Have you heard of the hateful eight? No, not the Tarantino movie, the 8 most common seed oils that are present in the American diet. These include: canola oil (aka rapeseed oil), corn oil, grape-seed oil, soybean oil, sunflower oil, safflower oil, rice bran oil and peanut oil. Lately, many social media health gurus have been calling them out for their negative effects on our health.
So are these completely trustworthy professionals onto something? Should seed oils be put on the chopping block? Let’s get into it!
What Are Seed Oils?
Seed oils are exactly what they sound like, oil that is derived from seeds. The thing about seed oil is it’s a heck of a lot harder to extract than, say, olive oil. Logically we’ve turned to more aggressive tactics in order to extrude the oil. Here are the most widespread ones in order:
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Full Pressing: Most of the time using a screw like presser that crushes the seeds and expels most of the oil.
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Solvent Extraction: Like most food related things, people decided to add chemicals into the mix. A compound called hexane is used to chemically remove most of the remaining oil. The hexane that is left in the oil is (almost) completely removed hereafter. More on this toxic chemical in a bit.
-
Hydraulic Press: Here the seed, now mangled, is heated and crushed to kingdom come with the biggest weight the manufacturer could get their hands on, relieving the seed of its last oil remains.
The result of this process is a cheap and versatile ingredient, generally polyunsaturated and rich in Omega 6 fatty acids. Because of the low price tag, we’ve gotten to see these oils on most ultra processed foods that are sold around the country.
Seed Oil Health Concerns
All over the internet you can find way too many health gurus and others alike claiming the toxic nature of seed oils. Are they right? Let's get right into what the dark side of seed oils are!
ProInflammatory Effect of Omega 6: Most seed oils are pretty high in this essential fatty acid. Online forums will tell you it’s actually bad for you, but real science will tell you that you need Omega 6, hence why it is essential. The inflammatory effect is actually a result of an imbalance of Omega 3 and 6. The ideal ratio is 1:1, and less than 100 years ago people's diets had a ratio of 1:4. Fast-forward to today and, you can say we got carried away with the Omega 3, given our current 20:1 ratio. So let's not blame Omega 6 for the inflammation.
Chemicals: Remember hexane from before? This compound is a well documented nerve toxin, and repeated high exposure can result in peripheral neuropathy. Harvard Health found there is roughly 0.8 parts per million (ppm) of this stuff in vegetable oils. It’s not nothing, but it is certainly a far cry from the 500ppm at which the first neurological effects are found. The good news is that hexane and all of its breakdown products are all excreted within 1-2 days.
Polycyclic Aromatic Hydrocarbons (PAHs): With a name like that it can’t be good. Ever leave the oil heating up and come back to it smoking? Careful! You might start a fire, and get some of these PAHs in your food. These are carcinogenic chemical compounds that form when we overheat oils and can damage the liver and kidneys. Just keep an eye on the stove and you’ll be fine.
Ultra Processed Food (UPF): Due to the much cheaper production costs, seed oils have found a large demand in the unhealthy food sector. Things like industrial baked goods, frozen foods and snacks are all riddled with seed oils. This (obviously) means that people who have a high UPF diet, will be: more unhealthy, have more inflammation and undoubtedly consume more seed oils. UPFs are unhealthy as is, but do seed oils add to this, or is it simply due to the grotesque amounts consumed? Probably the latter, and this highlights the importance of looking at the big picture. Correlation is not causation.
Benefits of Seed Oils
Now on the lighter side of things, what are the goodies these oils provide?
Improves Lipid Profile: Simply put, the lipid profile doesn't just measure the amount of lipids in your blood. Arguably the most relevant parameters tested are the concentrations of lipid transporter proteins (lipoproteins). There are 3 main groups: high density lipoprotein (HDL), low density lipoprotein (LDL) and very low density lipoprotein (VLDL). HDL is responsible for eliminating excess cholesterol. The other two are responsible for carrying the cholesterol to our body’s cells or liver for long-term storage. Since most of us have an excess of these nutrients in our diets, storing them has a whole slew of negative side effects. So consuming seed oils will reduce harmful LDL and increase beneficial HDL. This contributes to the lowering of the risk of developing cardiovascular disease due to atherosclerosis.
Heart Healthy / Reduce Cardiovascular Disease: Improving the blood lipid profile is definitely one of the contributing factors to seed oils being heart healthy. But there is another great benefit that cannot be seen by observing seed oils alone. We need to compare them to saturated fats like coconut oil, palm oil, butters and many more. The reason being is their shape. Saturated fats are completely straight. This means that unlike its twisty counterparts, saturated fats stack much easier, forming plaque that can cause many heart diseases like high blood pressure, stroke and heart attacks. Imagine the ease of stacking paper versus the frustration of trying to stack twigs, that’s really what’s going on here.
What Are Seed Oils?
Seed oils are exactly what they sound like, oil that is derived from seeds. The thing about seed oil is it’s a heck of a lot harder to extract than, say, olive oil. Logically we’ve turned to more aggressive tactics in order to extrude the oil. Here are the most widespread ones in order:
-
Full Pressing: Most of the time using a screw like presser that crushes the seeds and expels most of the oil.
-
Solvent Extraction: Like most food related things, people decided to add chemicals into the mix. A compound called hexane is used to chemically remove most of the remaining oil. The hexane that is left in the oil is (almost) completely removed hereafter. More on this toxic chemical in a bit.
