Rapeseed Oil: Setting the record straight
Rapeseed oil is the latest food item to get it in the neck from the wellness brigade, many of whom, I will add, do not have nutrition or dietetics degrees.
The endless reels of influencers walking around supermarkets and expressing their disappointment that their favourite overpriced food items contain rapeseed oil, as though it means they’re laden with poison, literally makes me want to combust!
As with most things when it comes to nutrition (it is genuinely 50 shades of grey), there is a lot of controversy surrounding rapeseed oil due to its potential health benefits and risks. So, shall we jump in and chew the fat, pun intended?
What even is rapeseed oil?
Rapeseed oil is derived from the seeds of the Brassica napus plant, a member of the Brassica family (just FYI, kale, the holy grail of wellness, is also from the Brassica family).
This versatile oil is known for its mild flavour, light texture, and high smoke point, making it suitable for various culinary pursuits. It is commonly used in salad dressings, for frying, baking, roasting, and as a general all-purpose cooking oil.
Rapeseed oil is also known as canola oil, and its two names are due to the history of its production. Back in the day, the original rapeseed oil from the bright yellow rapeseed plant was found to be especially high in a compound called erucic acid. In animal studies, this erucic acid was found to have some potentially negative impacts on health in high doses.
In humans, the data is much more complicated for several reasons:
We are complex humans, not lab rats!
Thankfully, we have ethical considerations in our research, which means we can’t just feed humans high doses of erucic acid and see what happens.
We eat a range of foods and food groups in our diet, not just glasses of rapeseed oil or erucic acid, so it’s difficult to know exactly how different foods and ways of eating interact with our complex biology.
Complexities aside, back in the day, Canadian scientists innovated a genetically modified rapeseed to reduce the erucic acid content, as well as the glucosinolates (which gave it a bitter taste). The result was a low erucic acid oil with a more palatable flavour. The new creation was named canola oil, a combination of "Canadian" and "ola," which means oil.
Today, most rapeseed used for food is virtually free from erucic acid and is subject to legislation so that it does not exceed 2% (Food Standards Agency [FSA], 2022). The European Food Safety Authority (EFSA) has also established tolerable daily intake levels, and a recent study testing the levels of erucic acid in commercially available rapeseed oils from supermarket shelves found they all met the legal requirements (NCBI, 2022).
In supermarkets or on food packaging today, you will see canola oil, rapeseed oil, and cold-pressed rapeseed oil, which all describe similar things. Canola is more often used in the US and rapeseed in the UK and Europe. I personally use rapeseed oil.
Cold pressed MUST be better, right?
A gentle reminder that we caution against black-and-white thinking here at Isa Robinson Nutrition…
The key contrast between cold-pressed rapeseed oil and regular rapeseed oil lies in their respective extraction methods. Cold-pressed rapeseed oil is mechanically extracted from rapeseeds without the use of heat or chemicals, preserving its natural flavour, colour, and nutritional attributes. Therefore, it may appeal to those wishing for its dark colour and nutty flavour.
In contrast, regular rapeseed oil, often referred to as "refined" rapeseed oil, undergoes processing involving heat, chemicals, and refining techniques, which serves to enhance its colour and shelf life while reducing flavour and aroma. Therefore, it assumes a milder, neutral taste, making it versatile for cooking.
Cold-pressed varieties will often support small-scale British farmers and brands, whilst also coming at a premium. Factors such as taste preference, bank balance, the way you’ll use the oil (e.g., for a dressing or in cooking), as well as convenience, can be taken into account rather than getting caught up in morality.
What are the nutritional benefits of rapeseed oil?
When it comes to nutrition, rapeseed oil boasts quite the profile. It has the lowest saturated fat content of any oil and the second highest level of monounsaturated fats after olive oil. It also has a high level of ALA (the plant form of Omega-3 fatty acids), which play crucial roles in maintaining heart health, reducing inflammation, and supporting brain function.
The presence of phytosterols in rapeseed oil contributes to lowering cholesterol levels, which can further reduce the risk of cardiovascular diseases.
Additionally, rapeseed oil contains essential fat-soluble vitamins, such as vitamin E, which acts as an antioxidant, and vitamin K, vital for blood clotting and bone health.
Rapeseed oil also has a high smoke point making it favourable for cooking.
What does the research say?
A Systematic Review and Meta-Analysis (the gold standard of research) in 2019 found that consumption of rapeseed oil can decrease triglycerides (fats in the blood) and LDL cholesterol (the bad kind of cholesterol) when consumed longer than 30 days.
In addition, it significantly decreased these markers when compared to sunflower oil and saturated fats (Ghobadi et al, 2019). This is also backed up by more recent studies with one describing rapeseed oil as a “functional food”, that basically sounds like superfood status to me (Schieneck and Iggman, 2021; Shen et al, 2023).
Other studies in humans have indicated that rapeseed oil may improve insulin sensitivity (blood sugar regulation), including in women with PCOS (Lin Lin et al, 2013; Yahay et al, 2021).
So, why is there so much bad press when it comes to Rapeseed oil?
