The Heat’s On: Does the Extraction Process Make Vegetable Oil Harmful?

<h3>Fast Facts</h3> <blockquote> <ul> <li>Any cooking oil that’s derived from a plant – as opposed to animal-derived ones, like lard – is referred to as a vegetable oil. However, most vegetable oils – such as canola, corn, soybean, sunflower, safflower, and grapeseed – are not made from vegetables.</li> <li>Vegetable oils are either extracted by mechanically crushing the seeds of plants, like with avocado and olive oil, or by using industrialized chemical solvents (e.g., hexane), like with canola oil and sunflower oil.</li> <li>Hexane is a chemical compound made from crude oil that is commonly used as a chemical solvent to extract oils from plants. Hexane is added to the crushed plant parts and then briefly heated, which causes a chemical reaction, allowing the oil from the plant to separate out. </li> <li>Vegetable oil is found in almost everything – they’re in nearly all processed and packaged foods, such as chips, crackers, pre-packaged baked goods, store-bought salad dressings and condiments, fried foods, non-dairy milks, and even healthy snack foods.</li> </ul> </blockquote> <p>Hop on any social media platform – Twitter, Instagram, TikTok, YouTube, etc. – and you’ll surely see Tweets, Reels, Threads, TikToks, and Shorts about the evils of vegetable oil, also commonly referred to as seed oil. These platforms are full of posts and memes claiming that vegetable oils – such as canola oil, corn oil, soybean oil, sunflower oil, safflower oil, grapeseed oil, rice bran oil, and cottonseed oil – are “toxic” or “poisonous.”</p> <p>Fitness influencers and social media “experts” have even dubbed this group of vegetable oils “the hateful eight,” claiming they can cause inflammation, brain fog, headaches, gut issues, obesity, heart disease, type 2 diabetes, dementia, and many other health problems.</p> <p>There are a few arguments against vegetable oils that have been circulating. The first is that the high amount of omega-6 fatty acids (linoleic acid) in vegetable oils can cause inflammation. The second is that the unbalanced omega-3 to omega-6 ratio in vegetable oils can lead to heart disease. These arguments do have merit and were discussed in a previous article, but this article will focus on a third argument; that the extraction and refining processes of these vegetable oils causes the oils to go rancid and become toxic, making them unsafe to cook with. </p> <p>Read on as we dive into the science and set the record straight about whether the extraction and refining processes do, in fact, make vegetable oils unsafe and unhealthy to consume. </p> <h2>‘Vegetable oils’ – but where are the vegetables? </h2> <p>While they’re called vegetable oils, it may surprise you to know that most vegetable oils are not made from vegetables. Yup, vegetable oil is a bit of a misnomer.</p> <p>Turns out that any cooking oil derived from a plant – as opposed to animal-derived ones, like lard – is referred to as a vegetable oil. By design, vegetable oils are odorless, flavorless, and nearly colorless.</p> <figure><img alt="Vegetable Oil is Soybean Oil | Source: United Soybean Board/Wikimedia" class="img-responsive" src="https://cdn.storymd.com/optimized/RA81JVF9o9/thumbnail.jpg" /> <figcaption>Vegetable Oil is Soybean Oil. <em>Source: United Soybean Board/Wikimedia</em></figcaption> </figure> <p>Like most people, you likely have at least one or more vegetable oils in your kitchen pantry that you use to cook with. They’re relatively inexpensive, found in any grocery store, and most have a high smoke point – meaning they can withstand high temperatures before burning and smoking, which can leave behind an acrid, burnt flavor. Everything you would want in a cooking oil, right? </p> <p>Well, maybe. Maybe not. </p> <h2>Why do vegetable oils get so much hate? </h2> <p>Most cooking oils that are found in your kitchen are produced from seeds, nuts, fruits, or grains. They are either extracted by mechanically crushing the seeds of the plants, like with avocado oil and olive oil, or by using industrialized chemical solvents (e.g., hexane), like with canola oil, sunflower oil, and the rest of the hateful eight. Once extracted, oils are often purified, refined, and sometimes chemically altered. </p> <p>And therein lies the problem – the extraction and refining processes of various cooking oils.