It’s quite shocking that polyunsaturated fats are still being touted as “healthy” fats, as the scientific literature clearly shows the damage caused by these types of fats in a multitude of both animal and human studies. Recommending the consumption of polyunsaturated oils for their ‘heart-healthy benefits’ is equivalent (or worse) than the old 20th century medical adage to prescribe smoking as a treatment for sufferers of chronic asthma (true).

“Everyone should have the privilege of playing Russian Roulette if desired, but it is only fair to have the warning that with the use of polyunsaturated fats the gun probably contains live ammunition.” Dr Broda Barnes, MD

For the uninitiated, a quick run-down on the different types of dietary fats:

Polyunsaturated fats are ‘unsaturated’ with hydrogen atoms and contain multiple double bonds in their molecular structure. The highly ‘unsaturated’ nature of their molecular structure makes them incredibly unstable in the presence of heat, light or air (oxygen), and extremely prone to oxidation whether outside or inside the body. Regardless of how many great anti-oxidants you are consuming in your diet (in the form of fresh fruits, etc), it’s not nearly enough to protect your body from the pro-oxidant effects of these polyunsaturated oils. The amount of these types of fats in our diets today is unprecedented, and accounts for the most drastic dietary change in human evolutionary history.

Saturated fats, on the other hand, are ‘saturated’ with hydrogen atoms, contain only single (fairly unreactive) bonds and are heat, light and oxygen stable. They are highly nutritious, traditional fats found in foods and have a protective role in the body, performing countless vital functions. Saturated fats have been the prominent fats in the human diet that have sustained healthy populations worldwide for tens of thousands of years. For those readers not already aware of the benefits of saturated fats (and cholesterol), see Chris Kresser’s articles on the topic. Actually, the benefits of saturated fats and the former maligning of them is finally becoming so widely recognized you could just google ‘the benefits of saturated fats’.

Monounsaturated fats aren’t fully ‘saturated’, but contain only one reactive double bond in their molecular structure (rather than many), making them far less prone to oxidation than polyunsaturated fats. Monounsaturated fats such as olive oil have also had a key role in human dietary history. That said, these oils are still best for cold use only (ie, in their extra virgin form, and not for cooking with at high heat).

Fats found in our diets tend to be a blend of different lipid types, however dietary fats can generally be categorized into predominantly saturated, monounsaturated and polyunsaturated varieties according to their majority degree of saturation, as follows.

The biggest change in our diets in the last 100 years has been the phenomenal increase of polyunsaturated oils in our food supply. The total intake of polyunsaturated fats increased by 2,051% and the intake of canola oil increased by a whopping 16,700%. We’re told to increase these “healthy” vegetable oils and shun traditional animal (saturated) fats, yet where has this got us? Fatter and sicker than ever with soaring rates of diabetes, cardiovascular disease, cancer and obesity.

“Nutritionally I can’t think of a bigger lie than the one claiming that saturated fats are bad for us.” Dr Michael R Eades, MD

The destructive effects of polyunsaturated oils in the body knows very few limits, but these are some of the ways in which polyunsaturated fats adversely affect your health:

