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Ten Reasons Why I Don’t Consume Canola Oil

Ten Reasons Why I Don’t Consume Canola Oil

Canola oil was first developed in the 1970s and celebrated due to its low saturated fat content. In 1995, Monsanto created a genetically modified version, and now, in 2020, 80% of canola plants are grown in Canada are a genetically modified to withstand glyphosate (Roundup). In Australia, 90% of canola oil is not genetically modified, which is incredible, but just because a product is made in Australia, does not mean that they use Australian canola oil. Each product will have a statement similar to “Made in Australia from at least 98% Australian ingredients” or “Made in Australia from at least 30% Australian ingredients. It also doesn’t take away from the majority of negative health consequences of canola oil consumption.

Before we dive in, let’s take a slight detour to summarise why we don’t need oils that are low in saturated fat, and should not be afraid to consume grass fed butter, coconut oil, or whole fat dairy if we are so inclined.

The Truth About Saturated Fats

Over the last five decades, saturated fats have been wrongly vilified for causing cardiovascular disease (CVD). Catch up here and here. Although many people continue to criticise saturated fats despite the research, they are incredible natural wholefoods fats. Here’s a quick recap: 

  • Prior to the industrial revolution, saturated fats were the most prominent sources of fat in the human diet and sustained our ancestors for centuries.
  • Saturated fat is a concentrated source of energy and is therefore blood sugar and insulin steadying. These are the keys to energy, satiety, mental clarity, cognition, weight control and reducing your risk of inflammatory diseases, including CVD.
  • In most, dietary cholesterol only raises blood levels by 1-2%, so its effect is only ever going to be mild. The even better news is that saturated fat actually exerts a positive influence on our high density lipoprotein (HDL). The role of HDL is to transport cholesterol away from our arteries and towards the liver, where it may be either excreted or reused. 
  • Our health goal should not be low cholesterol. Cholesterol provides the building blocks for our cell membranes and hormones, and acts as a carrier for our fat-soluble vitamins A, D, E and K. It is essential to human life – 25% of cholesterol found in the body is located in the brain and without it we would die. Our bodies have developed elaborate mechanisms to manufacture it, to make sure we always have enough.

Cooking with Saturated Fats

When an oil is saturated, the molecule has all the hydrogen atoms it can hold. It is therefore considered “saturated” with hydrogen atoms and, as it also has no double bonds (between the individual carbon atoms of the fatty acid chain), it is not impacted by heat, light or oxygen. Because of the chemical structure of saturated fats, they are solid at room temperature. Saturated fats are extremely heat stable and the best cooking oil for high heat such as the frying. Examples include grass fed ghee, grass fed butter, coconut oil and duck fat.

Note:

  1. If you don’t like the taste of coconut oil, you can buy flavour free versions. They do have a higher degree of human interference, but they are still completely natural.
  2. I use extra virgin olive oil for cold use and lower temperatures such as the oven at <180ºC.

Cooking with Canola Oil 

Canola oil (and all vegetables oils for that matter), are unsaturated and are considered polyunsaturated fatty acids (PUFAs), with two or more double bonds in their structure. As such, they are liquid at room temperature and extremely sensitive to heat, light and oxygen. More on this to come. (And even though rice bran oil is known for its’ high smoke point, it’s still quite high in omega-6 PUFAs, and not one I recommend). 

Oils such a canola are extremely damaging to our health. Here are my top ten reasons why I don’t consume canola oil. 

1. Canola oil is chemically processed

Canola seed comes from a modified rapeseed plant and the oil is most often extracted from the seeds using chemical solvents such as hexane. Nowadays, canola seeds are added to the specific machinery with the solvent and boiled, rinsed and extracted.

2. Canola oil is prone to oxidation

As we discussed earlier, canola oil is unstable in structure and sensitive to heat, light and oxygen. If canola oil is left untreated, it quickly becomes rancid and would otherwise become unpalatable. Manufacturers have found a way around this of course. Keep reading. By comparison, saturated fats have naturally high smoke points and shelf lives.

