Is Canola Oil Bad for You? Dietitian Review

Is canola oil Bad for you? There’s so much conflicting information available online about seed oils. Some say it’s beneficial for health, while others claim it’s toxic. We’ve reviewed the current research on canola oil to help you make an informed choice about whether or not to add it to your grocery cart.

Where does canola oil come from?

Canola oil comes from plants belonging to the Brassica napus B. rapa or B. juncea species. This plant is part of the Brassicaceae family, which also includes cabbage, broccoli, and cauliflower. The oil itself comes from the plant seeds which are a rich source of monounsaturated fats, with oil making up 45% of the seed’s volume (1).

How is canola oil made?

There are seven steps in the production of canola oil (1): 

1. Harvesting: the canola plant is harvested and separated from other weeds or stems picked up during harvesting. 
2. Flaking: the seed is rolled into a flake so that the oil is to extracted more easily. 
3. Cooking: flakes are cooked in a series of drums to help break down the seed. 
4. Pressing: most of the oil is removed by pressing the flakes. Any remaining pieces of flake are then pressed into a cake. 
5. Solvent extraction: the cake is put into an extractor and combined with hexane, a solvent that removes the rest of the oil. Hexane is then removed from the canola oil and reused.
6. Refining: the oil may be refined to improve the colour, flavour, and stability. The oil is also sent through filters to remove any leftover particles. 
7. Steaming: the oil is steamed to remove unpleasant odours or compounds.

Note: a small percentage of canola oil is extracted from seeds without chemical solvents (hexane) or heat. These methods are called double press, expeller press, or cold press, and can help retain the antioxidant content in the oil (1, 8). 

Is canola oil beneficial for heart health?

Canola oil supporters most often tout its fat profile and potential benefits in cardiovascular disease prevention.

Canola oil is high in unsaturated fats, particularly oleic acid, a monounsaturated fat. Specifically, monounsaturated fats make up 62% of the total fats in canola oil, followed by linoleic acid (omega-6) at 19%, alpha-linoleic acid (omega-3) at 9%, and saturated fat at 7% (1).

Even the largest heart health authorities, such as the American Heart Association and Heart and Stroke Foundation of Canada, recommend canola oil as a “better-for-you oil”. This is due to the high amount of monounsaturated fats and low amount of saturated fats. But does this fat profile translate to improving health outcomes? Here’s what we found in the research:

Canola oil and cholesterol (compared to saturated fat intake)

Canola oil has been heavily researched over recent decades. Research has found that canola oil may have a beneficial effect on lowering cholesterol levels, though this effect depends on the overall diet profile. When canola oil replaces saturated fats in the diet, this can result in a reduction in total cholesterol levels, LDL levels (often referred to as “bad” cholesterol), and cholesterol ratio (2, 3, 13).

Researchers estimate that this reduction in cholesterol translates to as much as a 20-40% reduced risk of cardiovascular disease. However, there is a more significant reduction in those with higher baseline cholesterol levels. Research has not found a consistent impact of canola oil on HDL levels  (often referred to as “good” cholesterol) or triglycerides (2,3, 13).

Canola oil and cholesterol (compared to other vegetable oil use)

While these reviews seem to show that choosing canola oil over cooking oils containing saturated fat, such as butter, is beneficial, the benefit of canola oil over other vegetable oils, such as olive oil and sunflower oil, is less clear. Some studies show that canola oil use results in lower LDL and total cholesterol levels than sunflower or olive oil use. However, researchers note that these studies are small and often of low quality (2, 3).

In summary, more research is needed to determine if there are health benefits to using canola oil over other vegetable oils.

Does canola oil cause inflammation?

Canola oil fatty acid profile and inflammation

Those against canola oil often claim that it will increase inflammation. Inflammation has become a buzzword in the wellness community, and a common topic fuelled by misinformation. Here’s what we know about chronic inflammation: traditional ‘Western’ dietary patterns can lead to chronic inflammation, which increases the risk of some diseases such as type 2 diabetes, cardiovascular disease, and cancer (4).

