‘If you’re about to cook with seed oil, stop right now. I’m going to transform how you see your health and your kitchen. Keep watching to find out how.’
Scene: A man in his 30s, clean-cut with a calm intensity, strides down a supermarket aisle in a dark denim jacket and sneakers. He stops in front of the shelves, reaching for a bottle of sunflower oil. He turns to face a camera, brandishing the bottle and issues a dire warning.
‘Seed oils are for greasing engines not cooking.’
If you use social media frequently, this scenario will not be strange to you. Reels, shorts and podcasts abound, each with a single purpose: to convince you to ditch seed oils – immediately.
What They Say
Intellectually, they (seed oils) are bad. Biochemically, they are really, really bad.
—Mary Ruddick.
I strongly believe seed oils are one of the greatest drivers of chronic diseases today.
—Paul Saladino (a self-proclaimed carnivore MD with over 2.5 million followers on Instagram)
Claims that seed oils, derived from rape seed (canola), soybeans, sunflower seeds, etc. can lead to serious medical conditions are all over online health spaces right now. You might have seen wellness influencers like Dr David Jockers and Dave Asprey, using their platforms to denounce these kitchen staples. Self-styled TikTok experts and Instagram fitness gurus are eager to tell their millions of followers that seed oils are ultra-processed agricultural by-products. That there has been an increase in ailments such as inflammation and heart disease and seed oil is to blame.
Are these influencers on the right side of the facts or are they spreading misinformation to their huge audience on behalf of big butter?
What are seed oils?
If we want to make an informed decision about whether to eat seed oils, we have to start with what they are and where they come from and how we get them.
Ancient oils, new advances
Seed oils are edible fats extracted from various plant seeds. Some examples include grapeseed, sunflower, canola, corn and soybean oils.
While some of these oils have traditionally been used in cooking, such as oil collected from crushed sunflower seeds, others, for example canola oil, have only gained gastronomic popularity in the last hundred years. Before the 20th century, canola oil was used to power lamps and for handicrafts because it was difficult to produce. It also smelled like cabbage and tasted pretty bad. Advances in crop development, chemical engineering and food science have helped seed oil makers to find ways to improve the flavour of the oil and to increase yields.
Safe cooking oil supplies are essential for food security. With a global population exceeding eight billion people, producing sufficient plant-based food for everybody just isn’t possible with pre-industrial agricultural techniques. Where once we relied on resource-intensive animal by-products, nuts and fruit oils for our food, now we can also extract useful fats from plant parts that would otherwise be discarded. Today, seed oils in their liquid form are widely used for baking goods, salad dressings, margarine and chips.
How Are Seed Oils Extracted?
Seed oils are extracted through two different methods
- Mechanical Extraction:
This is based on traditional methods of collecting oil from plants, for example olive oil, peanut oil, sunflower oil and linseed oil. People would grind or crush the plant material and then separate the oil from the resulting pulp. These days, seed oils are often extracted using a screw press method, which involves crushing the seeds and slightly heating them to reduce their moisture content.
This technique is widely used for industrial and commercial purposes, but it can only extract 45% oil content from the seeds.
- Solvent Extraction:
Large-scale oil production uses a solvent to extract the oils. Producers wash flaked seeds in a solvent that allows the oils to dissolve and seep out into a vat. This method extracts 100% of the oils, and the end product is of significantly better quality than those generated through mechanical crushing.
After extraction the seed oil will contain impurities and residual solvents. These are removed via a refining process that cleans them up and improves their overall quality. Commonly used solvents include methanol, hexane and heptane. All three of these have a lower boiling temperature than seed oil. Once the extraction phase is finished, the seed oil and solvent mix are heated to boil off the solvent. The workers distill the evaporated solvents from the mixture so that they can reuse these expensive materials. Because the solvents have a low boiling temperature, as long as the oil is uniformly heated to over 70 degrees Celsius for a sufficient time, all the solvent will turn to gas and be drawn off. The European Union has set a maximum residual limit of 1 mg/kg of hexane in our cooking oil. To put that in perspective, that’s a ratio of one part hexane to a million parts oil. The oil is not heated to a high temperature that would change the oil’s properties or make it unsafe to eat. Usually 120 degrees C is the upper limit used for extraction and solvent removal. We use temperatures above this to cook our food.