-
Hydraulic Press: Here the seed, now mangled, is heated and crushed to kingdom come with the biggest weight the manufacturer could get their hands on, relieving the seed of its last oil remains.
The result of this process is a cheap and versatile ingredient, generally polyunsaturated and rich in Omega 6 fatty acids. Because of the low price tag, we’ve gotten to see these oils on most ultra processed foods that are sold around the country.
Seed Oil Health Concerns
All over the internet you can find way too many health gurus and others alike claiming the toxic nature of seed oils. Are they right? Let's get right into what the dark side of seed oils are!
ProInflammatory Effect of Omega 6: Most seed oils are pretty high in this essential fatty acid. Online forums will tell you it’s actually bad for you, but real science will tell you that you need Omega 6, hence why it is essential. The inflammatory effect is actually a result of an imbalance of Omega 3 and 6. The ideal ratio is 1:1, and less than 100 years ago people's diets had a ratio of 1:4. Fast-forward to today and, you can say we got carried away with the Omega 3, given our current 20:1 ratio. So let's not blame Omega 6 for the inflammation.
Chemicals: Remember hexane from before? This compound is a well documented nerve toxin, and repeated high exposure can result in peripheral neuropathy. Harvard Health found there is roughly 0.8 parts per million (ppm) of this stuff in vegetable oils. It’s not nothing, but it is certainly a far cry from the 500ppm at which the first neurological effects are found. The good news is that hexane and all of its breakdown products are all excreted within 1-2 days.
Polycyclic Aromatic Hydrocarbons (PAHs): With a name like that it can’t be good. Ever leave the oil heating up and come back to it smoking? Careful! You might start a fire, and get some of these PAHs in your food. These are carcinogenic chemical compounds that form when we overheat oils and can damage the liver and kidneys. Just keep an eye on the stove and you’ll be fine.
Ultra Processed Food (UPF): Due to the much cheaper production costs, seed oils have found a large demand in the unhealthy food sector. Things like industrial baked goods, frozen foods and snacks are all riddled with seed oils. This (obviously) means that people who have a high UPF diet, will be: more unhealthy, have more inflammation and undoubtedly consume more seed oils. UPFs are unhealthy as is, but do seed oils add to this, or is it simply due to the grotesque amounts consumed? Probably the latter, and this highlights the importance of looking at the big picture. Correlation is not causation.
Benefits of Seed Oils
Now on the lighter side of things, what are the goodies these oils provide?
Improves Lipid Profile: Simply put, the lipid profile doesn't just measure the amount of lipids in your blood. Arguably the most relevant parameters tested are the concentrations of lipid transporter proteins (lipoproteins). There are 3 main groups: high density lipoprotein (HDL), low density lipoprotein (LDL) and very low density lipoprotein (VLDL). HDL is responsible for eliminating excess cholesterol. The other two are responsible for carrying the cholesterol to our body’s cells or liver for long-term storage. Since most of us have an excess of these nutrients in our diets, storing them has a whole slew of negative side effects. So consuming seed oils will reduce harmful LDL and increase beneficial HDL. This contributes to the lowering of the risk of developing cardiovascular disease due to atherosclerosis.
Heart Healthy / Reduce Cardiovascular Disease: Improving the blood lipid profile is definitely one of the contributing factors to seed oils being heart healthy. But there is another great benefit that cannot be seen by observing seed oils alone. We need to compare them to saturated fats like coconut oil, palm oil, butters and many more. The reason being is their shape. Saturated fats are completely straight. This means that unlike its twisty counterparts, saturated fats stack much easier, forming plaque that can cause many heart diseases like high blood pressure, stroke and heart attacks. Imagine the ease of stacking paper versus the frustration of trying to stack twigs, that’s really what’s going on here.
Safer Cooking With Seed Oils: A Few Tips
Before we go, we want to make some important points for your at-home cooking experiences.
Yes, we already said it, but in case you missed its importance, heating oil past its smoke point is very bad. A super easy way to make sure that your oils or fats are not breaking down and forming harmful compounds like PAHs is to make sure that your oil is never smoking. If it does, it would be best to rid yourself of that oil. Every oil has a different smoke point temperature, saturated fats like butter or beef tallow are much more stable which means that it will take more temperature to start forming damaging compounds. But, that doesn't mean that they don't form.
Seed oils also get a bad reputation because they oxidize very fast. This causes the oil to break down and possibly form harmful compounds. Two ways to prevent this is is to:
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Screw the cap on tightly! Oxygen can’t get in if you seal it properly. Well 0.000007 ounces to 0.00002 ounces of oxygen slipped through the cap every day but who’s counting. This means that it would take 273 years for just 2 oz to get in and the news is, unless you are planning to have the canola oil in your pantry be a family heirloom you probably finished it off in less than a month.
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Seeds oils are vampires! Keep them away from light, because light acts as a catalyst for oxidation. Store them preferably in a dark place like a cupboard. Your oil will last a whole lot longer.
Final Thoughts
Seed oils may not be perfect, but they’re not dietary villains either. Instead of an all-or-nothing approach, it’s more about balance: keeping omega-6 in check, avoiding overheating, and keeping an eye on processed food intake. In short, there’s no need for panic. Just a little mindfulness goes a long way toward making better choices in the kitchen.
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