3. Canola oil contains synthetic antioxidants

To prevent canola oil going rancid and to allow it to be cooked at high heat, synthetic antioxidants are added. These include butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and tert-butylhydroquinone (TBHQ). While the amounts found in canola oil are not concerning on their own, in high doses they have been found to be toxic and carcinogenic in animal models. These ingredients are also found in found foods including cereal, cookies and potato chips. The World Health Organisation (WHO) sets limits of 0-0.5 mg/kg, 0-0.3 mg/kg and 0-0.7 mg/kg respectively – limits which can easily be surpassed by those who regularly eat refined foods and consume vegetable oils. 

4. Canola oil has a 2:1 omega-6 to omega-3 

An excess intake of omega-6 PUFAs is strongly supported in the literature to create systemic inflammation, the largest contributor to our Western lifestyle diseases, including CVD, obesity, hypertension, type 2 diabetes mellitus (DM), Alzheimer’s disease, Parkinson’s disease and some cancers. 

5. Canola oil consumption reduces your body’s antioxidant capability

Canola oil has been shown to significantly reduce red blood cell superoxide dismutase, glutathione peroxidase and catalase activities, total cholesterol and low-density lipoprotein cholesterol. This causes lipid perioxidation, where free radicals take electrons from cell membrane lipids, causing cell damage. This causes a free radical chain reaction and more inflammation. And you know what else happens without antioxidants? Early aging.

6. Canola oil consumption may cause early aging

A reduction of antioxidants increases free radical damage or oxidative stress. This accelerates the aging process as antioxidantssuch as vitamin A, C and E are essential to prevent collagen breakdown and reduce systemic inflammation. Long term oxidative stress damages cells, protein and DNA, which further disrupts skin integrity and contributes to the increased production of fine lines and wrinkles.

7. Canola oil consumption causes a loss of insulin sensitivity 

DM involves the overproduction of the reactive oxygen species which affects lysosomal membrane integrity and lysosomal enzymes activity. This study found that canola oil reduces antioxidant status and increases blood lipid concentration, both which are known risk factors for CVD.

While more specific research in humans is required, what is clear is that excessive consumption of omega-6 PUFAs including canola oil, essentially makes your cells deaf to the signal of insulin. This is considered insulin resistance, the precursor to type 2 DM. This is in direct contrast to olive oil, which has been shown to have antidiabetic and antioxidant activities. Now that we know the Western diet is excessively high in both refined sugar and omega-6 PUFAs, it’s crystal clear why we have the ‘diabesity’ epidemic that we do. 

8. Canola oil consumption cause endothelial dysfunction 

The endothelium is a large endocrine organ that play a significant role in homeostatic functions of the body, including blood flow, blood vessel tone, fluid filtration, neutrophil requirements and hormone transport. This study found that a high intake of canola oil over a 10-week period caused early endothelial dysfunction and increased adipose tissue. As it is well known that endothelial abnormalities play a central role in diseases such as DM, CVD, stroke, cancer and infectious viral diseases, maintaining the health of the endothelium is paramount to longevity. 

9. Canola oil consumption causes decreased synaptic integrity

Synapses allow neurons (brain cells) to communicate with both each other and non-neuronal cells. With reduced strength, comes increase risk of decreased memory, neurodegenerative disorders and nervous system dysfunction. Canola oil consumption causes an increase in the ratio of specific insoluble amino acids (Aβ 42/40) that are known to deposit in the brain and contribute to the development of Alzheimer’s disease. Furthermore, it is strongly support in the literature that the predominant characteristic of Alzheimer’s disease is a loss of synaptic connectivity combined with decreased density in both the neocortex and hippocampus.

10. Canola oil consumption may reduce longevity

The research here is still in animal models, but the above would indicate that it is highly likely to be true in humans. The two hypotheses being tested are due to the lowered antioxidant status and increased phytosterol content. Canola oil is high in the phytosterol, campesterol, which increases the risk of heart disease when consumed in excess. While you may have been told that plant sterols were “heart healthy” (in a margarine promoting campaign, for example), there is actually no scientific evidence that they have any beneficial effect on lowering CVD risk or overall mortality. Some studies have even shown that a high phytosterol intake can increase CVD risk.

