Table of Contents
Omega-6 in Fresh Foods | The Problem: Rancid Oils | Impact of Repeatedly heated Oil | Unheated Vegetable Oils | Conclusions
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
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.
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The Effects of Repeatedly Heated Oil on Human Health
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:
- Rendering: this method uses heat only
- Chemicals: this method uses a solvent (usually hexane) and then subsequent heating to evaporate off the solvent
- 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).
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.
- 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.
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I use Ghee, low heat olive oil and expeller pressed organic High Oleic Sunflower Oil.
Would appreciate feedback on the use of the the High Oleic Sunflower Oil. Use it to replace Canola oil for high heat cooking/frying.
Out of interest, why not cut out the sunflower and just cook with the other oils? Or coconut oil and butter?
Are we supposed to have a 1:1 ratio of omega 6 :3 ? How on earth do you manage to achieve / work out this ratio when considering your diet? I also understand that they share receptor sites…. Does that mean they should not be consumed together or you would never know which was absorbed and which wasn’t? Anyone taking black cumin seed oil ? I believe this is high in omega 6, and I take it at the opposite end of the day to my omega 3’s.
Just minimize the 6 and eat fish every couple of days! I get about 4g of omega 6 a day, it’s really easy to balance out 🙂
It is not just the ratio of omega 3 to omega 6. A study showed that rats on a high omega 6 diet got worse when omega 3 was added. The total load of polyunsaturated oils was too high.
Polly, would you please post a reference for your comment? I would love to read that study. Thank you.
I’m following Chris Kressers protocol for SIBO and He is the one saying this ratio is good.
I solved this issue for myself by eliminating oils completely. Part of the reason is that my body doesn’t process fats/oils well and I gain weight quickly on any oil…even the good ones. The rest is that I don’t want the Omega 3 vs. Omega 6 worry as a stressor in my life. I get my healthy fats from fatty fish and dark meat poultry (hormone/antibiotic-free) flax seeds, moderate amounts of nut butter, etc. Since I am an athlete with adrenal issues, I eat a low-fat, high-carb (the good ones) diet and it works for me.
I hear you! We are all different and must do what works for us. 😉
I was wondering about this yesterday as I looked at a table comparing Omega 3 to Omega 6 in whole foods and I thought: there is no way we can keep a ratio of 1:1 even if we remove rancid oils from the diet.
My clients often ask me if nuts and seeds are good?
As you said, I recommend that if we stick to Whole Foods and eat a reasonable amount of nuts and seeds in their whole Form we should not have to worry.
Leaving aside whether the ratio is really that important, It’s not too difficult to get a 1:1 ratio of omega-3s to omega-6s.
A whole foods diet consisting of wild-caught fish (e.g. sardines, salmon, and cod), grass-fed beef and lamb, leafy greens, grass-fed butter, and occasional nuts and seeds will get you there.
It’s when you consume large amounts of nuts, seeds, and meats that have poor ratios that your overall ratio gets out of whack.
Again, I’m not saying a 1:1 ratio is ideal, but it is doable with a nutrient-dense whole foods diet.
You only eat fish,beef,lamb,leafy greens,butter and occasional nuts and seeds?..seriously?
I have been using phosphatidyl choline that has Omega 6 and Omega 3 at a 4:1 ratio
“Variety, moderation, and never stop learning” this is what I always say when people ask me about nutrition. People don’t seem to want to have to learn new things. They want a nice package of knowledge that they can put a bow on and never have to think through it again. My parents, for example, get angry when they hear new information. They feel like they’ve been lied to. I try to explain that we, professionals, doctors, ect, should strive to ever be learning new things.
What do you think about avocado oil? I use the chosen foods Cold Pressed & Naturally Refined. I’m not sure what naturally refined means. Thanks! great post!
I take a completely different view about foodstuffs as I believe that all the damage is done at the farming level,
whereas all the other contributors to most food/health websites are focussing on the ‘after’ issues.
Most farmers these days, especially those that produce large acreages for seed and oil crops, use Roundup or similar products which DO NOT biodegrade in contact with the soil. Wheat especially is doused in this before harvest, as it improves yields by separating the grain from the husks. Since this’ improvement ‘ results in disastrous effects on the health of consumers, the only means of avoidance is to only buy an organic product.
