We live in a time where is seems as if everything under the sun is bad for us. Some even claim the sun itself is harmful to our health! I try and avoid all these overhyped claims. But there is one consumed food substance that deserves more attention. This substance is far more damaging than the commonly feared foods. Yet is still consumed in enormous quantities around the world on a daily basis. It's a substance that even many health conscious individuals are not even aware of. Meanwhile it's consumption is linked to heart disease, obesity and even cancer.
I am referring to Polyunsaturated Fatty Acids. Also known as PUFA's. In particular Omega 6 PUFAs.
According to Wikipedia, PUFA's are:
... fatty acids that contain more than one double bond in their backbone. This class includes many important compounds, such as essential fatty acids and those that give drying oils their characteristic property.
It's interesting that they mention drying oils. Common PUFA oils, such as walnut oil and flaxseed oil, are often used as a wood varnish due to their high oxidation rate. Yes these are the same oils you will see many health proponents add to their daily smoothies...
A PUFA fat is an unsaturated fat as are monounsaturated fats. Being 'unsaturated' means they're lacking a hydrogen atom. In turn they have at least one double bond in the carbon chain. Saturated fats (as found in coconut oil, butter and animal fats) do not lack this bond and have a complete chain.
As you can probably guess, a monounsaturated fat has one double bond, and a polyunsaturated fat has many (or more than one) double bond. Think of double bonds as fractured links in a chain. A chain is only as strong as it's weakest link. Consuming fats that have weak links (double bonds) is not an ideal situation when it comes to health. The weakened chain makes them more vulnerable to oxidation. Oxidation is what happens when atoms of an element lose an electron. But you don't need to worry about the chemistry, think of apple flesh turning brown, or iron rusting. That is oxidation.
Side note: This is why PUFA's are often used as drying oils. When the oil oxidises (loses electrons) it will form a polymer type film on the wood that protects it from damage. Iron is another good example - when iron loses an electron to oxygen it forms iron oxide (also known as iron rust). On the flipside, antioxidants are thought to be beneficial to our health as they reduces the oxidation of other compounds. In theory the antioxidants will help protect our body from oxidation - internal rust so to speak.
In the body oxidation of fatty acids can lead to all sorts of chemistry problems, which of course lead to all sorts of health problems. Problems that I will outline below. One great analogy (borrowed from Paul Jaminet!) is imagining PUFA's as sticks of dynamite and oxygen as an open flame. A cell is a home filled with firecrackers and lit candles - there is a huge potential for things to go wrong.
Now that the chemistry lesson is over, you're probably thinking "What are common PUFA containing foods?" Good question, you don't see food products labelled with 'High in PUFA' at the supermarket (though you will see low in saturated fat labels!)
So where do these PUFA fats live? Omega 3 fats found in oily fish are one source of PUFAs in our food (remember, Omega 3, 6 and 9 are all PUFA fats). But generally oily fish is not the dominant source of PUFA in our diet.
Omega 6 is a lot more common in today's food. Omega 6 fats are found in nuts and seeds. If you think 'oh great, I don't eat many nuts or seeds so my Omega 6 intake must be low' think again. Seeds are today an industrial food staple. Seeds are used to produce the majority of the oils used for cooking in the western world. The oils these seeds produce include soybean oil, corn oil, canola oil, sunflower oil and safflower oil. And our consumption of these oils is growing at an alarming rate.
Total Amount of Omega 6 Calories Consumed Per Person Per Day Over 100 years. Source: Perfect Health Diet Book
If you have any of those oils in your pantry, then you're consuming seed oil. Also, most cafes and restuarants in the western world cook with these seed oils. Even if you cook with butter at home but you eat out on a frequent basis, then you're still being exposed to large amounts of omega 6s.
Finally, though seed oils are the worst offenders for omega 6 polyunsaturated fats in our diet, these PUFA fats also appear in large portions in the following foods:
I have touched on how PUFA's are easily oxidised, but what does this mean for our health? And what are the other health dangers of PUFA consumption?