So should we be worried about the ‘chemicals’ in seed oils? Probably not. Firstly all plant-based foods contain trace contaminants such as heavy metals and microplastics. Plants take up what’s in the soil. If there are metals, pesticides, herbicides or microplastics in the soil, there’s a fair chance they will also be found in any plant growing in it. Even plants with organic certification can absorb whatever is in the soil or water. The seed oil refining system uses materials like water, lye and chelating agents to wash away or trap impurities that occur naturally, through farming methods or during the oil extraction process.
Far from tainting the oils, refining purifies them. The oils are not chemically altered; they are being filtered and cleaned. You could argue that canola oil is less likely to contain contaminants than artisan-made olive oil.
What’s in Seed Oils?
Seed oils are primarily composed of polyunsaturated fatty acids (PUFAs), which are liquid at room temperature and are widely recognized for their benefits to the heart. Some of them include:
- Omega-6 fatty acids, mainly linoleic acid
- Small amounts of omega-3 fatty acids, depending on the source
Other components of seed oils include:
- Vitamin E (tocopherols) in some oils
- Phospholipids
Polyunsaturated Fatty Acids are Essential
Polyunsaturated fatty acids or PUFAs are essential nutrients that our bodies cannot produce on their own; rather we acquire them through everyday foods like sunflower oil, walnuts, flaxseed and fatty fish like salmon or sardines.
A 2025 study highlights some reasons why PUFAs are good for you:
- They build cell membranes, support brain development, keep your skin healthy and even help your body manage inflammation.
- They help protect your heart. When you eat less saturated fat (like butter, red meat, and palm oil) and instead use oils rich in PUFAs, your body manufactures less ‘bad’ LDL cholesterol, which decreases your risk of heart attacks and strokes.
- They help with memory and learning, helping the brain to function well. PUFAs are especially important during pregnancy and early childhood when the brain is developing quickly.
- They can help reduce fat buildup, improve insulin sensitivity and lower certain hormones linked to weight gain and inflammation. Altogether, consuming PUFAs leads to better metabolic health as we age because they manage how our body stores and burns fat.
Guy Johnson, an adjunct professor of food and human nutrition at the University of Illinois Urbana-Champaign and Kevin Fritsche, a professor of animal science and nutrition at the University of Missouri, conducted a systematic review of 15 clinical trials that were carried out between 1993 and 2008 and studied about 500 adults and there was no clear evidence linking the consumption of linoleic acid (the main omega-6 fatty acid in seed oils) to inflammation. Recent research further indicates that polyunsaturated fats, including those found in seed oils, can reduce oxidative stress levels and improve heart health. Evidence also abounds from randomized controlled trials showing that replacing saturated fats with polyunsaturated fats in the diet helps to lower cholesterol levels and reduce the risk of heart disease by as much as 10%.
Are Seed Oils Harmful?
Critics’ Concerns:
So why are people so worked up about seed oils? The anti-seed oil messaging generally falls into two camps:
- Many critics of seed oils raise concerns about the industrial methods deployed to extract them. They point to the use of chemical solvents and high-heat processing, along with the highly refined and ultra-processed nature of these oils, as a potential health risk, especially when consumed on a regular basis. Some studies suggest that these oxidized oils can increase oxidative stress, a process that damages cells and may contribute to cardiovascular disease. On the other hand, if we look at the facts, the chemical solvents are removed and reused by the cooking oil producers, and heat processing doesn’t involve temperatures in excess of those we use every day for frying, baking, roasting, etc. so perhaps these aren’t so concerning after all?
Some of these worries can be traced back to the adverse health effects of partially hydrogenated oils. Once bitten, twice shy, as the adage goes, it’s unsurprising then that people would be wary about industrial influences on food oil. The answer is to get more information.
- Other seed oil detractors are concerned about the innate qualities of the seed oils themselves. These critics believe that certain polyunsaturated fats found in seed oils trigger inflammation.
The abundance of omega-6 fatty acids in seed oils, they say, promotes inflammation, contributing to conditions like heart disease, diabetes and arthritis.
The Truth
So what’s the truth? To find out, we need to ask three key questions:
- Are rates of heart disease going up?
The answer is ‘Yes’. A descriptive epidemiological study comprising data across 204 countries showed that heart disease remains the leading cause of death worldwide, accounting for approximately 20.5 million deaths in 2021, which was nearly a third of all global deaths. The study attributed this steady rise in heart disease to a variety of factors, including high systolic blood pressure, poor diet, diabetes and air pollution. The unequal distribution of resources has led to declines in rates of heart disease in high-income countries, while others face rapid increases.
- Are Seed oils to blame for the increase in heart disease or chronic inflammation?
