Are Seed Oils Bad for You?

10 November 2025

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If you’ve scrolled through your favorite social media app lately, chances are you’ve stumbled upon fiery debates about seed oils. One post might claim their high omega-6 content makes them “toxic,” fueling everything from inflammation to chronic disease, while the next video from a medical provider praises their role in promoting heart health.

These conflicting messages leave many Americans scratching their heads, wondering if seed oils are a friend or foe to health. The truth isn’t as clear-cut as either side might suggest, but in this blog, we’ll explore what’s factual, what’s exaggerated and how you can make informed decisions about incorporating healthier oils into your diet.

In this blog, we speak to Jonathan Miller, M.D., a board-certified family medicine physician with INTEGRIS Health Medical Group North MacArthur, to learn more.

“Seed oils are not inherently harmful and can be part of a healthy diet when used in moderation and in minimally processed forms,” Miller says. “By focusing on whole foods, reducing reliance on overly processed options and selecting minimally refined oils, you can make informed choices that work for your health and lifestyle.”

What are seed oils?

Catch up quick: Seed oils are extracted from the seeds of plants such as sunflower, safflower, soybean and corn. They are commonly used in processed foods and fast food due to their low cost, mild flavor and versatility.

Seed oils are derived from seeds through chemical or mechanical processes.

Common examples include canola, corn, cottonseed, grapeseed, soy, rice bran, sunflower and safflower oils.
Seed oils are stable at high temperatures, making them suitable for frying and baking.
They contain unsaturated fats, particularly omega-6 fatty acids, which are essential for the body but must be balanced with omega-3s for optimal health.

Chemical extraction is the most common and cost-effective method used for large-scale production.

The seeds are cleaned, ground into fine particles and mixed with a chemical solvent, usually hexane, to dissolve the oil.
The solvent-oil mix is then heated, causing the hexane to evaporate and leaving only crude seed oil behind.
Crude oil is treated with water or acid to remove impurities like phospholipids and other water-soluble compounds.
The crude oil undergoes a series of refining steps, including neutralization (removal of free fatty acids), bleaching (to eliminate pigmentation) and deodorization (to remove unpleasant odors).
As a result of processing, chemically extracted oils have a higher smoke point and longer shelf life.

Mechanical extraction relies on physical force to extract oil without the use of solvents or chemicals – at the store, these oils are marketed as "cold-pressed" or "expeller-pressed."

Cold pressing is performed at temperatures below 120 F to minimize heat exposure, preserving nutrients, flavor and aroma.
Expeller pressing involves crushing and pressing using a mechanical screw expeller, a process that elevates temperatures due to friction and can therefore reduce nutrient levels compared to cold pressing.
Mechanically extracted oils have a lower smoke point and a shorter shelf life because they’re at a higher risk of oxidation.

The health impact of seed oils

At a glance: Seed oils are a dietary mainstay in American cooking. However, they’ve also sparked heated debates about their effects on health. While some praise these oils for their affordability, availability and potential heart health benefits, others question their high omega-6 content, processing methods and potential links to chronic inflammation.

The case against seed oils

Critics of seed oils highlight potential health risks and question their role in modern diets.

Omega-6 fatty acids are a type of polyunsaturated fat found in many seed oils.
While omega-6 fats are essential to the body, consuming them in excessive quantities, particularly without a balance of omega-3s, can potentially promote inflammation.
Yes, inflammation is a natural response that helps your body heal, but chronic or unregulated inflammation can become harmful.
Prolonged inflammatory states may contribute to higher risks of diseases such as cardiovascular issues, autoimmune disorders and metabolic syndrome.

The typical western diet is skewed, with omega-6 to omega-3 ratios reaching 10:1 or higher, far above the ideal ratio of 2:1 or 3:1.

The only seed oil that comes close to that ratio is canola oil at 2:1.
Conversely, grapeseed, safflower, sunflower, cottonseed and corn oils have trace amounts of omega-3s, making for a less-than-desirable ratio.

The processing methods have also raised concerns.

Most seed oils undergo extensive refining, which removes nutrients and introduces additives.
Seed oils are sensitive to heat, light air and can oxidize, which can create harmful compounds like free radicals.

A battle between marketing and science has further divided the discussion.

Critics suggest seed oils gained popularity partly due to aggressive marketing campaigns in the mid-20th century that portrayed them as healthier than animal fats like butter or lard.
Some argue this narrative overlooked the long-term effects of processed oils to market them as modern and convenient.

The case supporting seed oils

Proponents of seed oils argue that seed oils, when used appropriately, can provide a good source of unsaturated fats as part of a balanced diet.