You would have no doubt heard about the 'health benefits' of omega 3 fats like fish oil. A big reason behind the reported health benefits of fish oil consumption is due to omega 3's anti-inflammatory effects. Omega 6 fats on the other hand have an inflammatory effect on the body. It is well established at omega 3 fats can actually help reduce the damage from high omega 6 consumption - hence why the fish oil industry continues to grow.
I will come back to omega 3's later in this article, but first I want to take a deep dive into the inflammatory effect of excess Omega 6 consumption.
Many health gurus and doctors claim that the levels of omega 3 and omega 6 should stay in a healthy 1:2 ratio in the body. If you're avoiding commercial seed oils, don't use seed oils at home, avoid roasted nuts (or nuts raw nuts in excess), cook your own meals and eat a wholesome diet you maybe pretty close to this ideal balance. But most people don't eat this way all the time!
Most people eat food cooked in restaurants. Will pick up a packaged ready to drink laced with sunflower oil. Snack on cookies or potato chips fried in vegetable oils. Eat roasted nuts, and cook with sunflower oil at hoto to reduce their cholesterol intake!
If you are like 'most' people, then chances are your Omega 3 to 6 ratio is now more like 1:15 if not higher (11).
The average American now consumes 9% of their energy in the form of omega 6 fats. Toxicity levels begin at 4% (17). Some people have been tested to have 3 to 6 ratios of 1:22 and higher!
Once your levels of Omega 6 become too high, you run into all sorts of health problems. The body tries to clear out these extra Omega 6s. Unfortunately, as I mentioned earlier, PUFA's are very unstable. Oxidisation releases free radicals - free radicals cause inflammation in the body - inflammation in the body has been linked to all sorts of illnesses and health issues (some doctors even claim that inflammation is the root cause of ALL health issues).
Chris Kresser has a whole article on the dangers of high Omega 6 levels in the body. You can see the full article HERE, I have included a snippet below:
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
- metabolic syndrome
- irritable bowel syndrome & inflammatory bowel disease
- macular degeneration
- rheumatoid arthritis
- 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:
Remember, seeds have high levels of Omega 6 fats. So if you're consuming soybean oil, corn oil, canola oil, sunflower oil and safflower oil you are consuming a large amount of omega 6. Not only that, but most restaurants use these commercial seed oils for grilling, frying and in dressings.
Finally, it has been shown that excessive intake of Omega 6 has been linked to liver disease, atherosclerosis, obesity, asthma, cancer and even higher mortality rates (15,18,19, 21).
As I mentioned above, PUFA's are easily oxidised. They oxidise when exposed to oxygen. But the oxidation process is accelerated when heated.
Now stop and think for a moment, we've just outlined how omega 6 levels are easily oxidised which in turn lead to a range of health problems. We've also discovered that Omega 6 PUFAs are found in high levels in seeds and nuts. We also know that food manufacturers use these seeds to create cooking oils. Cooking oils that are marketed as 'healthy low in cholesterol' olis. Not to mention their widespread use in restaurants and cafes worldwide.
Take a moment for this to sink in. Oils that are easily oxidized when exposed to heat are used by billions of people every single day to COOK their food.
Even the white paper titled 'Oxidation of food grade oils' published by the Plant & Food Research (20) organisation states:
Preventing oxidation Several different factors can be controlled to reduce the amount of oxidation that occurs in your oil. These include: Temperature - the number one contributing factor of oxidation in oil. If possible reduce the temperature to the lowest possible throughout processing, shipping and manufacture.
Omega 3 and Omega 6 fats are prone to oxidation, especially when compared to heat stable saturated fats like coconut oil. This can be seen on the following graph:
When a PUFA oxidises it produces free radicals, like gamma radiation does to the body - it creates free radicals and creates highly toxic substances like aldehydes. These free radicals react with DNA and proteins creating abnormalities, damaging cell structure and function. Free radicals have been linked to numerous health issues including increased rates of liver disease (21) & acclerated aging (22).
