Seed oils are having a moment. They’re everywhere these days. You can’t scroll through social media without seeing emotional reels and posts about “the toxic dangers of seed oil.” They have been dramatically labeled as “death in a bottle,” a hidden health hazard that causes inflammation and metabolic dysfunction.

With hot debates raging over whether they are toxic or simply misunderstood, it’s easy to feel confused about their place in a healthy diet. Are seed oils truly your worst enemy, or is the fear overblown?

In this blog, we’ll break down the science behind seed oils, explore their potential risks, and help you make informed choices about whether or not you need to stress about kicking them completely to the curb.

What Are Seed Oils?

So, what exactly is a “seed” oil anyway? Seed oils are simply vegetable oils extracted from the seeds of various plants. They are commonly used in cooking and food manufacturing. Due to their affordability and versatility, seed oils are widely available and often found in processed and packaged foods.

The following is a comprehensive list of seed oils:

• canola oil (rapeseed oil)*
• corn oil*
• cottonseed oil*
• flaxseed oil
• grapeseed oil*
• hempseed oil
• peanut oil
• rice bran oil* (extracted from the outer layer or bran of rice, which is the seed of the rice plant)
• safflower oil*
• sesame oil
• soybean oil*
• sunflower oil*

*These oils are considered “The Hateful Eight”, the most health-sabotaging oils out there, not endorsed by Quentin Tarantino.

Extraction and Processing: Cold-Pressed vs. Refined

How a seed oil is extracted makes a difference. You should know that there are different methods by which oils are extracted, which impact the quality of the oil.

• Cold-Pressed or Expeller-Pressed Oils – Extracted using mechanical pressing without high heat or chemicals, preserving nutrients and antioxidants (e.g., flaxseed or sesame oil).

• Refined Oils – Undergo high-heat processing, chemical solvents (like hexane), and bleaching to increase shelf life and remove impurities, but this process may also strip beneficial compounds and lead to oxidation.

Why Are Seed Oils In Everything?

If you start reading food labels, you’ll notice quickly that seed oils seem to be added to everything: cereal, snack foods, salad dressings, bread, pastries, cookies, margarine, condiments, some plant-based milk (e.g., oat milk, pea milk), the list goes on.

So, why are they so widely used? Mainly because of the reasons listed below.

• Cost-Effective – Cheaper to produce than traditional oils like olive or avocado oil.

• Neutral Flavor – Mild taste makes them versatile for cooking and food production.

• Long Shelf Life – Highly refined versions resist spoilage, making them ideal for processed foods.

• High Smoke Point – Many seed oils can withstand high cooking temperatures, making them popular for frying and baking.

While seed oils are convenient and widely used, their processing methods and high omega-6 content have sparked health concerns, leading to debates about their role in a healthy diet.

The Case Against Seed Oils

There have been many cases made against seed oils. Below are the main highlights.

Metabolic Disrupters

You will often see bar graphs showing the use of seed oils skyrocketing since the 1950s, which is correlated with the significant increase in obesity rates, along with other chronic diseases such as diabetes and heart disease.

High Omega-6 Content & Inflammation

Seed oils are rich in omega-6 fatty acids, which are essential fatty acids, meaning that your body can’t make them, so it is essential that you get them from your diet. The primary omega-6 found in seed oils is linoleic acid, which has been blamed for being pro-inflammatory when consumed in excess.

Many argue that linoleic acid is converted into arachidonic acid in the body, which leads to the formation of other compounds that increase levels of inflammation throughout the body.

Processing & Industrial Refinement

As mentioned, many seed oils undergo high-heat processing and chemical refining, potentially leading to harmful compounds like trans fats and stripping away any beneficial antioxidants.

You will also hear about how seed oils were originally manufactured to be used as an industrial oil to lubricate machinery and were never meant to be used for human consumption.

Oxidation & Free Radicals

The polyunsaturated fats in seed oils are prone to oxidation, which may contribute to cellular damage and aging. This can be especially true when cooked with high heat (deep fryer) and recycled.

