An Update on Omega 6 PUFAs

An Update on Omega-6 PUFAs

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Advice to increase omega-3 fatty acid consumption and decrease omega-6 consumption is widespread in health communities and the popular press. But is it omega-6 that’s the problem, or just how we cook omega-6-rich foods? Read on to learn about the benefits of whole foods high in omega-6 and the negative effects of industrial seed oils on human health.

pufas
Good sources of omega-6 such as these nuts, supply the body with essential fatty acids. istock.com/Amarita

Omega-6 is a type of polyunsaturated fatty acid (PUFA) that is essential to human health. In recent decades, however, consumption of omega-6 PUFAs has skyrocketed in developed countries (1), paralleling the dramatic increase in modern chronic disease. This has led many to vilify all forms of omega-6.

I wrote several articles on omega-6 years ago, including “How too much omega-6 and not enough omega-3 is making us sick” and “How much omega-3 is enough? That depends on omega-6.” Lots of new research has been published since then, and it’s important to constantly incorporate new information coming out in the medical literature. This article will thus serve as an update on my previous articles, this time focusing on the source of omega-6.

Omega-6 Is Not a Problem in Fresh, Whole Foods

Today, most consumption of PUFAs is dominated by vegetable oils from soybeans, corn, and sunflower. Before these industrial seed oils were readily available, most of our omega-6 consumption was from fresh, whole foods like nuts, seeds, and pastured meats.

Omega-6 has largely all been grouped together, regardless of the source. But whole-food sources of omega-6 also come packaged with other nutrients like dietary fiber (2), folic acid, niacin, tocopherols, vitamin B6, calcium, magnesium, potassium, phytosterols, polyphenols, vitamin E, and more. Some of these nutrients, like magnesium and vitamin E, have been shown to protect unstable omega-6 fatty acids from being oxidized (3).

Epidemiological evidence supports the idea that different sources of omega-6 might have different effects on health. Nuts and seeds contain large amounts of omega-6, yet are consistently negatively associated with cardiovascular disease (4). A pooled analysis of four prospective studies with follow-up time ranging from six to 18 years found that nut consumption resulted in a 37 percent reduction in cardiovascular-related mortality (5). Nut consumption has also been shown to reduce inflammation (6) and may also reduce risk of type 2 diabetes (7) and cancer (8).

Context does matter, though, and one situation where whole-food omega-6 could potentially become an issue is in people with low intake of omega-3 fatty acids (9). Short-chain omega-6 and omega-3 PUFAs directly compete for the desaturase and elongase enzymes that convert them to their long-chain derivatives. This means that excess omega-6 in the form of linoleic acid may inhibit the conversion of omega-3 alpha-linoleic acid into its long-chain derivatives, EPA and DHA (10). EPA and DHA are components of healthy cell membranes and are particularly important for cardiovascular and neurological health (11, 12). Luckily, as long as we eat adequate pre-formed EPA and DHA in the form of fatty fish, we effectively bypass this issue and can eat whole-food omega-6 without much tribulation.

Should you avoid whole foods high in omega-6?

What Is the Problem? Rancid Vegetable Oils.

The more concerning form of omega-6 is in vegetable oils. Repeated heating of vegetable oils is common practice in the food industry, particularly in large deep-fryers, because it significantly reduces the cost of food preparation. Instead of having to refill their deep-fryers with oil every day, many restaurants add just enough to top it off from the day before, only replacing the entire batch every few days or weeks.

In deep-fat frying, oil is heated to temperatures greater than 400 degrees Fahrenheit, while also being exposed to moisture and air. This causes thermal lipid oxidation, resulting in the formation of polar compounds and yielding new chemical functional groups that deposit in the cooking oil (13). Repeated heating also degrades the natural antioxidant vitamin E (14), which normally protects fatty acids against lipid oxidation.

Several European countries now have national food laws that prohibit reuse of an oil after it exceeds a certain polar compound content level (15). The U.S. has no such regulations (16). However, even the European laws overlook secondary oxidation compounds, which may also be harmful to human health and are not as well studied.

The Effects of Repeatedly Heated Oil on Human Health

Consuming heated vegetable oils has been associated with CVD risk (17), and there is a direct relationship between CVD risk and consumption of cooking oil polar compounds (18). Regular consumption of repeatedly heated vegetable oil has been shown to increase blood pressure (19), decrease nitric oxide (20), and increase total cholesterol (21).

Repeatedly heated oil can also cause vascular inflammation and changes to vasculature that predispose to atherosclerosis (22). Studies have shown that oxidized LDL is much more important than total LDL level at determining atherosclerotic risk (23). Repeatedly heated oil has been shown to increase levels of oxidative stress in the body, including levels of oxidized LDL.

So if the problem is high heat, can unheated canola, soybean, or sunflower oil be a part of a healthy diet? To answer this question, we really need to understand how these oils are made.

What about Unheated Vegetable Oils?