Not only this, but lipid peroxidation (PUFA oxidation) creates a flow on effect. Oxidation of one PUFA leads to oxidation of many more PUFA's (13).
And we wonder why cancer rates are skyrocketing.
Excess PUFA consumption has been linked to higher cancer rates in many peer reviewed studies.
A 1985 rat study looked at various levels of pufa vs saturated fat intake and breast cancer. The researchers found that there was a clear link between increased PUFA consumption and mammary tumorigenesis (1). A study published a year later had the same findings. (2).
The link between PUFA consumption and breast cancer was later shown in a human study. A 1998 paper concluded:
After mutual adjustment of different types of fat, an inverse association with monounsaturated fat and a positive association with polyunsaturated fat were found. Saturated fat was not associated with the risk of breast cancer.(3)
And it's not just woman who need to be concerned, a 2010 rat study found that prostate cancer growth was enhanced with excessive corn oil (high in omega 6's) consumption (16).
Further animal studies have reinforced the link between omega 6 pufa consumption and cancer rates. This 1991 paper concluded:
Experiments on animals have indicated that polyunsaturated vegetable oils promote cancer more effectively than do saturated fats or polyunsaturated fish oils (4)
An 8 year study published in prestigious medial journal The Lancet compared the health effects of a high PUFA, low saturated fat diet, with a low Pufa/high saturated fat diet in 846 men.
The researchers found that 31 of 174 deaths in the high PUFA group were due to cancer, as opposed to 17 of 178 deaths in the low PUFA group. (5)
The links between PUFA consumption and cancer are well established in the scientific community. Yet mainstream media, doctors and marketing continue to preach the benefits of swapping saturated fat for vegetable oils. In New Zealand, we have the Heart Foundation that is meant to help consumers make healthier food choices to improve heart health. Yet you will see their tick on various industrial seed oil products. This image appears on their home page:
Bottles of Canola Oil with the New Zealand Heart Foundation Tick. Source : HeartFoundation Org
Many shun consuming fat when they are trying to lose weight due to fats higher caloric value. Though losing fat is more complex than simply eating less calories (I often help clients lose weight by increasing their fat intake) there is one fat that I tell my clients to avoid eating if they are serious about their fat loss goals (not to mention their health goals). Of course this fat is industrial seed oils high in PUFA.
As obesity rates continue to soar, more and more people are cutting sugar, eliminating saturated fat and trying to eat less food. Despite this society continues to get fatter.
And for those who keep blaming sugar as the problem, please see this graph from the USDA Economic Research Service:
But as sugar consumption falls, intake of PUFA's continue to rise.This graph shows the continued rise of PUFA consumption:
Studies back up the story that these graphs tell. In the Advances in Nutrition Journal, a paper titled Increase in Adipose Tissue Linoleic Acid of US Adults in the Last Half Century (6) researchers show how... " Levels of PUFA fats stored in body fat levels have increased by 136% over the last half century and that this increase is highly correlated with an increase in dietary LA [a PUFA Fat] intake over the same period of time. '
Also, the toxic byproducts of PUFA oxidation can lead to mitochrondria damage, over time weakened mitochondria lead to an assortment of health issues including fatigue and obesity (14). Rat studies further reinforce the link between PUFA consumption and weight gain. This 1993 study tested 3 types of diets on rats. One group had higher levels of saturated fat intake with low omega 6s, the second group had higher levels of olive oil (a monunsaturated fat with moderate levels of Omega 6), and the final group had a high intake of safflower oil (extremely high in omega 6 PUFAS). The researchers found that:
"Despite isocaloric feeding, weight gain was lower in rats fed the more highly saturated diet than in those fed either the high fatty acid Olive Oil diet (7% higher body weight levels than the saturated fat group) or the high omega 6 fatty acid safflower oil diet (12% higher body weight than the saturated fat group)." (15)
Similar results were found in a human study that had two groups consuming the same amount of calories, but the key variable was the type of fats that they consumed. One group was eating a lot of animal (saturated) fats, the second group consumed a lot of PUFA vegetable oils. The PUFA group ended up gaining about 5% more weight than the saturated fat group. Though there are a lot of issues with studies like this, the findings continue to link PUFA consumption with weight gain.
