Are Seed Oils Ultra-Processed? What the Research Actually Says

Quick Answer: Most seed oils sold in grocery stores are ultra-processed. Refined canola, soybean, sunflower, safflower, and corn oils are produced through hexane solvent extraction, bleaching, and high-temperature deodorization, putting them in NOVA Group 4. Cold-pressed or expeller-pressed versions skip the solvents and sit in NOVA Group 2.

The seed oil conversation has gotten loud lately. On podcasts, in restaurant menus advertising "no seed oils," in nutrition threads that go nowhere fast. Most of that noise skips a simple, answerable question: are these oils actually ultra-processed by the definition food researchers use?

The answer depends on one thing: how the oil was made.

What counts as a seed oil?

A seed oil is any oil pressed or extracted from the seed of a plant. That covers canola (rapeseed), soybean, sunflower, safflower, corn, cottonseed, and grapeseed. Flaxseed and sesame oil fit here too.

A common point of confusion: olive oil is not a seed oil. It is pressed from the fruit of the olive, not the seed. Avocado oil (pressed from fruit flesh) and coconut oil (pressed from coconut meat) are also fruit-derived, not seed-derived. These oils come up constantly in seed oil comparisons, but they belong in a different category from the start.

The processing question begins after harvest. Seeds are small and oil-dense, which makes them harder to press efficiently than fruit. That practical reality is what drives the industrial extraction methods that define the NOVA status of most commercial seed oils.

Are seed oils considered ultra-processed under NOVA?

Most commercial seed oils are NOVA Group 4. Here is why.

The NOVA classification system was developed by researchers at the University of São Paulo to categorize foods by the nature and extent of industrial processing, not by nutrient content. Under NOVA, a food reaches Group 4 when its production involves industrial processes or ingredients not used in home cooking. source: Monteiro CA et al., Public Health Nutrition, 2018, doi:10.1017/S1368980017001379

Refined canola, soybean, sunflower, safflower, and corn oil all qualify as NOVA Group 4 because their refining process uses hexane (a petroleum-derived solvent), chemical bleaching agents, and high-temperature deodorization. You cannot replicate that process in a kitchen. The resulting product is highly consistent, shelf-stable, and largely flavorless, which is exactly what the food industry needs, but it is produced through an industrial method with no domestic equivalent.

Cold-pressed and expeller-pressed seed oils are different. Mechanical pressing extracts oil through physical pressure alone, without solvents. That process is closer to NOVA Group 2 (processed culinary ingredient), alongside butter, lard, and unrefined coconut oil. source: Monteiro CA et al., Public Health Nutrition, 2018

The practical read: if the label says "refined" or just lists the oil without specifying extraction method, assume hexane. If it says "cold-pressed" or "expeller-pressed," you are likely looking at NOVA Group 2.

For a full breakdown of the classification logic, see ultra-processed foods explained.

How are seed oils actually refined?

The refining process for most commercial seed oils runs through five stages. Understanding those stages is why researchers put the output in NOVA Group 4.

Solvent extraction. Seeds are ground, heated, and bathed in hexane to pull out the oil. Hexane is a hydrocarbon derived from petroleum refining. It dissolves fats efficiently, which is why the industry uses it at scale. Residual hexane is evaporated from the crude oil after extraction. The FDA limits hexane residues in finished edible oils to 25 ppm, though typical finished-product levels are lower than that limit. source: FDA 21 CFR 173.270

Degumming. Crude oil contains phospholipids that cause cloudiness and reduce shelf life. A warm water or acid wash removes them.

Bleaching. The oil is treated with activated bleaching clay to remove pigments, residual soaps, and trace metals. The output is pale and nearly colorless.

Deodorization. This is the step that receives the most regulatory scrutiny. The oil is steam-treated under high heat (200-270°C) to strip out volatile flavor and odor compounds. At those temperatures, glycidyl esters and 3-monochloropropane-1,2-diol (3-MCPD) fatty acid esters can form as process contaminants. EFSA reviewed these compounds and raised concern specifically about glycidyl esters, which are metabolized to glycidol, a compound EFSA considers genotoxic. EFSA established tolerable intake values and called for reformulation of deodorization conditions to reduce formation. source: EFSA CONTAM Panel, EFSA Journal, 2016, doi:10.2903/j.efsa.2016.4426

Winterization. Some oils are chilled to remove waxes so the oil stays clear at refrigerator temperatures.