There are three ways that oils are commonly extracted from their source:

  1. Rendering: this method uses heat only
  2. Chemicals: this method uses a solvent (usually hexane) and then subsequent heating to evaporate off the solvent
  3. Press it out: this method is purely mechanical. These oils are commonly labeled as “cold-pressed” or “expeller pressed.”

The majority of oils high in omega-6 PUFAs are produced using the second method. This means that even if you don’t heat your vegetable oil during cooking, it has likely already been heated long before it made its way to the supermarket. It may also have trace amounts of solvent remaining (24). After this extraction process, many oils are further refined, removing even more nutrients (25).

The ultimate result? Energy-dense, nutrient-poor oils. The intense heating used during extraction results in the oxidation of fats and the loss of many beneficial carotenoids, tocopherols, and sterols. Even if you choose a cold-pressed seed oil, you’d still be better off choosing a more nutrient-dense and flavorful option like olive oil or coconut oil.

Conclusions

Given what we’ve learned, here are a few practical tips for modulating your omega-6 intake:

  • Eat real food. Don’t fear the naturally occurring omega-6 in nuts, seeds, pastured meat, and other whole foods, especially if you are eating adequate amounts of omega-3 fatty acids. They are considered essential fatty acids, after all, so you do need some in your diet.
  • Avoid industrial seed oils. Nix these nutrient-poor choices in favor of more nutritious and flavorful cooking fats like olive oil, coconut oil, ghee, and other pastured animal fats. Fats with higher saturated fatty acid content tend to have higher smoke points.
  • Don’t go overboard with the nut flours. This sort of goes along with “eat real food.” While nut flours can be a great substitute for wheat flour in baked goods, they are easy to eat in large quantities, and the omega-6 fatty acids in these have the potential to be oxidized with heating. Switch it up with coconut flour or cassava flour.
  1. Eat pre-formed EPA and DHA. Consuming cold-water fatty fish is a good idea for everybody, but it’s especially important for people that have diets high in omega-6 fats.

Now I’d like to hear your thoughts. Did you shy away from nuts and seeds because of the omega-6 content? Do you avoid industrial seed oils? What are your favorite cooking fats? Share your thoughts in the comments below.

105 Comments

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  1. Hey Chris

    Great post, as always. I stir completely clear of seed oils, only coconut oil, butter and olive oil in my house, oopps , not forgetting the bacon and duck fat 🙂

    Nuts and seeds, I eat a few, but maybe only once a week or less. Not really worried on the O6 content on those, I think replacing all the processed and rancid seed oils, and eating zero modern processed foods likely takes care of the O3/6 ratio pretty nicely.

    I’m with you on taking fish oil and eating oily fish if one is still eating those Omega 6 laden foods and oils, but for the average Joe, eating a standard western diet, are a couple of helpings of mackerel and some fish oil capsules really going to make much of a difference in battling inflammation etc? I mean, how many pills would you have to pop to get those ratios back into a sensible place? 🙂

  2. It’s easy to go overboard with nuts as they’re delicious, and that’s my concern. I do not eat fish often – because of toxic compounds accumulate easily in their cells. And water they’re living in is – well – just in very bad condition (all over the world…). What to do then? Resign from nuts (I mean reduce rather) or deny obvious dangers of fish consumption? Is there another way?

    • You can get EPA and DHA Omega 3 oils from algae oil. The toxins will not have bioaccumulated as much as in fish oils.

  3. Omega 6 fatty acids are superior when they are consumed from raw FRESH whole plant foods and everyone will understand in time.

    Some people may feel better health wise with more Omega 3 fatty acids but I do not. Adrenic Acid and Arachidonic Acid are far superior than DHA and EPA for myself. My cursive handwriting is elegant, efficient and legible when consuming a lot more Omega 6’s than Omega 3’s. All from quality raw FRESH non-rancid whole plant nuts and oily seeds. While consuming a lot of Omega 3’s leads to my cursive handwriting to become too fast, sloppy and quite illegible as if I should be writing an Asian language.

    There is also a lot of poor quality rancid raw nuts and oily seeds that have been shelled and stored for far too long by distributors before being sold to stores for resale. We need to go back in time when we use to grow and shell nuts as needed.

    Some interesting research showing the potential of Omega 6 fatty acids:
    http://www.ncbi.nlm.nih.gov/pubmed/24844257
    http://onlinelibrary.wiley.com/doi/10.1016/S0014-5793(04)00246-7/pdf

  4. I have not limited my nut or seed consumption but have increased vegetables and fish. What do you think about avocado oil?

  5. I have heard that taking calcium supplements may contribute to Alzheimer’s or dementia after menopause. What do you say about this?

  6. Good information.
    I’m still concerned about phytates though.
    I was talking to a biochemist who had done research on brazil nuts and selenium, he came to the conclusion that taking a supplement was better than eating brazil nuts because the selenium was so poorly absorbed (he used bioavailable) due to the anti nutrient content.
    Maybe some information on soaking and redrying nuts would be helpful.
    I have to say nuts have been invaluable in terms of readjusting to primal/paleo but have found my apetite and need for them waned as my blood glucose control improved.