The answer is ‘No’. Our bodies can’t make omega-3 and omega-6 fatty acids; they are essential nutrients, meaning we can only get them through our diet. We consume more omega-6 than omega-3 and that difference has made some critics speculate that it is unhealthy based on the relative proportions.
Rather than following strict rations, eating a balanced diet helps us to maintain our body system. Our consumption of ultra-processed foods has increased, and with it, obesity rates. These foods contain seed oils, but they also contain large quantities of sugar, salt and refined carbohydrates. Eating foods packed with all of these elements increases our risk of chronic diseases and Metabolic Syndrome.
Seed oils are an easy scapegoat because we can tell ourselves that by switching to ultra-processed foods containing animal fats, we can avoid making less appealing changes to our diet. Seed oils alone are not to blame for any increase in inflammation or heart disease.
- Are people who eat seed oils less healthy than people who eat other kinds of oils?
The answer is No. A review of 38 studies and 811,000 participants found that the consumption of linoleic acid, which is a major component of seed oils, reduced the risk of death from heart disease, type 2 diabetes and even cancer. This provides science-backed evidence that people who consume more seed oils live a healthier life. Another review study published in 2019 also examined 30 unique studies that had 68,000 participants also showed the same reduced risk of heart disease death due to higher levels of linoleic acid.
What Do Official Health Authorities Say?
In addition to the copious scientific evidence showing that seed oils are safe, government health bodies have also reviewed the relative safety of seed oils.
- The World Health Organization reported that over 250, 000 people die annually from consuming trans fat – produced by the partial hydrogenation of liquid oils – and recommended their ban and replacement with polyunsaturated fats like those found in sunflower oil, corn oil and other seed oils.
- The U.S. Food and Drug Administration (FDA) in 2018 concluded that consuming oleic acid (found in sunflower oil, corn oil and others) can reduce the risk of coronary heart disease. Although there is no authorized health claim on seed oils from the FDA, they have issued qualified claims supported by credible scientific evidence highlighting that seed oils are healthy and safe for consumption.
- The American Heart Association (AHA) has consistently encouraged replacing bad fat (trans fat) with good fat (monounsaturated and polyunsaturated) found in seed oils. Some of these oils are name checked – corn oil, soybean oil, sunflower oil – as healthy cooking oil choices that you should consider.
- The European Food Safety Authority (EFSA) has carried out a variety of tests and assessments on different seed oils to confirm if they are harmful or not. The general verdict has been that, under certain conditions, some seed oils (like Allanblackia seed oil) are safe for consumption, while for other seed oils (like rapeseed oil), there is currently no conclusive safety evidence and further studies might be needed.
Learning From History
Seed oils rapidly gained prominence in the food industry in the early 1900s after Procter & Gamble discovered that adding hydrogen atoms to liquid cottonseed oils could raise its melting temperature, solidifying it at room temperature. This property made partially hydrogenated seed oils an ideal replacement for expensive and ‘unhealthy’ saturated fats such as shortening, butter or dripping. Early nutritional research had concluded that saturated fats were ‘bad’, making partially hydrogenated ‘healthy’ oils, AKA trans fats, an attractive alternative. These newly invented oils became the basis of many animal fat substitutes in margarine, baked goods and a variety of crispy snacks.
In the century since hydrogenated oils were introduced, researchers determined that partially hydrogenated oils or trans fats are not safe for us to eat after all, and as a result some countries, including the USA and Canada, have banned their sale for use in food.
Seed oils and partially hydrogenated seed oils are not interchangeable. Adding those hydrogen atoms to seed oil causes a chemical change that alters the way that our body processes them.
Seed Oils in Everyday Cooking
Seed oils can be used for cooking, baking and other culinary activities, but the fatty acids contained in the oils are less stable at high temperatures. This means that they can break down into compounds that may be harmful to our body, especially when they are overheated or reused several times.
So, when you want to cook using seed oils or any oil at all, remember to put it on moderate heat and avoid reusing the oils to prevent harmful chemicals from being released.
Are Seed Oils Safe?
Considering the scientific evidence, seed oils are safe for consumption.
They contain essential PUFAs, such as omega-6, which your body needs. No, they don’t cause inflammation in healthy people ,as shown in a review of 15 controlled trials. What’s more, a meta-analysis of 13 cohort studies demonstrated that you’re not quietly damaging your heart or brain when you cook with seed oils.
Trusted organizations like the American Heart Association and the World Health Organization recommend using seed oils in place of saturated fats like butter or coconut oil.
If, however, most of your seed oil intake comes from deep-fried fast food or heavily processed snacks, the issue isn’t the oil; it’s the overall quality of your diet.