Meanwhile, women who are trying to lose fat around their thighs may find the conclusion of THIS paper interesting:
The [tissue samples of obese woman] analyses showed that the majority of the saturated fatty acids were present in smaller proportions whilst the majority of unsaturated fatty acids were present in larger proportions in the thigh than in the two other sites.
It appears that excess PUFAs are stored around the thigh, while typical human adipose tissues is stored around the abdomen.
If you have read enough health blogs over the years you would have stumbled upon the 'French Paradox'. This term summarises the paradoxical observation that French people have low heart disease rates despite a diet rich in saturated fats (for more on this please read my article 9 Reasons Why Your Doctor Is Wrong About Fat).
There is another, lesser known, geographical health paradox and this is the Israeli Paradox and it is very applicate to this article on Omega 6 PUFAs. The 1996 paper published in the Israel Journal of Medical Science sums it up nicely:
Israel has one of the highest dietary polyunsaturated/saturated fat ratios in the world; the consumption of omega-6 polyunsaturated fatty acids (PUFA) is about 8% higher than in the USA, and 10-12% higher than in most European countries. In fact, Israeli Jews may be regarded as a population-based dietary experiment of the effect of a high omega-6 PUFA diet, a diet that until recently was widely recommended. Despite such national habits, there is paradoxically a high prevalence of cardiovascular diseases, hypertension, non-insulin-dependent diabetes mellitus and obesity-all diseases that are associated with hyperinsulinemia (HI) and insulin resistance (IR), and grouped together as the insulin resistance syndrome or syndrome X. There is also an increased cancer incidence and mortality rate, especially in women, compared with western countries. Studies suggest that high omega-6 linoleic acid consumption might aggravate HI and IR, in addition to being a substrate for lipid peroxidation and free radical formation. Thus, rather than being beneficial, high omega-6 PUFA diets may have some long-term side effects, within the cluster of hyperinsulinemia, atherosclerosis and tumorigenesis. (8)
Barry Groves PhD from Second Opinions explains this nicely:
Polyunsaturated fats (PUFs) are greatly immunosuppressive, and anything that suppresses the immune system is likely to cause cancer. The first person to suggest that polyunsaturated fats cause cancer was Dr R A Newsholme of Oxford University, England. What Newsholme wrote was that when our bodies get sufficient nutrition, our diet includes immunosuppressive PUFs which make us prone to infection by bacteria and viruses. When we are starved, however, our body stores of PUFs are depleted. This allows our bodies' immune systems to recover which, in turn, allows us to fight existing infection and prevent other infections. He was making the point that the immunosuppressive effects of PUFs in sunflower seeds are useful in treating autoimmune diseases such as multiple sclerosis, and that the same fatty acids could be used to suppress the immune system to prevent rejection of kidney transplants.
It was during the early days of kidney transplantation that doctors first encountered the problem of tissue rejection as their patients' bodies destroyed the alien transplanted kidneys. If transplantation were to be a success, they had to find a way to suppress the immune system. Newsholme had said that there was no better way to immunosuppress a renal patient than with sunflower seed oil. So kidney transplant doctors fed their patients linoleic acid. (Linoleic acid is the major polyunsaturated fatty acid in vegetable oils.) But the transplant doctors were then astonished to see how quickly their patients developed cancers: some cancers were up to twenty times as frequent as was expected.