The topic of seed oils tends to be very emotionally charged. Many well-known health professionals and influencers have been endorsing the anti-seed oil movement. So, why would you argue? But it’s not so black and white. The human body and nutrition science are more nuanced, so let’s take a closer look.

What Does The Science Say About Seed Oils?

There are two main types of research studies: observational (or epidemiological) studies and interventional or experimental studies (clinical trials).

The majority of evidence from both observational and experimental studies in humans shows either a neutral effect or an actual benefit from using seed oils and not the other way around. Say what?! These studies were not funded by the seed oil industry either.

Before you start throwing bottles of canola oil at me, I am just the messenger, but there is more to the story, so read on. We’re about to get sciency, so don’t fall asleep on me!

Lower Risk Of CVD, Diabetes, And Mortality

When you look at meta-analyses of epidemiological studies, they consistently show that a higher intake of omega-6 polyunsaturated fatty acids (PUFAs), mostly coming from linoleic acid, is associated with a lower risk of cardiovascular disease (CVD) and type 2 diabetes and a lower risk of death.^{1, 2, 3}

This is especially true if you substitute saturated fat (butter, ghee) for seed oils (PUFAs). ^{4, 5, 6, 7} The latest Cochrane review also supported this.⁸ Cochrane reviews are widely considered the gold standard for independent and high-quality evidence.

In 2017, the American Heart Association Presidential Advisory analyzed some of the highest-quality randomized controlled trials on the effects of fats in our diet.

The overall evidence supports the conclusion that replacing saturated fat with polyunsaturated fat from seed oils (mainly linoleic acid) lowers LDL cholesterol and reduces the risk for CVD and death.⁹

Another meta-analysis of 102 controlled-feeding trials showed that replacing saturated fat with seed oils improved fasting blood sugar, insulin resistance, and HgbA1c. ¹⁰

What About Inflammation?

A common opinion you will hear repeatedly is that all vegetable oils, especially seed oils, are inflammatory. Period. All it takes is one convincing TikTok or Instagram reel to have you sold on this belief. But if you dig further, you will find there is very little evidence supporting this.¹¹

Increasing Dietary Linoleic Acid Doesn’t Increase Arachidonic Acid

First off, the hypothesis that increasing linoleic acid in your diet will automatically convert into more arachidonic acid production, causing an inflammatory cascade, is flawed. That’s just not how our bodies respond.

Our bodies have one enzyme that is responsible for this conversion, and it is very picky about when it decides to activate. We have evidence showing that even if you increased your linoleic acid intake by 550%, there is no difference in the tissue levels of arachidonic acid in the body. ¹²

In addition, a recent 2025 systematic review of 11 clinical studies evaluated the impact of seed oils on lipid labs (cholesterol), inflammatory and oxidative markers, and blood sugar control in patients with diabetes and dyslipidemia (unhealthy levels of fats in the blood).

The review determined that seed oils can positively influence lipid/cholesterol levels and blood sugar control while potentially improving oxidative stress and inflammatory markers.¹³

Now that we’ve got the party started, let’s take a look at individual seed oils to see what we find.

Flaxseed, Hempseed, and Sesame Oil

There is less concern over flaxseed, hempseed, and sesame oils sabotaging your health. They are not widely used in processed foods. Both flaxseed and hempseed oil are higher in omega-3 fatty acids, particularly flaxseed oil, which is high in alpha-linolenic acid (ALA). Hempseed oil contains an omega-6 fatty acid called gamma-linolenic acid (GLA). Both are considered to have anti-inflammatory properties. ^{14, 15, 16}

In comparison, sesame oil is higher in omega-6 than omega-3s but contains bioactive compounds that act as antioxidants, potentially reducing inflammation and protecting from oxidation. ^{17, 18, 19}

Canola Oil (Rapeseed Oil)

Canola oil is relatively high in monounsaturated fats (like olive oil). It has a better omega-6 to omega-3 ratio compared to many other seed oils (2:1).