At the end of the day, no single ingredient will make or break your health. What really matters is the big picture: eating whole foods, getting a mix of healthy fats, moving your body and staying curious about what goes on your plate.
References
American Heart Association. (n.d.). Healthy cooking oils.https://www.heart.org/en/healthy-living/healthy-eating/eat-smart/fats/healthy-cooking-oils
Dinicolantonio, James & O’Keefe, James. (2018). Omega-6 vegetable oils as a driver of coronary heart disease: The oxidized linoleic acid hypothesis. Open Heart. 5. e000898. 10.1136/openhrt-2018-000898.
European Food Safety Authority (EFSA). (2018). Scientific opinion on the Tolerable Upper Intake Level for vitamin D. EFSA Journal, 16(7), 5362. https://www.efsa.europa.eu/en/efsajournal/pub/5362
European Food Safety Authority (EFSA). (2023). Safety assessment of the process used to produce recycled PET for food contact materials. EFSA Journal, 21(10), 7706. https://www.efsa.europa.eu/en/efsajournal/pub/7706
Farvid, M. S., & Ding, M., et al. (2014). Dietary linoleic acid and risk of coronary heart disease: A systematic review and meta-analysis of prospective cohort studies. Circulation, 130(18), 1568–1578. https://doi.org/10.1161/CIRCULATIONAHA.114.010236
Hooper, L. et al. (2020). Reduction in saturated fat intake for cardiovascular disease. Cochrane Database of Systematic Reviews, 2020(5), CD011737. https://doi.org/10.1002/14651858.CD011737.pub2
Innes, J. K., & Calder, P. C. (2018). Omega-6 fatty acids and inflammation. Prostaglandins, Leukotrienes and Essential Fatty Acids, 132, 41–48. https://doi.org/10.1016/j.plefa.2018.03.004
Johnson, G. H., & Fritsche, K. (2012). Effect of dietary linoleic acid on markers of inflammation in healthy persons: A systematic review of randomized controlled trials. Journal of the Academy of Nutrition and Dietetics, 112(7), 1029–1041.e15. https://doi.org/10.1016/j.jand.2012.03.029
Li, J., Guasch-Ferré, M., Li, Y., & Hu, F. B. (2020). Dietary intake and biomarkers of linoleic acid and mortality: Systematic review and meta-analysis of prospective cohort studies. The American Journal of Clinical Nutrition, 112(1), 150–167. https://doi.org/10.1093/ajcn/nqz349
Marklund M et al. Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) Fatty Acids and Outcomes Research Consortium (FORCE). Biomarkers of Dietary Omega-6 Fatty Acids and Incident Cardiovascular Disease and Mortality. Circulation. 2019 May 21;139(21):2422–2436. doi: 10.1161/CIRCULATIONAHA.118.038908. PMID: 30971107; PMCID: PMC6582360.
Mititelu, M. et al. (2025). Polyunsaturated Fatty Acids and Human Health: A Key to Modern Nutritional Balance in Association with Polyphenolic Compounds from Food Sources. Foods, 14(1), 46. https://doi.org/10.3390/foods14010046
Mozaffarian D, Micha R, Wallace S. Effects on coronary heart disease of increasing polyunsaturated fat in place of saturated fat: a systematic review and meta-analysis of randomized controlled trials. PLoS Med. 2010 Mar 23;7(3):e1000252. doi: 10.1371/journal.pmed.1000252. PMID: 20351774; PMCID: PMC2843598.
Pachuau, L. et al. (2019). Seed Oils as a Source of Natural Bio-active Compounds. http://dx.doi.org/10.1007/978-981-13-7154-7_8
Petersen, K. S. et al. (2024). Perspective on the health effects of unsaturated fatty acids and commonly consumed plant oils high in unsaturated fat. British Journal of Nutrition, 132(8), 1039–1050. https://doi.org/10.1017/S0007114524002459
Petersen, K. S. et al. (2025). Health implications of linoleic acid and seed oil intake. Nutrition Today. Advance online publication. https://doi.org/10.1097/NT.0000000000000746
Voon, P. T. et al. (2024). Health effects of various edible vegetable oils: An umbrella review. Advances in Nutrition, 15(9), 100276. https://doi.org/10.1016/j.advnut.2024.100276
Hydrogenated Oils – an overview | ScienceDirect Topics. Accessed May 29, 2025. https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/hydrogenated-oils
World Health Organization (WHO). (n.d.). Trans fat. https://www.who.int/news-room/fact-sheets/detail/trans-fat
‘If you’re about to cook with seed oil, stop right now. I’m going to transform how you see your health and your kitchen. Keep watching to find out how.’