Despite its nutritional advantages, rapeseed oil has faced negative press. We hear the wellness warriors using words like “toxic”, “inflammatory”, “highly processed” and so on and so forth.
Look, I get it, when we’re hear those terms being thrown around it doesn’t exactly wet our appetite. Language can have a BIG impact on our relationship with certain foods and it’s something I am always chatting about with my clients.
Let’s get back to the GREY!
Yes some rapeseed oil may be genetically modified, or processed or contain a very minimal, and importantly “safe” level of euric acid. But that doesn’t mean it’s “bad”. So many of our common foods items these days are be genetically modified and many “processed” foods have an important nutritional value - protein powders and supplements are definitely processed! There’s nothing wrong with this, it’s just aiming to highlight how biases can creep in.
Furthermore, the biggest chat around rapeseed is often around it being inflammatory including resulting in “lipid peroxidation”. This is the sciency term to define a sort of “rusting” of fats which can damage our cells and subsequently result in negative health issues over time. We hear about the benefit of antioxidants which help protect fats from this "rusting" process.
So what does the research say on this?
Well in animal studies, rats fed with oxidized rapeseed oil showed some early signs of liver damage. But here’s the thing, they were fed with already oxidized rapeseed oil! In humans, there is no evidence of adverse inflammatory effects or lipid peroxidation.
In fact, some studies have suggested rapeseed oil may have anti-inflammatory effects in human, mainly attributed to its omega 3 content (De Roos et al, 2005). However, more recent studies suggest that rapeseed oil does not significantly alter inflammatory markers when compared to other dietary fats (Lin et al, 2013). It seems rapeseed oil isn’t so inflammatory at all.
Most importantly, it’s necessary to differentiate between fresh rapeseed oil and oxidized. Oxidization of rapeseed oil can occur when its kept for too long, goes past its sell by date, is exposed to air and light, is heated to high temperatures or excessively reheated for example rapeseed oil that may have been kept for months in an old fashion home fat fryer and reheated and cooled often. To prevent oxidisation always keep your oil stored securely in a cool dry place and chuck them out past their sell by date. And please don’t worry about your favourite crispy restaurant foods, restaurants have regulations on how often they have to replace the oil in the deep fat fryer to prevent oxidisation.
So is there a catch – are you actually telling me rapeseed oil is completely safe?
As human beings, we evolved to eat a range of foods and food groups. This not only helps us to obtain a wide range of nutrients without having to stress ourselves out, it’s also means we are able to enjoy lots of different meals and snacks that come with a helping dose of vitamin P for pleasure.
There is no need to go guzzling down rapeseed oil like it’s the new celery juice, although it would be kind of funny if we started a new trend. But a rapeseed oil in cooking and in some of our favourite food products that help us nourish our bodies in a way that’s enjoyable and convenient like snack bars, sauces, cereal etc are certainly not going to break our health. What’s more, they may even be beneficial.
Moreover, research suggests that stress, including stressing about food is actually going to have a worse impact on our health and metabolic parameters including things like insulin and triglycerides than just eating the darn food.
In conclusion
Please don’t panic about rapeseed oil. When included as part of a balanced diet, it offers several nutritional benefits, including heart-healthy fats and essential vitamins. Concerns and misconceptions surrounding rapeseed oil largely stem from misinformation, usually from those who aren’t qualified.
References
De Roos, N.M., Schouten, E.G. and Katan, M.B., 2005. ‘Consumption of a solid fat rich in lauric acid results in a more favorable serum lipid profile in healthy men and women than consumption of a solid fat rich in trans-fatty acids’. Journal of Nutrition, 135(3), pp. 562-566.
Lin, L., Allemekinders, H., Dansby, A., Campbell, L., Durance-Tod, S., Berger, A. and Jones, P.J., 2013. ‘Evidence of health benefits of canola oil’. Nutrition Reviews, 71(6), pp. 370-385.
NCBI, 2013. ‘Rapeseed oil supplementation causes positive effects on plasma lipid profiles and insulin sensitivity in women with polycystic ovary syndrome’. PCOS. Available at: https://pubmed.ncbi.nlm.nih.gov/23731447/.
NCBI, 2019. ‘Effects of canola oil consumption on lipid profile: A systematic review and meta-analysis of randomized controlled clinical trials’. Journal of the American Heart Association. Available at: https://pubmed.ncbi.nlm.nih.gov/30381009/
NCBI, 2021a. ‘The impact of rapeseed oil fatty acids on the risk of atherosclerosis’. Clinical Interventions in Aging. Available at: https://pubmed.ncbi.nlm.nih.gov/33762150/
NCBI, 2021b. ‘Rapeseed oil in the diet of humans’. International Journal of Food Sciences and Nutrition. Available at: https://pubmed.ncbi.nlm.nih.gov/36839357/
NCBI, 2021c. ‘Effects of dietary rapeseed oil on metabolic parameters in women with polycystic ovary syndrome: A retrospective observational study’. PCOS. Available at: https://pubmed.ncbi.nlm.nih.gov/33514384/.