Western diets can be pro-inflammatory partly due to the high omega-6 content of the diet (5), with vegetable oils being a significant source of omega-6. However, not all vegetable oils are created equal. Canola oil contains only 19% omega-6 fatty acids, compared to corn oil, which contains 53% omega-6 fatty acids.

Does canola oil cause inflammation as a processed oil?

Another reason why canola oil has been associated with inflammation is due to it being a processed oil. This is a fair assumption, but here’s what the research shows:

A recent randomized control trial investigating biomarkers of cardiovascular disease showed no changes in oxidative stress or inflammatory markers between canola oil, sunflower oil, and control diet (6). A recent review article investigating risk factors of cardiovascular disease also showed no difference in inflammatory markers with canola oil use compared to olive oil and sunflower oil. However, there may be some benefits to reducing LDL oxidation (note: when LDL is oxidized it becomes pro-inflammatory) with canola oil use over saturated fats (4).

Nordic diet and inflammation

Researchers have also investigated the Nordic dietary pattern and associated inflammatory markers. A Nordic diet is similar to a Mediterranean diet as it is rich in whole grains, fruit, vegetables, and fish and low in red meat, dairy, and processed foods. However, the Nordic diet differs from the Mediterranean diet in that canola oil is the primary oil instead of olive oil. A recent review of the Nordic diet and low-grade inflammation found that adherence to a Nordic diet pattern was inversely associated with CRP levels (a marker of inflammation), and appears to reduce levels of inflammation. Though, this is based on very few studies that are small in size (12).

Does canola oil contain hexane?

Those against canola oil also note concerns with the solvent hexane used in its processing. Hexane is a chemical used as a solvent for the extraction of vegetable oils from seeds and crops (7). As mentioned previously, hexane is involved in step 5 of the process of extracting canola oil from the seed. Most of the hexane is removed in a later step in canola oil extraction (1). It’s difficult to assess the amount of hexane remaining in the end product of canola oil, as further processing methods can break down hexane (7).

There is some concern that high levels of exposure to hexane may cause toxicity and negative effects on health. However, it’s important to remember that our overall exposure to hexane in a typical diet is very low. Our population’s estimated intake of Hexane from vegetable oils is estimated at 0.70g/kg body weight per day. Health Canada has determined that 189mg/kg body weight of hexane per day is needed to cause harm (7).

Summary: 

So, TL;DR: while significant exposure to hexane is concerning, the amount of hexane found in vegetable oils, and our overall diet, is very low. However, it’s understandable that even trace amounts of a chemical in food may not sit well with consumers. If you’re looking for an alternative, cold-pressed canola oil (or alternative) is available which does not utilize solvents as part of its processing.

What is the smoke point of canola oil?

The smoke point of an oil is the temperature that the oil will start to break down and potentially produce volatile compounds (10).

The smoke point of canola oil is 238C (460F), meaning it is safe for cooking up to this temperature. To compare this to other vegetable oils, the smoke point of extra virgin olive oil is 195C (383F), safflower oil is 212C (413F), and avocado oil is 271C (519F) (1, 10).

Canola oil is a source of oleic acid, which is more heat-stable than other unsaturated fatty acids. The heat stability makes canola oil a desirable choice for cooking. Another factor that increases the smoke point of an oil is its antioxidant content. Canola oil is generally rich in antioxidants, even more so when produced using cold-press methods (1, 10, 11).

Is canola oil bad for you?

No, canola oil in moderation is not bad for you. Canola oil is rich in monounsaturated fats and may reduce your risk of cardiovascular disease. Despite being a processed oil, research does not show that it increases inflammatory markers in the body. Trace amounts of the chemical hexane may be present in most conventionally produced canola oil, but the amount is likely too low to cause harm. As an alternative, cold-pressed canola oil is made without the use of chemical solvents.

Bottomline: 

Whether or not canola oil is a better option than other vegetable oils, such as olive oil, remains unknown. What we do know is that when it comes to your fat intake, the overall fat profile of your diet is more important for your health than whether or not you include one single fat source. This means that consuming a variety of fat sources in your diet, such as nuts, seeds, avocados, fatty fish, and oils, is best to ensure that you have a variety of unsaturated fatty acids in your diet to support your health.