This was in line with heart trials using diets that were high in PUFs which, reported an excess of cancer deaths from as early as 1971. (9)
By now you should be ready to go home and throw out the canola oil sitting in your pantry. But if you think it's that simple, think again.
Industrial seed oils are cheap and easy to use in food manufacture. Not to mention that the average consumer isn't worried about consuming these oils, so manufacturers can use them without worrying about scaring away customers. PUFA's don't have the stigma surrounding them like saturated fat and salt (mistakenly) have.
Thus most processed foods in our supermarkets contain seed oils. Don't believe me? Take a few minutes to check the ingredient lists of items in your pantry. Look for the following words:
They are all high oxidised PUFAS. And the chances are they are already rancid if they were used in a commercial production plant due to the manufacturing processes used.
Even popular 'health bars' contain these oils. Like I said, they're everywhere. And next time you eat out, ask the waiter what oil they cook in. If you're somewhere in the western world I'd say 9/10 they will be using vegetable oils (and often the waiter comes back to report this finding as if it was a good thing!)
Quick story - recently I was in a restaurant in New Zealand, I noticed that the menu listed Duck Fat fries. Though duck fat has some PUFA in it, it is a much lower amount than the oils listed above. Before ordering I asked the waiter to confirm how they were cooked. Her response "The potato is deep fried in canola oil. Once cooked we plate the chips and grate duck fat over them before serving".
I decided not to order the duck fat chips!
Industrial seed oils high in Omega 6 PUFAs continue to be used in kitchens (personal and commercial) all around the world. While traditional (and heat stable) cooking oils continue to be shunned and labeled as 'unhealthy' PUFA consumption continues to rise:
Even if you stop using these oils in your home kitchen, you are still exposed to PUFA's when buying packaged food from the supermarket and resturants.
So how did PUFA fats become so mainstream?
How did this all happen? Why are we cooking in oil that is best use for protecting wood?
It wasn't always this way. A generation or two ago, people used to cook in animal fats - tallow, lard, dripping. The good stuff, low in pufas while high in heat stable saturated fat. In fact, Mc Donalds in Australia cooked their fries in tallow right up until 2004! This from their website :
"we stopped frying with beef tallow back in 2004 and switched to a canola oil blend, as this was a more healthy option for frying".
If there was a face-palm symbol I would insert it here.
The rise of PUFA consumption was a result of 3 key events:
Something happened all these years ago. First, animal products were rationed out with the wars. People could no longer get their hands on animal fats and butter. Enter Crisco and the new hydrogenated vegetable/seed oils. Combine this new product with a MASSIVE marketing campaign at a time where traditional alternatives were scarce and you have a business that is set to make a killing.
This paragraph sums it up perfectly:
"Crisco, first used to make candles, was invented in pre-civil war days by candle maker William Proctor and his brother-from-another-mother, soap maker James Gamble (get it — Proctor and Gamble?)
The meat industry controlled the prices of lard and tallow which were necessary to make soap and candles. As a result, prices were high and so Proctor and Gamble took to acquiring cottonseed mills and with the help of a chemist, developed the process of hydrogenation — turning liquid cottonseed oil into a thick, solid fat, much like lard. And so they marketed it as a replacement to lard. The name “Crisco” came from what they called “crystallized cottonseed oil.”
P&G marketed Crisco as more digestible, cleaner and more economical than lard – perhaps making them the first ever 'healthwashers', a similar strategy they later used to make us think the chemical cocktail of margarine is healthier than butter."
Traditionally, varnishes and paints were made of linseed (flaxseed) oil, soy oil and safflower oil. Around the time of World War 2, chemists discovered how to make paint from petroleum. The result lead to an excess supply of seed oil in the market. What do you do with a 'food' product that no one wants? You feed it to your animal thats what.
Farmers started buying these oils and adding it to their cattle and pig feed. Surprisingly they found that the animals became fatter despite consuming less food. A new market for the seed oils was created. Seed oil producers figured if it was good enough for animals then it was good enough for humans - further increasing their market.