</p> <p>Take a scroll on TikTok or Instagram and you’ll see a line-up of social media health “experts” and fitness influencers encouraging their followers to stick with avocado oil and olive oil because they’re extracted by simply crushing the seeds, a seemingly “natural” process. This, of course, also means that these influencers are steering people away from consuming “the hateful eight” vegetable oils. They believe that oils that are refined and chemically extracted and altered contain pro-inflammatory and toxic properties, which can increase the risk of developing certain health conditions, such as inflammation, gut issues, obesity, type 2 diabetes, hypertension, heart disease, dementia, and more. </p> <p>Let’s walk through these arguments to see if they hold any water – or oil. </p> <h3>Argument #1: The use of chemical solvents, such as hexane, for vegetable oil extraction makes it unsafe for health </h3> <p>To make vegetable oil from plants, first the plant parts that are used to make the oil are harvested, deshelled, hulled, and cleaned. If the seed is used to make the oil, it is crushed or broken up into smaller pieces. These pieces are then heated before adding chemical solvents, such as hexane, to extract the oil. </p> <p>Hexane is a chemical compound made from crude oil, and yes, it is commonly used as a chemical solvent to extract oils from plants – for almost a century now, in fact. During extraction, hexane is added to the crushed plant parts and then briefly heated, which causes a chemical reaction to allow the oil from the plant to separate out. The heat also causes hexane to evaporate, but sometimes, some trace amounts can remain. </p> <figure><img alt="Hexane 3D ball | Source: Jynto (talk)/Wikimedia" class="img-responsive" src="https://cdn.storymd.com/optimized/pA7xE2Clo9/thumbnail.png" /> <figcaption>Hexane. <em>Source: Jynto (talk)/Wikimedia</em></figcaption> </figure> <p>Studies have shown that exposure to hexane in large quantities – whether by ingesting or inhaling it – may cause toxicity in the brain (neurotoxicity). But the trace amounts found in vegetable oil is nowhere near enough to cause toxicity. In fact, studies show that the amount of leftover hexane – if there’s any at all – is less than one millionth of a milligram per kilogram of oil, a negligible amount. </p> <p>To put that into perspective, you’re exposed to much more hexane by inhaling gasoline fumes from cars in a day than you are from consuming vegetable oil. That’s not to instil more fear about hexane exposure. Rather, it’s to highlight the point that any residual hexane found in vegetable oil is not a health concern, and current research shows no evidence of any adverse health effects from consuming trace amounts.</p> <p>If hexane exposure is still something you’re worried about, skip the oils that use hexane in their extraction process (canola oil, corn oil, soybean oil, sunflower oil, safflower oil, grapeseed oil, rice bran oil, and cottonseed oil) and stick to using olive oil, avocado oil, or coconut oil. </p> <figure><img alt="Oil, Olive Oil, Bottles | Source: Pezibear/Pixabay" class="img-responsive" src="https://cdn.storymd.com/optimized/WdxBK5UeA2/thumbnail.jpg" /> <figcaption>Olive Oil. <em>Source: Pezibear/Pixabay</em></figcaption> </figure> <h3>Argument #2: The refining of vegetable oils causes them to go rancid</h3> <p>The truth is most vegetable oils stocked on the shelves of grocery stores – meaning the hateful eight oils – undergo some sort of refining process. Typically, once the oil is extracted, it’s then bleached using bleaching clay – not the bleach you use to make your clothes white – to remove any dark coloring. It’s then deodorized to remove any odor, and is then filtered to remove any residual solvents, leaving the oil in its final state, which is packaged and sold. </p> <p>The refining process gives vegetable oil its light color, makes it flavorless and odorless, and makes it more stable with a longer shelf life. The claim that refining vegetable oil makes it more likely to go rancid is untrue. In fact, refining vegetable oil reduces the likelihood of rancidity. </p> <h3>Argument #3: The refining of vegetable oils makes them toxic due to the chemical solvents and high heat used</h3> <p>What about the claims that the refining process makes vegetable oil toxic because of the heating and use of solvents to clean, bleach, deodorize, and filter the oil? Well, yes, certain vegetable oils – like canola oil, grapeseed oil, sunflower oil, or any of “the hateful eight” oils – do produce harmful compounds, such