    • Tanya,

      The best way to reduce the phytates in nuts is to soak them in salt water. We put 4 cups of nuts in a mason jar, 1 tbls of Himalayan pink salt, and cover the nuts with filtered water. Let them set for at least 6 hours, then pour off the salt water, rinse, and put in a dehydrator for 24 hours, at no more than 145 degrees.

  7. I’m glad you brought this up because I have been trying to figure out what to do..:I have Sjogrens and I recently read some studies showing that supplementing with GLA (omega 6) is actually helpful to the eyes and joints in people with Sjogrens. So I ordered a bottle Nordic GLA, which is from borage oil. I took it along with my Omega 3 supplement and then started wondering if I was doing the right thing by actually adding more omega 6 to my body. So I haven’t taken it again and figured I need to do more research in deciding if this is good for me or not. Any thoughts or info would be greatly appreciated!!

    • I used to have very dry eyes and was prescribed eye drops – very common, I suppose. Then my mouth was so dry I would wake up in the morning with one side of my tongue stuck to the inside of my lower teeth. It became so bad that the surface of my tongue came away leaving a shiny area. At this point I was tested for Sjogrens. The results came back negative, but my doctor suggested taking Evening Primrose Oil. I also took a good Cod Liver Oil. This has been very helpful. Prior to this I had been taking what could be called a balanced Omega 3/6 supplement – a good brand – along with a good diet, but it wasn’t right for me personally.

  8. I would like to ask about using bacon grease for frying. What do you think? Of course we know about nitrates and they’re not good. I like bacon fat for frying my grass fed beef or beef fat from my bone broth. For all other frying I use coconut oil

    • In preference to your nitrate comment, have you read this article: https://chriskresser.com/the-nitrate-and-nitrite-myth-another-reason-not-to-fear-bacon/?

      I’m ALSO curious about how oxidized the fat from bacon get when its heated high the first time and then reheated, especially since so many people just keep bacon fat on their counter, sometimes in an open container to get even more oxidized. Animal fats seem a little more special though and more dependable than PUFAs as far as oxidation, I mean for centuries people have been keeping animal fats unrefrigerated, and often in open containers. Using animal fats is also a traditional way of preserving foods.

          • Well, pete, considering that the first widely used modern refrigeration system was released sometime in the early 1900’s, the typical household before then would not have been able to “refrigerate” anything… duh… 😉

            • there’s a recipe for pemmican on MSN somewhere. ground smoked meat, pulverized blueberries and rendered beef tallow. keeps for years at ambient temp

              • Sure,animal fat has been rendered for centuries,usually for making soap or candles but John didn’t mention rendering – I can’t find any historical references for storing animal fat for edible purposes..makes sense,as without rendering,the fat would go rancid.

          • I think you’ll find ghee doesn’t need to be refrigerated. Don’t know how widely used it has been among traditional people though. I guess the fats people have used will vary throughout the world. The Weston A Price site would likely have that sort of information. I make ghee myself and use it regularly for frying and roasting, along with coconut oil. I also save the fat from roasted meat. Only use olive oil to drizzle on foods, dressings, etc. Really not sure about the omega 3/6 balance,

  9. Lots of people have been commenting on the omega-6:omega-3 ratio but this article along with things I’ve heard Chris Masterjohn say is that the ratio isn’t that important. Really, it’s more about the quality of the PUFAs and whether or not they are oxidized (which pretty much all nut and seed oils are just from the process of extracting them)

    But what I wish the article would have mentioned is the quality and quantity of omega-6 PUFAs in conventional meats compared to pastured meats. It makes me wonder if it’s the omega-6 ratio that’s an issue in conventional meat really or if it’s all the other aspects of conventional meat that makes it unhealth.

  10. Chris,

    Thank you for a breath of fresh air on O-6 pufa’s, although I suspect the controversy will rage on.

    More to the point, I have been mentally wrestling with my choice to eat about 2 ounces of mixed nuts daily. I know they have some great nutrition, but the O-6 content has worried me ever since the days of Kurt Harris’s Archevore.

    I have relatively good O-3 intake but my ratio has been hard to get below 4 to 1 on O6 – O3. After reading this article I feel more at peace with my current intake of O-6

    I’ll write a post on this in days to come and backlink your article.

  11. I see no one has mentioned chia seeds, the richest plant form of omega-3.

    When I make a tahini-miso spread, I add a tablespoon of chia seeds to help balance out the omega-6 content.

    • ah..but is it bio-available?..and what will you do when new research changes the parameters of ideal omega 3/6 ratio?

  12. What about chicken? That’s high in omega 6. I don’t eat that much, but I cut down on chicken and started eating more fish, and my ratio went down from 9:1 to 4.5:1. Still too high, probably from nuts, but I eat only raw sprouted nuts so maybe not too bad. I’d like to cut out chicken completely, but it’s everywhere, and I don’t always have time to prepare everything myself.

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