Thanks Beryl. Off-topic? I don’t think so.
I have a minor editing contribution to your post:
“Wheat especially is doused in this before harvest,” should read:
“North American wheat is DOUSED in Roundup IMMEDIATELY BEFORE HARVEST”.
They call it ‘hardening’. Beryl’s technical description of the motivation is doubtless accurate. But effectively what they’re doing is killing the plant, at apex, so no seed is lost. Right B4 harvest, pilgrims.
I’ve removed the word “especially” from your phrase, because the practice is used equally on soybeans, and I dunno what all else.
If you follow the recent movement against the GMO crops, you must be aware that the Roundup from Monsanto is carcinogenic and this information was suppressed by Monsanto while registration of the product in USA years ago. Even Nobel laureates are on payroll for promotion of their products.
Great article! I’ve been meaning to ask and now I take the opportunity: is there a downside with omega 3 enriched eggs? I believe they feed the chickens with flaxseed to make it. I regularly use those eggs as an omega 3 suplement and got curious. These are not organic, but organic eggs are difficult to find here. Thanks!
I raise chickens for they’re eggs and chickens don’t like flaxseeds. My chickens will not eat it. I don’t know how commercial chickens are forced to eat it. Something to think about. If the chicken is free range the eggs will naturally be high in omega 3
I forgot to mention in my earlier post on this article that we consume a lot of nuts now in homemade trail mix. The nuts we use are almost entirely organic (some types are hard to find), and we soak and dry the nuts to reduce the phytates. Also, any nuts that we do not use immediately go into ziplock bags in the freezer.
My wife and I cooked with grapeseed oil for years, because it had a high-heat rating. Then I discovered it had an omega6:omega3 ratio of about 700:1. It was right about the time I was diagnosed as having severe ischemic coronary artery disease. I have no risk factors for heart disease and live a very healthy lifestyle, or so I thought; now I attribute my CAD at least party to this. We now cook only with coconut oil at low-moderate heats, and use olive oil cold on salads and vegetables. Fortunately, I am doing fine now.
My Integrative Physician recommended: Avocado Oil, Grapeseed Oil or Olive Oil. I cook with a combination of all three and my lipid panel is perfect now, for the first time in years. The Grapeseed Oil I use is cold pressed, so maybe that’s what’s working well for me.
The lipid panel is largely useless in predicting heart disease; the correlations are quite low. Read Chris’ white paper on heart disease, and the book “The Cholesterol Myth”. My lipids have always been excellent. Only if you have hypercholesterolemia does it matter, but you would know that with your very first cholesterol test. Those tests cannot tell you if you have systemic inflammation, which is the root cause of heart disease and can be caused by any of a whole host of etiologic factors. There are several dozen things you can do to reduce your risk of heart disease, but paying close attention to cholesterol intake or lipid levels are not among them. Statins are almost a complete fraud. I eat 2-5 eggs a day from my backyard flock, which I started doing *after* being diagnosed with coronary disease, and I am healthier now. To the point of this article, oxidized fats are toxic, and everyone needs to know how to avoid them. For example, I eat nothing deep fried at restaurants any longer, and try to similarly avoid skillet fried foods. At home, I cook at low heats, often sauteing in a small amount of organic vegetable broth, etc. Another book I would recommend is “The Great American Heart Hoax” by Dr. Michael Ozner, cardiologist. And I would definitely NOT recommend Joel Fuhrman’s diet, unless you are very overweight; I am thin and have a high metabolism, and his diet caused my weight to drop to a dangerously low level.
Dawn, Can you share that “easy and delicious to make ” pancake recipe? ( :
What about all those recipes that tell you to ‘toast’ your seeds for greater flavour, before using them. Or put seeds on baked rolls etc. Surely these pracitices will destroy the good oils?
My wife likes to use rice bran oil for frying. High heat and neutral taste. I suggested using macadamia oil, however, she doesn’t like the taste. Also doesn’t like organic coconut oil, although I can eat it. I have not tasted any of these as becoming rancid, however, I do wonder about the acceptability of the rice bran oil. Any clarification on them?
We eat mixed nuts daily. On occasion there is a Brazil nut that seems to be rancid so I’m concerned about that — should I eat it or not, since it is “only slightly” rancid (lol).