Scene: A man in his 30s, clean-cut with a calm intensity, strides down a supermarket aisle in a dark denim jacket and sneakers. He stops in front of the shelves, reaching for a bottle of sunflower oil. He turns to face a camera, brandishing the bottle and issues a dire warning.
‘Seed oils are for greasing engines not cooking.’
If you use social media frequently, this scenario will not be strange to you. Reels, shorts and podcasts abound, each with a single purpose: to convince you to ditch seed oils – immediately.
What They Say
Intellectually, they (seed oils) are bad. Biochemically, they are really, really bad.
—Mary Ruddick.
I strongly believe seed oils are one of the greatest drivers of chronic diseases today.
—Paul Saladino (a self-proclaimed carnivore MD with over 2.5 million followers on Instagram)
Claims that seed oils, derived from rape seed (canola), soybeans, sunflower seeds, etc. can lead to serious medical conditions are all over online health spaces right now. You might have seen wellness influencers like Dr David Jockers and Dave Asprey, using their platforms to denounce these kitchen staples. Self-styled TikTok experts and Instagram fitness gurus are eager to tell their millions of followers that seed oils are ultra-processed agricultural by-products. That there has been an increase in ailments such as inflammation and heart disease and seed oil is to blame.
Are these influencers on the right side of the facts or are they spreading misinformation to their huge audience on behalf of big butter?
What are seed oils?
If we want to make an informed decision about whether to eat seed oils, we have to start with what they are and where they come from and how we get them.
Ancient oils, new advances
Seed oils are edible fats extracted from various plant seeds. Some examples include grapeseed, sunflower, canola, corn and soybean oils.
While some of these oils have traditionally been used in cooking, such as oil collected from crushed sunflower seeds, others, for example canola oil, have only gained gastronomic popularity in the last hundred years. Before the 20th century, canola oil was used to power lamps and for handicrafts because it was difficult to produce. It also smelled like cabbage and tasted pretty bad. Advances in crop development, chemical engineering and food science have helped seed oil makers to find ways to improve the flavour of the oil and to increase yields.
Safe cooking oil supplies are essential for food security. With a global population exceeding eight billion people, producing sufficient plant-based food for everybody just isn’t possible with pre-industrial agricultural techniques. Where once we relied on resource-intensive animal by-products, nuts and fruit oils for our food, now we can also extract useful fats from plant parts that would otherwise be discarded. Today, seed oils in their liquid form are widely used for baking goods, salad dressings, margarine and chips.
How Are Seed Oils Extracted?
Seed oils are extracted through two different methods
- Mechanical Extraction:
This is based on traditional methods of collecting oil from plants, for example olive oil, peanut oil, sunflower oil and linseed oil. People would grind or crush the plant material and then separate the oil from the resulting pulp. These days, seed oils are often extracted using a screw press method, which involves crushing the seeds and slightly heating them to reduce their moisture content.
This technique is widely used for industrial and commercial purposes, but it can only extract 45% oil content from the seeds.
- Solvent Extraction:
Large-scale oil production uses a solvent to extract the oils. Producers wash flaked seeds in a solvent that allows the oils to dissolve and seep out into a vat. This method extracts 100% of the oils, and the end product is of significantly better quality than those generated through mechanical crushing.
After extraction the seed oil will contain impurities and residual solvents. These are removed via a refining process that cleans them up and improves their overall quality. Commonly used solvents include methanol, hexane and heptane. All three of these have a lower boiling temperature than seed oil. Once the extraction phase is finished, the seed oil and solvent mix are heated to boil off the solvent. The workers distill the evaporated solvents from the mixture so that they can reuse these expensive materials. Because the solvents have a low boiling temperature, as long as the oil is uniformly heated to over 70 degrees Celsius for a sufficient time, all the solvent will turn to gas and be drawn off. The European Union has set a maximum residual limit of 1 mg/kg of hexane in our cooking oil. To put that in perspective, that’s a ratio of one part hexane to a million parts oil. The oil is not heated to a high temperature that would change the oil’s properties or make it unsafe to eat. Usually 120 degrees C is the upper limit used for extraction and solvent removal. We use temperatures above this to cook our food.