But how did the seed oil producers encourage humans to consume their 'fattening' seed oils? Fear and bad mouthing their competitives products: Butter, Lard and Dripping - fats laden in the 'artery clogging' saturated fat.
The 3rd major event that lead to modern mans consuming excessive amounts of seed oil was due to a fallacy that still exists today. That is the erroneous belief that cholesterol found in saturated fat caused heart disease (if you still believe that please read THIS article).
Some would say it was the perfect storm, others a conspiracy, my thoughts? I will leave this comment: "financial profit at the expense of consumer health is the root of many modern health problems."
I have already listed the names of the oils you want to avoid consuming.
But these two tables may help.
In the table below you want to avoid oils high in BLUE (Polyunsaturated fats):
While in this awesome table that was published on the Functional Alps website you can see common oils ranked from BEST to WORST (i.e. Avoid the oils in the bottom two thirds of the table):
Coconut Oil and Olive Oil are the only oils derived from vegetables that are truely 'safe'. Non-vegetable oils that are also low in PUFA include butter, beef fat and lamb fat.
Yet, when sourcing animal fats, ensure you are buying grass/pasture fed products. As animals fed seeds/vegetable oil products will have higher levels of PUFA fat in their fat (or milk) products.
So what should you cook with? Easy, coconut oil, beef dripping, butter and ghee are all great options. Palm oil is good as long as it's sustainably sourced.
Personally I use lots of beef fat, butter and coconut oil. I aim to avoid cooking in olive oil as it still has a large amount of unsaturated fats. I would be ok with using olive oil as a dressing (i.e. unheated). And if I was eating out I would much rather the restaurant cook in olive oil than canola oil (though coconut oil or butter would be better!) If you know of any restaurants that still cook in traditional dripping or lard PLEASE let me know in the comments section below. I will add the restaurant to my travel list!!
What to do when eating out?
As I mentioned above, always ask the waiter what oil they cook in. You could always ask the chef to cook your meal in butter or olive oil. Or, stick to meals that won't be fried, go with steamed or grilled options. Or even Sous-vide.
What about nuts?
Some nuts are quite high in PUFA fats. For this reason I advise my clients on The Program to keep their nut intake to a minimum. If they are going to eat nuts then always source raw/natural nuts (avoid roasted nuts) or best yet eat raw macadamia nuts due to their low PUFA content.
What about Fish oil? Thats a PUFA fat?
This question is worthy of it's own blog article (I'll get started soon!) but in the meantime here are my thoughts. Yes there are benefits to short term use of fish oil. Especially if ones previous diet was very high in omega 6. If this is the case then a short term bout of fish oil may help minimise the harmful effects of the higher omega 6 levels.
However, using fish oil as a way to justify a high omega 6 diet is like fighting fire with fire. The best method is to lower the omega 6 intake and avoid the extra PUFAs from the omega 3.
Personally, I don't recommend fish oil supplements as you have no control over the oil extraction process, the manufacture process and the transportation and storage of the supplement until it arrives at your home (at which point it should be stored in the fridge). A better way to consume fish oil would be to eat freshly caught seafood or shellfish and ensure it's not over cooked (fresh sashimi would be a good option). The last thing you should be doing with oily fish is deep frying it in vegetable oil whilst thinking it's 'healthy'.
What can I do if I have been eating a lot of vegetable oils during my life?
Firstly, stop using these oils and use saturated fats instead.
Secondly, as it will take the body around 4 years to remove these stored fatty acids in the body, it can be beneficial to supplement with a low dose vitamin E supplement. Dr Chris Masterjohn recommends 1 capsule of Jarrow Formulas, Toco-Sorb, Mixed Tocotrienols and Vitamin E daily for a few years. He explains this in more detail in the video below:
Join Over 30,000+ Subscribers!