Concerns over canola oil are that it tends to be a highly processed oil coming from genetically modified crops, which usually undergoes high-heat refining and chemical deodorization, potentially leading to oxidation and the formation of unhealthy byproducts.

It would make sense that canola oil would act as a pro-inflammatory. But most research on humans indicates that canola oil has a neutral or slightly positive impact on inflammatory markers. ^{20, 21, 22}

In fact, a systematic review of 42 randomized controlled trials using canola oil found no significant effect on inflammatory markers.²²

Corn, Cottonseed, And Soybean Oil

Corn, cottonseed, and soybean oils are also genetically modified, highly processed oils, containing around 50% linoleic acid. You would think the likelihood of these oils contributing to inflammation would be high.

Let’s start with soybean oil. One study measured inflammatory markers in 98 adults with metabolic syndrome and compared soybean oil to flaxseed and fish oil over two months. There were no significant changes to inflammatory markers with any of the oils.²³

Another double-blind randomized controlled trial compared soybean oil to olive oil in 210 patients. Improvement in inflammatory markers was no different in either group.²⁴ A review, summarizing the effects of soybean oil, stated that “clinical evidence indicates that soybean oil does not affect inflammatory biomarkers, nor does it increase oxidative stress.” ²⁵

Corn and cottonseed oils basically show the same. Consuming 4 Tbsp a day of corn oil for four weeks showed no significant impact on inflammatory markers.²⁶ Cottonseed oil was actually shown to protect against intestinal inflammation.²⁷

Sunflower Seed, Safflower, And Grape Seed Oil

Both sunflower seed oil and safflower oil are commonly found in many processed foods. Sunflower seed oil is about 20% linoleic acid, and safflower oil contains a whopping ~75% linoleic acid. These oils are known for their high smoke point and can be used in high-heat cooking.

A randomized controlled trial compared the effects of sunflower oil to extra virgin olive oil on markers of inflammation and oxidative stress. There was no significant change in either group. ²⁸ Another study gave 79 obese or overweight elderly patients 30 ml of either flaxseed, olive, or sunflower oil for 90 days. All three groups reduced pro-inflammatory properties. ²⁹

Safflower oil, despite containing one of the highest amounts of linoleic acid, appears to have the same impact. One randomized controlled trial looked at 55 post-menopausal, obese women with type 2 diabetes and gave them 8g of safflower oil for 8 weeks. They showed improved blood sugar, inflammation, and blood lipids. ³⁰

Another double-blind, placebo-controlled randomized study compared safflower oil to flaxseed oil (2 Tbsp/day) over 3 months and found no significant changes to inflammatory markers for both groups.³¹

Grape seed oil is not as commonly used, so fewer studies are looking at it. It contains ~70% linoleic acid. One study showed that consumption of grape seed oil seems to improve inflammatory markers and insulin resistance in overweight/obese women, but this is just one study. ³²

Rice Bran And Peanut Oil

Both rice bran and peanut oil are similar as they contain around 35% linoleic acid and have a high smoke point, making them suitable for high-temperature cooking. They also have a relatively mild flavor.

A randomized controlled trial looking at 40 men with coronary artery disease found that 30 grams per day of rice bran oil within a standard diet could be considered an effective approach in improving cardiometabolic risk factors and inflammation. ³³

Consuming a blend of 20% cold-pressed unrefined sesame oil and 80% refined rice bran oil as cooking oil for 8 weeks lowered blood sugars and improved the lipid profile in type 2 diabetes patients. ³⁴

Another randomized, double-blind study followed 251 people for a year who either consumed peanut oil, corn oil, or an oil blend in cooking. There were no significant changes to high-sensitivity C-reactive protein (a measure of inflammation), lipids, blood sugar, or insulin in all three groups. ³⁵

What About Heated Seed Oils?