So should we be worried about the ‘chemicals’ in seed oils? Probably not. Firstly all plant-based foods contain trace contaminants such as heavy metals and microplastics. Plants take up what’s in the soil. If there are metals, pesticides, herbicides or microplastics in the soil, there’s a fair chance they will also be found in any plant growing in it. Even plants with organic certification can absorb whatever is in the soil or water. The seed oil refining system uses materials like water, lye and chelating agents to wash away or trap impurities that occur naturally, through farming methods or during the oil extraction process.
Far from tainting the oils, refining purifies them. The oils are not chemically altered; they are being filtered and cleaned. You could argue that canola oil is less likely to contain contaminants than artisan-made olive oil.
What’s in Seed Oils?
Seed oils are primarily composed of polyunsaturated fatty acids (PUFAs), which are liquid at room temperature and are widely recognized for their benefits to the heart. Some of them include:
- Omega-6 fatty acids, mainly linoleic acid
- Small amounts of omega-3 fatty acids, depending on the source
Other components of seed oils include:
- Vitamin E (tocopherols) in some oils
- Phospholipids
Polyunsaturated Fatty Acids are Essential
Polyunsaturated fatty acids or PUFAs are essential nutrients that our bodies cannot produce on their own; rather we acquire them through everyday foods like sunflower oil, walnuts, flaxseed and fatty fish like salmon or sardines.
A 2025 study highlights some reasons why PUFAs are good for you:
- They build cell membranes, support brain development, keep your skin healthy and even help your body manage inflammation.
- They help protect your heart. When you eat less saturated fat (like butter, red meat, and palm oil) and instead use oils rich in PUFAs, your body manufactures less ‘bad’ LDL cholesterol, which decreases your risk of heart attacks and strokes.
- They help with memory and learning, helping the brain to function well. PUFAs are especially important during pregnancy and early childhood when the brain is developing quickly.
- They can help reduce fat buildup, improve insulin sensitivity and lower certain hormones linked to weight gain and inflammation. Altogether, consuming PUFAs leads to better metabolic health as we age because they manage how our body stores and burns fat.
Guy Johnson, an adjunct professor of food and human nutrition at the University of Illinois Urbana-Champaign and Kevin Fritsche, a professor of animal science and nutrition at the University of Missouri, conducted a systematic review of 15 clinical trials that were carried out between 1993 and 2008 and studied about 500 adults and there was no clear evidence linking the consumption of linoleic acid (the main omega-6 fatty acid in seed oils) to inflammation. Recent research further indicates that polyunsaturated fats, including those found in seed oils, can reduce oxidative stress levels and improve heart health. Evidence also abounds from randomized controlled trials showing that replacing saturated fats with polyunsaturated fats in the diet helps to lower cholesterol levels and reduce the risk of heart disease by as much as 10%.
Are Seed Oils Harmful?
Critics’ Concerns:
So why are people so worked up about seed oils? The anti-seed oil messaging generally falls into two camps:
- Many critics of seed oils raise concerns about the industrial methods deployed to extract them. They point to the use of chemical solvents and high-heat processing, along with the highly refined and ultra-processed nature of these oils, as a potential health risk, especially when consumed on a regular basis. Some studies suggest that these oxidized oils can increase oxidative stress, a process that damages cells and may contribute to cardiovascular disease. On the other hand, if we look at the facts, the chemical solvents are removed and reused by the cooking oil producers, and heat processing doesn’t involve temperatures in excess of those we use every day for frying, baking, roasting, etc. so perhaps these aren’t so concerning after all?
Some of these worries can be traced back to the adverse health effects of partially hydrogenated oils. Once bitten, twice shy, as the adage goes, it’s unsurprising then that people would be wary about industrial influences on food oil. The answer is to get more information.
- Other seed oil detractors are concerned about the innate qualities of the seed oils themselves. These critics believe that certain polyunsaturated fats found in seed oils trigger inflammation.
The abundance of omega-6 fatty acids in seed oils, they say, promotes inflammation, contributing to conditions like heart disease, diabetes and arthritis.
The Truth
So what’s the truth? To find out, we need to ask three key questions:
- Are rates of heart disease going up?
The answer is ‘Yes’. A descriptive epidemiological study comprising data across 204 countries showed that heart disease remains the leading cause of death worldwide, accounting for approximately 20.5 million deaths in 2021, which was nearly a third of all global deaths. The study attributed this steady rise in heart disease to a variety of factors, including high systolic blood pressure, poor diet, diabetes and air pollution. The unequal distribution of resources has led to declines in rates of heart disease in high-income countries, while others face rapid increases.
- Are Seed oils to blame for the increase in heart disease or chronic inflammation?