as acrylamide, when heated beyond their smoke point, which is the point at which they start to burn. Acrylamide is a chemical that is formed in some foods during high-temperature cooking processes, such as deep frying, roasting, and baking. Studies show that high levels of acrylamide can increase the risk of various cancers. </p> <p>So, while, yes, burning vegetable oil can cause acrylamide to form, most vegetable oils – specifically “the hateful eight” – have the highest smoke point of any oil. It takes much higher temperatures – over 500 degrees Fahrenheit or 260 degrees Celsius, which is a higher temperature than you’d generally use to cook – for these oils to become threatening or harmful to your health. Additionally, studies show that these oils must be heated for multiple hours at their smoke point to produce quantities high enough to be detrimental to your health.</p> <p>On the flipside, unrefined, highly flavorful oils – such as flaxseed oil, walnut oil, extra-virgin olive oil, and others – while they may be “healthier” because they undergo a cold-pressed, mechanical crushing extraction process free from chemical solvents and high heat, they are actually less stable, and have a lower smoke point. They are therefore easier to burn and will produce those harmful, toxic compounds (e.g., acrylamide) when heated to their lower smoke point. </p> <p>That’s not to say that these “healthier” seed and nut oils are toxic – they aren’t. But rather, how you intend to use the oil matters. Cooking oils need to be used appropriately to ensure they don’t take on a bitter taste, go rancid, or become toxic. So, if you’re frying food, using vegetable oils like canola, sunflower, grapeseed, or any other oil with a higher smoke point may actually be healthier for you than olive oil or walnut oil. But, if you’re making a salad dressing, it’s probably best to use an unrefined, flavorful, less stable oil, such as olive oil or avocado oil. </p> <p>Above all else, don’t burn your oils when you’re cooking with them, and you’ll have nothing to worry about. </p> <h2>So, what’s the takeaway? </h2> <p>Looking specifically from the view of extraction and refining, vegetable oils are not inherently bad for you. In fact, there seems to be no evidence to back up the claims that the extraction and refining processes of vegetable oils cause toxicity or that they lead to adverse health effects. </p> <p>In the grand scheme of things, the bad reputation of vegetable oils has more to do with how much Americans consume on a daily basis – especially those who primarily eat a modern American diet. There are also the existing concerns regarding inflammation. Vegetable oils are found in almost everything – they’re in nearly all processed and packaged foods, such as chips, crackers, pre-packaged baked goods, store-bought salad dressings and condiments, fried foods, non-dairy milks, and even healthy snack foods. And because it’s found in everything, vegetable oils – while nearly nonexistent a hundred years ago – now account for 20% of Americans’ calories. </p> <figure><img alt="Processed Foods | Source: TheVisualMD" class="img-responsive" src="https://cdn.storymd.com/optimized/Nq4NQLs7oK/thumbnail.jpg" /> <figcaption>Processed Foods. <em>Source: TheVisualMD</em></figcaption> </figure> <p>On top of that, most restaurants use vegetable oil as their cooking oil of choice. So, if restaurants are not filtering and changing their frying oil frequently, there may be more buildup of harmful compounds, like acrylamide, in the oil. If you’re eating out several times a week, you may be accumulating acrylamide in your body, which can have harmful effects. </p> <p>If you’re concerned about consuming vegetable oils, limit the amount of processed and packaged foods you eat and skip the fried foods when eating out at restaurants. </p> <p>The decision of whether to consume vegetable oils is a personal choice and should be made on the best available evidence – not what social media “experts” or fitness influencers say.</p> <h2>More on Fats & Oils</h2><ul><li><a href="https://soulivity.storymd.com/journal/m9zxbra0gw-wellness-and-nutrition-fats" target="_blank">The Truth About Fats</a></li><li><a href="https://soulivity.storymd.com/journal/4m8gyv5hpw-dietary-fats" target="_blank">Dietary Fats</a></li><li><a href="https://soulivity.storymd.com/journal/wgoeexoc4j-omega-3-fatty-acids" target="_blank">Omega-3 Fatty Acids: Recommended Intake, Sources, Benefits, Deficiency</a></li></ul>