The main concern over heated seed oils is that their high omega-6 content makes them more prone to oxidation when exposed to very high cooking temperatures. This oxidation can produce harmful compounds, including trans fats, free radicals, and aldehydes, which can damage cells and contribute to inflammation and oxidative stress.

The risk is potentially greater with highly refined oils and repeated heating (like deep frying), which further degrades the oil’s stability and nutritional quality. This is a valid concern. So, do we have evidence that this is actually occurring?

A systematic review looked at 33 trials and found that when seed oils were heated to around 200 degrees Celsius (392 degrees Fahrenheit), and you heated that oil for 15-45 minutes, there was no significant increase in trans fats. This is equivalent to cooking with medium heat on your stove. ³⁶

When the temperature goes above 200 degrees Celsius, however, that’s when you start seeing the formation of trans fats, especially when heated for longer periods and recycling the oil over and over again, like the deep fryers in restaurants and McDonald’s.

So, overall, from the studies we have looked at, cooking with seed oils doesn’t seem to be an issue unless used in high-heat cooking.

What About Beef Tallow?

You’ve probably been hearing a lot about beef tallow lately, so just in case you don’t know, we will break down what it is first.

Beef tallow is a rendered fat, created by melting down the fat from a cow to separate it from other tissues and “impurities” (meat scraps, gelatin, bacteria). It’s then cooled and becomes solidified at room temperature. It’s used in cooking, baking, and now people are lathering it all over their skin.

Funny enough, beef tallow is also used as a machinery lubricant, and is used to make motor oil and other “industrial” purposes. So, I guess it shares something in common with seed oils.

Is Beef Tallow And Butter A Better Option?

Some people are advocating that, instead of seed oils, we should go back to using beef tallow to fry our French fries and use butter for cooking. The thought is that they are healthier options since they are more “natural.” But, there are a lot of natural things that aren’t that great for us. Mercury is natural. That doesn’t mean it’s healthy.

I think we have already established that butter is not the best option. People will still disagree, but there is strong and consistent evidence showing that when we replace saturated fats like butter with unsaturated fats from seed oils, there are better health outcomes. That’s what really matters.

Beef tallow contains close to 50% saturated fat (along with monounsaturated fat and a small amount of PUFA) compared to butter, which contains around 63%. Beef tallow raises LDL cholesterol levels and triglycerides similar to butter, but not as much.⁴

I want to clarify that there is nothing wrong with saturated fat. Most healthy fats contain a little saturated fat along with unsaturated fat. Saturated fat in the right amount can be part of a healthy diet. When saturated fat becomes a problem is when we consume it in excess.

All fats oxidize and break down with prolonged cooking using very high heat, but it’s true that saturated fats are more stable for longer periods in comparison to seed oils.

Maybe that means something to you if you consume a lot of fast food or deep-fried foods, but does eating a lot of food fried in saturated fat lead to better health outcomes? Common sense would say no.

What About Your Omega-6 To Omega-3 Ratio?

There used to be the opinion that the real issue was eating a high proportion of omega-6 fats (linoleic acid) in comparison to omega-3 fats (ALA: alpha-linolenic acid). I actually mentioned this in the blog Anti-inflammatory Diet For Menopause.

Your body has enzymes that break ALA into eicosapentaenoic acid (EPA) and a small amount into docosahexaenoic acid (DHA).  EPA and DHA are long-chain fatty acids that are essential for your health. Turns out that linoleic acid (omega-6) requires the same enzyme to turn into arachidonic acid, a long-chain fatty acid.

The thought was that since they compete for the same enzyme, eating less omega-3s than omega-6s would create more inflammation in the body. But remember, this enzyme is finicky. Your body isn’t stupid.

Some studies have tested this theory, and it doesn’t seem to be much of a concern. ^{37, 38, 39} It is still important to ensure you are getting in enough omega-3s. For this reason, I probably won’t update previous blog posts where I have mentioned the omega-6 to omega-3 ratio. For more on good sources of plant-based omega-3s, you can check out the blog: Top 5 Vegan Omega-3 Sources.