We are Type II diabetics and have just started to examine better eating habits. Mainly “meat, potatoes and bread” before. No knowledge about flax seed flour, coconut flour, etc.
Thanks for your articles.
A great summary of things I have been concerned about, and vague on. What about avocado oil? Isn’t it as good as EVOO and coconut oil? It is much more available now (even at Costco), and it is all I use.
Also, are there any studies on long term effects of eating raw nuts versus roasted? Roasted taste so much better, but I am worried I am oxidizing all the goodness out of them.
Any thoughts about ghee- it’s been heated to obtain the results of clarified butter. And then we heat again to consume it. Is it because it is an animal source and not seed that deems this a safe and healthy option?
I have a simple rule of thumb: if you have a persistent greasy mouth feel after eating something, you didn’t eat grease; you ate varnish.
Methinks one of the worst offenders — now that hydrogenated oils have been reduced — are restaurants that stir fry on very hot griddles. A healthy enough oil may have been squirted on the griddle, but what bonds to the food isn’t.
What’s your thought on consuming this PUFAs from vegtable oil raw, for example in a salad? Canola oil is a great source of omega 3 (ratio 2:1 omega 3 to omega 6). Here in Belgium I buy it from a local producer and it is cold-pressed. If cold-pressed and not healted, is it a healthy option?
I also read some comments about the omega 3 in flaxseed being able to transform to EPA and DHA. If I’m not mistaking we humans are actually very bad at this transformatrion, therefore it is good to also eat fish.
Thank you for another awesome article!
Regarding canola oil, it is mostly a GMO in the U.S. and Canada — which why no one who respects their health eats it here:
“As of 2005, 87 percent of canola grown in the U.S. was genetically modified and by 2009, 90 percent of the Canadian crop was genetically engineered.”
It also has many other problems:
Thanks for pointing at the facts we should eat more balanced food.
If we eat a portion nuts (1 oz / 30 g) 2 or 3 times a week, and avoid most of the oils, except a little olive oil for salad, we won’t get too much linoleic acid (w6). Free range poultry or beef are well-balanced in W6 and W3.
I eat twice a week poultry, 2x fish, and 2 x red meat. I balance with some added collagen or hen soup.
We are surrounded by omega-6! So, we’d better take some mix vitamin E and coco oil to neutralize FFA (Free Fatty Acid). Especially if you suffer from an inflammatory disease or if you have depressed thyroid.
You know we tend to store polyunsaturated fatty acids, especially after 45 years. Too much AA in membranes! We’d better reduce intake of PUFA’s, eat homemade, add coconut butter, butter and eggs (to replace SFA from manufactured food) on one side. On the other hand, we do well to neutralize the deleterious effects of excess PUFA’s (storage in the membranes).
How? I give you the floor, for another paper … 😉
PS: Please, don’t say any more omega 3 and 6 are essential… It’s not quite right, except for young children (brain) and pregnant women. Then 3 to 5 g PUFA is a right dose.
Omega-3 and 6 are conditionally essential (in the absence of vitamin B6). Mead acids could do the same, without giving AA (arachidonic acid). A ratio 4/1 or 1/1 (for PUFA) would be OK for most people. Why no more? Pufa’s suppress mitochondrial respiration and stimulate the release of cytokines, activating a variety of immunological and inflammatory processes, when in excess. And there are, for most people!
http://www.sciencedirect.com/science/article/pii/0079683271900383 http://www.ncbi.nlm.nih.gov/pubmed/2120529 http://www.ncbi.nlm.nih.gov/pubmed/14559071 http://www.ncbi.nlm.nih.gov/pubmed/18990554 http://www.ncbi.nlm.nih.gov/pubmed/23900039
Awesome post LucH. You a Ray Peat fan?
Great article, with good information!
Chris, I would also be interested in your opinion on the total amount of PUFAs in the diet. Paul Jaminet, with the Perfect Health Diet, advocates a maximum of about 4% of calories from PUFAs, saying research suggests there are toxic effect from higher amounts. What’s your take on this?
I think Paul Jaminet says 4% from Omega-6. Otherwise, could you provide his quoted % as regards to PUFAs? Thanks.