean its safe under all circumstances.

  11. I have found a great oil that contains everything needed it is new to the USA. I had myself tested first. my migrants are gone and I’m overall feeling better.

  12. I too wonder what the asterisk by “Fish” is for. My understanding is that fish does contain some amount of naturally occurring omega 6. So I am surprise to see fish oil contains 0% omega 6.

    I just checked Wikipedia and it says this on fish oil: “The most widely available dietary source of EPA and DHA is cold water oily fish, such as salmon, herring, mackerel, anchovies, and sardines. Oils from these fish have a profile of around seven times as much omega-3 oils as omega-6 oils”

    So this suggests fish does contain some omega 6.

    What the asterisk might indicate is that fish oil capsules might contain little or no omega 6 if the omega 3 in the capsule is concentrated to a high level.

    Such fish oil of course would be of very high quality

  13. So many posts I can’t tell if this question has been answered yet, is sesame oil considered an industrial oil like corn and canola etc?. thanks

  14. Ok, is it fair to say that this article’s thesis is that it’s healthier to balance your omega 3-6. If thats it, then it would also be fair to say any oil is good to cook with as long as you are balancing the other oils with what you intake. Example cooking your fish in an olive oil and a small amount of butter. Would it also be fair to say that every person’s body breaks down fat differently or at different rates? With all the variables in play I find it to difficult to wrap my head around the exact ballance. For the average Joe like myself, I think its best to do ourselves a favor and limit your fats and carbs and get more of your calories from protien and dont worry about what type of fats you are eating as long as you are limiting them. It’s 100% proven that low fat, low carbs, High protien diet works. (Caveman diet, Atkins diet) Then again.. the cancer flock jumps on these diets as well.. as everything causes cancer..go figure.

  15. saturated fats any day= margarine was ok, no health probs’ when Napoleon 111 patented it-twas made with animal fat. became dangerous and a killer when it switched away from animal fats to make it cheaper to produce,and abused plant oils and produced trans-fats-poison.. Now what about Coconut Oil – saturated-but a Medium Chain Triglycerite – Butter-Short Chain Triglycerite -Goose fate-medium chain. I suggest you find out for yourselves about the effects of Long-medium and short chain fats.

  16. It doesn’t seem like Chris is answering comments here, but other readers might be interested in what a scientific study says about PUFA, fatty liver and inflammation.

    I think there’s a big dose of confirmation bias here when Chris only links to studies confirming his believes.

    http://www.ncbi.nlm.nih.gov/pubmed/22492369

    Note that trial was done with overweight people.