What’s The Real Issue?

So, why are obesity rates, the incidence of cancer, and chronic diseases appear to be significantly increasing over the past few decades? It all points to seed oils, right? If only things were so simple, to blame everything on one ingredient in our food. The real truth is that there are multiple reasons.

For one thing, the human population has dramatically increased. According to Our World In Data, a little over a century ago, our population was 2 billion people. In 2025, that number has grown to approximately 8.2 billion.

On top of that, we are living longer. In 1950, the average life expectancy was only 45.51 years. In 2025, that has increased to 73.49 globally and 79.4 years in the United States. ⁴⁰

How we grow our food, what and how we eat, have dramatically changed over the years. We started genetically modifying foods in the 1990s, along with using Roundup on our crops. Fast food and convenience foods are available on every street corner. Approximately 60% of the American diet comes from processed foods.

These highly processed foods contain multiple additives, artificial sweeteners, dyes, and emulsifiers on top of oils, sugar, and salt. They are often engineered to delay or reduce the feeling of fullness (satiety), causing us to overeat and gain weight.

Perspective

Putting all the blame on seed oils is not looking at the big picture. The context of your overall diet matters. If you feel better eliminating seed oils from your diet, it’s not surprising. If you reduce your intake of prepackaged and processed foods, which often contain seed oils, and include more whole foods in your diet, you are going to feel better.

I’m all about questioning authority and well-known institutions on guidelines and recommendations that don’t make sense or have limited, poor-quality studies to back them. I disagree with the American Heart Association’s take on coconut oil (specifically, virgin unrefined coconut oil). But that’s another blog post!

Personally, I don’t use a lot of added seed oils in my diet, rarely eat fried food, and try to keep processed foods to a minimum. So, I don’t freak out if an item contains canola or safflower oil. It doesn’t matter because my overall diet is pretty darn healthy.

I highly recommend watching this video by Dr. Gil Carvalho, Nutrition Made Simple on Seed Oils, if you want an educated, unbiased take on the topic. He makes some really good points.

My Recommendations

The healthiest sources of fat, honestly, come from whole foods like nuts, seeds, olives, and avocado. I talk a lot about these in the blog: The Best Vegan Healthy Fats. Minimizing your intake of packaged, processed foods will automatically help keep your fat intake coming from oils in a healthier range.

So, what oil is the healthiest? The following are my top 3 recommendations:

• Extra Virgin Olive Oil: This should be your staple oil. Numerous studies support the health benefits of olive oil.
• Avocado Oil: Use with higher heat cooking (air frying, frying, roasting). It’s rich in monounsaturated fats, vitamin E, and other beneficial compounds like lutein (a beneficial carotenoid antioxidant ).
• Toasted Sesame Oil: This is a good finishing oil that adds a nutty flavor to stir-fries and Asian dishes. You want to add it towards the end of your cooking, as it has a low smoke point.

I also use a limited amount of virgin unrefined coconut oil as a swap for butter for certain things like baking, pancakes, etc.

If you do use other seed oils or find them in prepackaged foods, look for organic, expeller-pressed, cold-pressed, or high oleic (more monounsaturated fat). Some people don’t care about GMOs, so organic is optional; it’s just my personal preference.

Bottomline: Are Seed Oils Your Worst Enemy?

So far, the majority of evidence from both observational and experimental studies in humans shows either a neutral effect or an actual benefit from using seed oils.

There is strong evidence that supports consuming unsaturated fats, particularly PUFA from seed oils, instead of saturated fats, reduces the risk of cardiovascular disease and type 2 diabetes and leads to better health outcomes.

Seed oils are not inherently harmful when consumed in moderation and as part of a balanced, whole-food diet. The type of seed oil (cold-pressed vs. refined), the quantity, and the overall dietary context matter more than simply labeling them good or bad.

When it comes to health, or anything for that matter, it’s always better to make an informed choice that aligns with your values instead of forming a judgment based on fear or popular opinion. At the end of the day, you get to choose.