Now, I know you may still be heartbroken to learn that your favourite Meredith’s goat’s feta is marinated in canola oil, but it sure is worth finding an alternative as you can’t unlearn what you now know. Check out Blue Bay Cheese as a great place to start. 

References

Bautista R., Carreón-Torres E., Luna-Luna M, et al. 2014. Early endothelial nitrosylation and increased abdominal adiposity in Wistar rats after long-term consumption of food fried in canola oil. Nutrition, 30, 9, 1055-1060.

Costa CA., Carlos AS., dos Santo A., Monteiro AM., Moura EG., Nascimento-Saba CC. 2011. Abdominal adiposity, insulin and bone quality in young male rats fed a high-fat diet containing soybean or canola oil. Clinics (Sao Paulo, Brazil), 66, 10, 1811-1816. 

Esmaillzadeh A., Azadbakht L. 2008. Home use of vegetable oils, markers of systemic inflammation, and endothelial dysfunction among women. American Journal of Clinical Nutrition, 88, 4, 913-921. 

Glueck CJ., Speirs J., Tracy T., Streicher P., Illig E, Vandegrift J. 1991. Relationships of serum plant sterols (phytosterols) and cholesterol in 595 hypercholesterolemic subjects, and familial aggregation of phytosterols, cholesterol, and premature coronary heart disease in hyperphytosterolemic probands and their first-degree relatives. Metabolism, 40, 8, 842-848.

Kahl R., Kappus H. 1993. Toxikologie der synthetischen Antioxidantien BHA und BHT im Vergleich mit dem natürlichen Antioxidans Vitamin E [Toxicology of the synthetic antioxidants BHA and BHT in comparison with the natural antioxidant vitamin E]. Z Lebensm Unters Forsch, 196, 4, 329-338.

Kahl R., Kappus H. 1993. Toxikologie der synthetischen Antioxidantien BHA und BHT im Vergleich mit dem natürlichen Antioxidans Vitamin E [Toxicology of the synthetic antioxidants BHA and BHT in comparison with the natural antioxidant vitamin E]. Z Lebensm Unters Forsch, 196, 4, 329-338.

Lauretti E., Praticò D. 2017. Effect of canola oil consumption on memory, synapse and neuropathology in the triple transgenic mouse model of Alzheimer’s disease. Scientific Reports, 71, 17134. 

Miettinen TA., Gylling H., Strandberg T., Sarna S. 1998. Baseline serum cholestanol as predictor of recurrent coronary events in subgroup of Scandinavian simvastatin survival study. Finnish 4S Investigators. BMJ (Clinical research ed.), 316, 7138, 1127-1130. 

Papazzo A., Conlan,X., Lexis L., Lewandowski P. 2011. The effect of short-term canola oil ingestion on oxidative stress in the vasculature of stroke-prone spontaneously hypertensive rats. Lipids in Health and Disease, 10, 180. 

Samarji R., Balbaa M. 2014. Anti-diabetic activity of different oils through their effect on arylsulfatases. Journal of Diabetes and Metabolic Disorders, 13, 1, 116. 

Sudhop T., Gottwald BM., von Bergmann K. 2002. Serum plant sterols as a potential risk factor for coronary heart disease. Metabolism, 51, 12, 1519-1521.

Rajaratnam RA., Gylling H., Miettinen TA. 2000. Independent association of serum squalene and noncholesterol sterols with coronary artery disease in postmenopausal women. Journal of the American College of Cardiology, 35, 5, 1185-1191.

Rajendran P., Rengarajan T., Thangavel J., Nishigaki Y., Sakthisekaran D., Sethi G., Nishigaki I. 2013. The vascular endothelium and human diseases. International Journal of Biological Sciences, 9, 10, 1057-1069. 

Ratnayake WMN., Plouffe L., Hollywood R. et al. 2000, Influence of sources of dietary oils on the life span of stroke-prone spontaneously hypertensive rats. Lipids, 35, 409-420.

Wong CK., Botta A., Pither J., Dai B., Gibson W., Ghosh S. 2014. A high fat diet rich in corn oil reduces spontaneous locomotor activity and induces insulin resistance in mice. The Journal of Nutritional Biochemistry, 26, 4, 319-326.



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