More Ingredient Reviews

Lecithin 

Lecithins are naturally present in some foods and play an important role as an ingredient in processed foods. Lecithins are recognized as safe by Health Canada and the FDA, and the amount typically found in food products is very low. Read our full Lecithin Ingredient review here.

Natural Flavours 

A natural flavour is any component, such as an essence, or oil, extracted from a plant or animal product through the processing of that plant or animal product. We recommend consuming less processed foods as a whole, but if you see natural flavours on the ingredient list of your favourite food package, no need to worry. Read more about natural flavours here.

Sources:

1. Canola Council of Canada https://www.canolacouncil.org/
2. Lin L, Allemekinders H, Dansby A, Campbell L, Durance-Tod S, Berger A, Jones PJ. Evidence of health benefits of canola oil. Nutr Rev. 2013 Jun;71(6):370-85. doi: 10.1111/nure.12033. Epub 2013 May 2. PMID: 23731447; PMCID: PMC3746113.
3. The Effects of Canola oil on CVD Risk factors: a systematic review and meta-analysis with dose-response analysis of controlled clinical trials. Amiri, M. et al. 2020. Nutrition, Metabolism & Cardiovascular Disease (2020) 30, 2133-2145. https://pubmed.ncbi.nlm.nih.gov/33127255/
4. Aleksandrova K, Koelman L, Rodrigues CE. Dietary patterns and biomarkers of oxidative stress and inflammation: A systematic review of observational and intervention studies. Redox Biol. 2021 Jun;42:101869. doi: 10.1016/j.redox.2021.101869. Epub 2021 Jan 22. PMID: 33541846
5. DiNicolantonio JJ, O’Keefe JH. Importance of maintaining a low omega-6/omega-3 ratio for reducing inflammation. Open Heart. 2018 Nov 26;5(2):e000946. doi: 10.1136/openhrt-2018-000946. PMID: 30564378.
6. Nicol, K., Mansoorian, B., Latosinska, A., Koutroulaki, A., Mullen, B., & Combet, E. (2022). No evidence of differential impact of sunflower and rapeseed oil on biomarkers of coronary artery disease or chronic kidney disease in healthy adults with overweight and obesity: result from a randomised control trial. European Journal of Nutrition, 61(6), 3119–3133. https://doi.org/10.1007/s00394-022-02810-5
7. Screening Assessment for the Challenge Hexane. Environment Canada (2009)
8. Chew SC. Cold-pressed rapeseed (Brassica napus) oil: Chemistry and functionality. Food Res Int. 2020 May;131:108997. doi: 10.1016/j.foodres.2020.108997. Epub 2020 Jan 12. PMID: 32247493.

9. The Biology of Brassica napus L. (Canola/Rapeseed). Plant and Biotechnology Risk Assessment Unit, Plant Health Science Division, Canadian Food Inspection Agency, Ottawa, Ontario.

10. Katragadda, H. R., Fullana, A., Sidhu, S., & Carbonell-Barrachina, Á. A. (2010). Emissions of volatile aldehydes from heated cooking oils. Food Chemistry, 120(1), 59–65. https://doi.org/10.1016/j.foodchem.2009.09.070

11. Gunstone FD. Vegetable Oils in Food Technology: Composition, Properties and Uses. Wiley‐Blackwell; 2011.
12. Lankinen M, Uusitupa M, Schwab U. Nordic Diet and Inflammation-A Review of Observational and Intervention Studies. Nutrients. 2019 Jun 18;11(6):1369. doi: 10.3390/nu11061369. PMID: 31216678
13. Ghobadi S, Hassanzadeh-Rostami Z, Mohammadian F, Zare M, Faghih S. Effects of Canola Oil Consumption on Lipid Profile: A Systematic Review and Meta-Analysis of Randomized Controlled Clinical Trials. J Am Coll Nutr. 2019 Feb;38(2):185-196. doi: 10.1080/07315724.2018.1475270. Epub 2018 Oct 31. PMID: 30381009.