Seed oils contain both monounsaturated and polyunsaturated fats.
Monounsaturated fats support heart health by reducing LDL cholesterol.
Polyunsaturated fats, particularly omega-6 fats, play a key role in brain function, skin health and reducing cholesterol levels.

Omega-6 fatty acids, particularly linoleic acid, frequently come under scrutiny in discussions about inflammation.

When you consume foods high in omega-6 fats, linoleic acid is metabolized in your body.
A small portion of this linoleic acid is converted into arachidonic acid, a fatty acid involved in a range of biological processes.
Arachidonic acid is often labeled as inflammatory because it produces molecules like prostaglandins and leukotrienes that can trigger the inflammatory response.
However, the body regulates how much linoleic acid it converts into arachidonic acid, and the amount is actually small.
Plus, arachidonic acid is also essential for creating molecules known as lipoxins and resolvins, which resolve inflammation and promote tissue healing.

Health organizations have endorsed consuming seed oils.

They believe health risks of seed oils are often overstated, and their benefits, particularly when replacing saturated fats, are well-supported by decades of research.
For example, the American Heart Association in 2024 fought back against the negative press against seed oils and went as far to say “there’s no reason to avoid seed oils.”
A recent study published in JAMA Internal Medicine shows that replacing saturated fats like butter with plant-based oils (safflower, soybean, corn, canola and olive oil) resulted in a 16 percent reduction in mortality.

The amount and context matters when consuming seed oils.

Eating omega-3-rich foods such as fish, flaxseeds or walnuts can help offset concerns about omega-6 dominance.
Critics note that issues attributed to seed oils often stem from overuse or reliance on processed food, rather than the oils themselves.
The truth is omega-3s are more anti-inflammatory, but that doesn’t mean omega-6s are pro-inflammatory – it’s just not as beneficial.

The health impact of seed oils being highly processed or containing trace amounts of solvents like hexane is unclear.

That said, you can still choose expeller- or cold-pressed seed oils to retain more antioxidants, vitamins and essential fats.
Examples include expeller-pressed peanut oil, expeller-pressed sesame oil or cold-pressed flaxseed oil.

Where the confusion stems from

Consider this: The debate about seed oils is fueled by a mix of scientific complexity, subjective interpretations and misinformation.

Research on seed oils and their health effects often appears contradictory.

Some studies emphasize benefits like lower cholesterol, while others focus on potential risks, such as promoting inflammation.
These mixed conclusions leave consumers uncertain.

Not all seed oils are the same.

Minimally refined oils preserve more nutrients, while heavily refined or hydrogenated oils may pose greater risks.
The distinction is not always clear to consumers, adding to the confusion.

The backlash against seed oils coincides with the rise of "natural" and "whole food" movements.

These trends often favor minimally processed oils such as extra virgin olive oil, coconut oil and grass-fed butter.
This shift has led to polarizing narratives about seed oils.

Social media and online forums often amplify extreme views, framing seed oils as either "superfoods" or "toxic."

This dichotomy oversimplifies their nuanced role in nutrition and makes it harder for consumers to discern facts from fear mongering.

Best oil to cook with

Key points: Which oils should you cook with? In an ideal world, cold-pressed olive oil for cold dishes and avocado oil for sautéing or frying can provide more health benefits. However, the reality is not everyone can afford these higher-priced oils. If you have to choose a seed oil, canola oil has the best omega-6 to omega-3 ratio.

Extra virgin olive oil is high in monounsaturated fats, particularly oleic acid, which supports heart health by improving cholesterol levels and reducing inflammation.

Cold-pressed olive oil also contains antioxidants such as vitamin E and polyphenols, which help combat oxidative stress.
The smoke point of 375 F makes it only suitable for low to medium-heat cooking such as sautéing, roasting vegetables or in sauces and salad dressings.

Avocado oil is also high in heart-healthy monounsaturated fats.

It’s also a good source of vitamin E and lutein, an antioxidant that supports eye health.
A high smoke point between 480 and 520 F makes it a popular option for high-heat cooking.
Thanks to a mild taste profile, it also works well in dressings or baking.

The bottom line about seed oils

Final takeaways: Seed oils are neither inherently good nor inherently bad. Their health effects depend on the type of oil, how it’s used and its place in the larger context of a balanced diet.

For cooking, oils like canola and soybean, which contain both omega-6s and omega-3s, are excellent choices.

Instead of focusing on oil choices, focus on reducing intake of ultra processed foods and eat more fruits and vegetables.

Any type of diet high in fat, regardless of whether the fat is good or bad for you, can lead to weight gain and other health complications.
For example, eating a bag of chips fried in avocado oil compared to soybean oil is less about the oil used and more about how much sodium and preservatives are used.