The answer is ‘No’. Our bodies can’t make omega-3 and omega-6 fatty acids; they are essential nutrients, meaning we can only get them through our diet. We consume more omega-6 than omega-3 and that difference has made some critics speculate that it is unhealthy based on the relative proportions.
Rather than following strict rations, eating a balanced diet helps us to maintain our body system. Our consumption of ultra-processed foods has increased, and with it, obesity rates. These foods contain seed oils, but they also contain large quantities of sugar, salt and refined carbohydrates. Eating foods packed with all of these elements increases our risk of chronic diseases and Metabolic Syndrome.
Seed oils are an easy scapegoat because we can tell ourselves that by switching to ultra-processed foods containing animal fats, we can avoid making less appealing changes to our diet. Seed oils alone are not to blame for any increase in inflammation or heart disease.
- Are people who eat seed oils less healthy than people who eat other kinds of oils?
The answer is No. A review of 38 studies and 811,000 participants found that the consumption of linoleic acid, which is a major component of seed oils, reduced the risk of death from heart disease, type 2 diabetes and even cancer. This provides science-backed evidence that people who consume more seed oils live a healthier life. Another review study published in 2019 also examined 30 unique studies that had 68,000 participants also showed the same reduced risk of heart disease death due to higher levels of linoleic acid.
What Do Official Health Authorities Say?
In addition to the copious scientific evidence showing that seed oils are safe, government health bodies have also reviewed the relative safety of seed oils.
- The World Health Organization reported that over 250, 000 people die annually from consuming trans fat – produced by the partial hydrogenation of liquid oils – and recommended their ban and replacement with polyunsaturated fats like those found in sunflower oil, corn oil and other seed oils.
- The U.S. Food and Drug Administration (FDA) in 2018 concluded that consuming oleic acid (found in sunflower oil, corn oil and others) can reduce the risk of coronary heart disease. Although there is no authorized health claim on seed oils from the FDA, they have issued qualified claims supported by credible scientific evidence highlighting that seed oils are healthy and safe for consumption.
- The American Heart Association (AHA) has consistently encouraged replacing bad fat (trans fat) with good fat (monounsaturated and polyunsaturated) found in seed oils. Some of these oils are name checked – corn oil, soybean oil, sunflower oil – as healthy cooking oil choices that you should consider.
- The European Food Safety Authority (EFSA) has carried out a variety of tests and assessments on different seed oils to confirm if they are harmful or not. The general verdict has been that, under certain conditions, some seed oils (like Allanblackia seed oil) are safe for consumption, while for other seed oils (like rapeseed oil), there is currently no conclusive safety evidence and further studies might be needed.
Learning From History
Seed oils rapidly gained prominence in the food industry in the early 1900s after Procter & Gamble discovered that adding hydrogen atoms to liquid cottonseed oils could raise its melting temperature, solidifying it at room temperature. This property made partially hydrogenated seed oils an ideal replacement for expensive and ‘unhealthy’ saturated fats such as shortening, butter or dripping. Early nutritional research had concluded that saturated fats were ‘bad’, making partially hydrogenated ‘healthy’ oils, AKA trans fats, an attractive alternative. These newly invented oils became the basis of many animal fat substitutes in margarine, baked goods and a variety of crispy snacks.
In the century since hydrogenated oils were introduced, researchers determined that partially hydrogenated oils or trans fats are not safe for us to eat after all, and as a result some countries, including the USA and Canada, have banned their sale for use in food.
Seed oils and partially hydrogenated seed oils are not interchangeable. Adding those hydrogen atoms to seed oil causes a chemical change that alters the way that our body processes them.
Seed Oils in Everyday Cooking
Seed oils can be used for cooking, baking and other culinary activities, but the fatty acids contained in the oils are less stable at high temperatures. This means that they can break down into compounds that may be harmful to our body, especially when they are overheated or reused several times.
So, when you want to cook using seed oils or any oil at all, remember to put it on moderate heat and avoid reusing the oils to prevent harmful chemicals from being released.
Are Seed Oils Safe?
Considering the scientific evidence, seed oils are safe for consumption.
They contain essential PUFAs, such as omega-6, which your body needs. No, they don’t cause inflammation in healthy people ,as shown in a review of 15 controlled trials. What’s more, a meta-analysis of 13 cohort studies demonstrated that you’re not quietly damaging your heart or brain when you cook with seed oils.
Trusted organizations like the American Heart Association and the World Health Organization recommend using seed oils in place of saturated fats like butter or coconut oil.
If, however, most of your seed oil intake comes from deep-fried fast food or heavily processed snacks, the issue isn’t the oil; it’s the overall quality of your diet.