• Polyunsaturated fats inhibit thyroid hormone activation, down-regulating metabolism and causing weight gain. Keep in mind that polyunsaturated corn, soybean and flaxseed oils are fed to livestock in order to suppress their metabolisms and cause rapid weight gain for relatively little caloric intake.
• Low thyroid status also inhibits the synthesis of cholesterol to vital steroid hormones in the body, and causes widespread hormonal disruption.
• Polyunsaturated fats contribute to ageing by suppressing cellular respiration and causing widespread oxidative damage to cells and tissues.
• The oxidative damage cause by polyunsaturated fats is also a factor in cardiovascular disease, oxidizing LDL particles and contributing to atherosclerotic plaque formation.
• Polyunsaturated fats block the oxidation of glucose, depriving cells in the body of their preferred energy source (glucose) and causing permanent mitochondrial damage (the Randle Effect or Randle Cycle).
• By depriving the cell of glucose, insulin and blood sugars remain chronically high and this is large factor in the development of insulin resistant diabetes.
• Polyunsaturated fats also suppress the beta cells of the pancreas that are responsible for insulin response, thus further contributing to the development of insulin resistant diabetes.
• Polyunsaturated fats suppress the immune system, lowering resistance to infection and increasing susceptibility to autoimmune conditions.
• Polyunsaturated fats are highly inflammatory, and contribute to inflammatory conditions such as rheumatoid arthritis, acne, asthma, vasculitis, cardiovascular disease and cystitis, to name a few.
• Polyunsaturated fats have been shown to suppress the export of fats from liver cells, and are contributing factors in the incidence of non-alcoholic fatty liver disease.
• Polyunsaturated fats deplete natural anti-oxidants in the body such as glutathione and vitamin E. Vitamin E depletion in particular disrupts reproductive function and contributes to reduced fertility.

Do I have your attention yet?!

Where else do these oils occur in our diets?
Unfortunately, polyunsaturated oils such as canola, sunflower, soybean, vegetable and flaxseed oils are lurking in almost every processed and packaged food product on the market – it’s really no wonder that we’re suffering from world-wide epidemics of obesity, type II diabetes and other lifestyle diseases related to polyunsaturated oil consumption. All fried foods tend to be cooked in these oils, and they’re also found in other benign foods such as eggs, chicken and meat if these animals have been fed corn, soy or flax. Your best bet would be to avoid all margarines, packaged biscuits, cakes, chips, fried foods, muesli bars and similar snacks (including “health bars” and “health snacks” – these are often the worst!) and ensure you’re buying grass fed meats, pastured eggs, real, healthy fats such as cheese, butter, ghee, coconut oil and products made with these natural fats (such as chocolate made with real butterfat or cocoa butter and ice cream made with real cream and egg yolks).

What about nuts and seeds?
Nuts and seeds are slightly less concentrated, more natural forms of polyunsaturated fat than their extracted oils, but are still high sources of polyunsaturated fats nonetheless. In the context of the modern diet already so high in polyunsaturated fats, it would be a little nuts to go nuts on nuts – that includes nut butters, nut milks, nut-based bars, bliss balls, almond meal, tahini, etc. Large quantities of nuts and seeds have never belonged in our diets and actually contain other naturally occurring toxins as well as polyunsaturated fats that diminish their nutrient value (see this article and this post for more). Try cheese and fruit instead (or see this post for more snack ideas), and stick to macadamia nuts (more monounsaturated than polyunsaturated) if you really can’t live without nuts.

And fish oils?
This will really throw you (if you haven’t been confused enough already!). Most short-term studies demonstrate that fish oils have an anti-inflammatory, triglyceride-lowering effect in the body, and this is what we’re always told. However, it has been suggested that this anti-inflammatory action occurs by means of immune system suppression – not a good thing. Long-term studies of fish oil supplementation tend to indicate that these oils are destructive, rather than beneficial, however you’re not likely to hear this view of the fish oil story all that often as fish oil sales aren’t driven up by negative press…

But what about the ‘essential fatty acids’? Aren’t they ‘essential’?
Potentially not! At least, only miniscule amounts of the ‘essential fatty acids’ are needed,if at all.

I’ve dropped enough bombshells for now and I can feel your collective horror building, so I’ll leave that remarkable revelation for another time. For curious readers, the following articles should provide a bit of enlightenment (if you’re not aware of them already):
Errors in nutrition: essential fatty acids
Protective “essential fatty acid deficiency”
How essential are the essential fatty acids?
Unsaturated fatty acids: nutritionally essential, or toxic?
The great fish oil experiment
Precious yet perilous

For those of you with bottles of corn, flaxseed, vegetable, sunflower, safflower and canola oils in the cupboard – dispose of them responsibly or put them to proper use as furniture polish, not for human or animal ingestion.

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Nuts & seeds are for birds & squirrels (not humans!)