At the end of the day, no single ingredient will make or break your health. What really matters is the big picture: eating whole foods, getting a mix of healthy fats, moving your body and staying curious about what goes on your plate.
References
American Heart Association. (n.d.). Healthy cooking oils.https://www.heart.org/en/healthy-living/healthy-eating/eat-smart/fats/healthy-cooking-oils
Dinicolantonio, James & O’Keefe, James. (2018). Omega-6 vegetable oils as a driver of coronary heart disease: The oxidized linoleic acid hypothesis. Open Heart. 5. e000898. 10.1136/openhrt-2018-000898.
European Food Safety Authority (EFSA). (2018). Scientific opinion on the Tolerable Upper Intake Level for vitamin D. EFSA Journal, 16(7), 5362. https://www.efsa.europa.eu/en/efsajournal/pub/5362
European Food Safety Authority (EFSA). (2023). Safety assessment of the process used to produce recycled PET for food contact materials. EFSA Journal, 21(10), 7706. https://www.efsa.europa.eu/en/efsajournal/pub/7706
Farvid, M. S., & Ding, M., et al. (2014). Dietary linoleic acid and risk of coronary heart disease: A systematic review and meta-analysis of prospective cohort studies. Circulation, 130(18), 1568–1578. https://doi.org/10.1161/CIRCULATIONAHA.114.010236
Hooper, L. et al. (2020). Reduction in saturated fat intake for cardiovascular disease. Cochrane Database of Systematic Reviews, 2020(5), CD011737. https://doi.org/10.1002/14651858.CD011737.pub2
Innes, J. K., & Calder, P. C. (2018). Omega-6 fatty acids and inflammation. Prostaglandins, Leukotrienes and Essential Fatty Acids, 132, 41–48. https://doi.org/10.1016/j.plefa.2018.03.004
Johnson, G. H., & Fritsche, K. (2012). Effect of dietary linoleic acid on markers of inflammation in healthy persons: A systematic review of randomized controlled trials. Journal of the Academy of Nutrition and Dietetics, 112(7), 1029–1041.e15. https://doi.org/10.1016/j.jand.2012.03.029
Li, J., Guasch-Ferré, M., Li, Y., & Hu, F. B. (2020). Dietary intake and biomarkers of linoleic acid and mortality: Systematic review and meta-analysis of prospective cohort studies. The American Journal of Clinical Nutrition, 112(1), 150–167. https://doi.org/10.1093/ajcn/nqz349
Marklund M et al. Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) Fatty Acids and Outcomes Research Consortium (FORCE). Biomarkers of Dietary Omega-6 Fatty Acids and Incident Cardiovascular Disease and Mortality. Circulation. 2019 May 21;139(21):2422–2436. doi: 10.1161/CIRCULATIONAHA.118.038908. PMID: 30971107; PMCID: PMC6582360.
Mititelu, M. et al. (2025). Polyunsaturated Fatty Acids and Human Health: A Key to Modern Nutritional Balance in Association with Polyphenolic Compounds from Food Sources. Foods, 14(1), 46. https://doi.org/10.3390/foods14010046
Mozaffarian D, Micha R, Wallace S. Effects on coronary heart disease of increasing polyunsaturated fat in place of saturated fat: a systematic review and meta-analysis of randomized controlled trials. PLoS Med. 2010 Mar 23;7(3):e1000252. doi: 10.1371/journal.pmed.1000252. PMID: 20351774; PMCID: PMC2843598.
Pachuau, L. et al. (2019). Seed Oils as a Source of Natural Bio-active Compounds. http://dx.doi.org/10.1007/978-981-13-7154-7_8
Petersen, K. S. et al. (2024). Perspective on the health effects of unsaturated fatty acids and commonly consumed plant oils high in unsaturated fat. British Journal of Nutrition, 132(8), 1039–1050. https://doi.org/10.1017/S0007114524002459
Petersen, K. S. et al. (2025). Health implications of linoleic acid and seed oil intake. Nutrition Today. Advance online publication. https://doi.org/10.1097/NT.0000000000000746
Voon, P. T. et al. (2024). Health effects of various edible vegetable oils: An umbrella review. Advances in Nutrition, 15(9), 100276. https://doi.org/10.1016/j.advnut.2024.100276
Hydrogenated Oils – an overview | ScienceDirect Topics. Accessed May 29, 2025. https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/hydrogenated-oils
World Health Organization (WHO). (n.d.). Trans fat. https://www.who.int/news-room/fact-sheets/detail/trans-fat