None of these steps happen at home. The output is safe to consume within regulatory limits, but the production method is what classifies it as ultra-processed.

Are seed oils bad for you? What the research shows about omega-6 and inflammation

This is the part of the seed oil conversation that generates the most heat and the most confusion.

Commercial seed oils are high in omega-6 polyunsaturated fatty acids (PUFAs), mainly linoleic acid. The mechanistic argument against them: linoleic acid is a precursor to arachidonic acid, which feeds into inflammatory eicosanoid signaling pathways. The concern is plausible at the molecular level. Western diets have shifted substantially toward higher omega-6:omega-3 ratios over the past century, and that shift has been associated with inflammatory disease patterns. source: Simopoulos AP, Biomedicine and Pharmacotherapy, 2002, doi:10.1016/S0753-3322(02)00253-6

But mechanisms are not outcomes. The human trial evidence is more complicated than the influencer takes suggest.

The American Heart Association's 2017 Presidential Advisory reviewed controlled trials and cohort data. The conclusion: replacing saturated fat with omega-6 PUFAs reduces LDL cholesterol and cardiovascular events. source: Sacks FM et al., Circulation, 2017, doi:10.1161/CIR.0000000000000510 That finding does not line up neatly with "seed oils are inflammatory."

The nuance: most of the protective-fat evidence comes from replacing saturated fat with polyunsaturated fat in controlled conditions, not from adding omega-6 on top of an already-high-fat diet. Population-level effects in people eating large amounts of both are not the same as the effects in a controlled trial.

For label-readers, the more actionable framing is NOVA status rather than omega-6 content. A refined seed oil in a packaged snack is a marker of ultra-processed food, and ultra-processed food as a dietary pattern is associated with negative health outcomes across large prospective cohort studies. Whether the specific causal mechanism is the omega-6 load or the broader dietary pattern is still an active research question. source: Monteiro CA et al., BMJ, 2019, doi:10.1136/bmj.l2451

Check food additives to avoid for other ingredients that tend to travel alongside refined seed oils in packaged food.

Which seed oils should you avoid, and which are fine?

The short answer: it depends on the extraction method, not the seed.

Pattern: "refined" means Group 4, "cold-pressed" or "expeller-pressed" is typically Group 2. When a label specifies no extraction method, assume Group 4.

At home, this distinction matters most for direct-use cooking (dressings, sauteing). In packaged food, refined seed oils appear in crackers, chips, bread, jarred sauces, and most commercial frying oil. Reading the ingredient list for "canola oil," "soybean oil," or "vegetable oil" (which is almost always soybean or canola in North American products) is a reliable proxy for NOVA 4 status.

What can you cook with instead?

The goal is not to avoid fat. It is to use fats that sit at NOVA Group 2 or lower for most cooking. Here is a practical guide by use case and smoke point.

A note on ghee: clarified butter is made by cooking butter to remove milk solids and water. That is a domestic-scale process, not an industrial one, and it places ghee in NOVA Group 2. source: Monteiro CA et al., Public Health Nutrition, 2018

The swap does not need to be perfect. Using refined sunflower oil occasionally is different from building a diet around it. The bigger lever is reducing packaged foods that list refined seed oils as a primary ingredient, since those tend to come bundled with other NOVA 4 markers.

FAQ

Are all seed oils ultra-processed?

No. The extraction method determines NOVA status, not the seed itself. Refined seed oils (canola, soybean, sunflower, safflower, corn) are NOVA Group 4 because they go through hexane solvent extraction, bleaching, and industrial deodorization at temperatures above 200°C. Cold-pressed or expeller-pressed versions of those same seeds skip the solvents and the high-temperature treatment, which puts them in NOVA Group 2, alongside butter and unrefined coconut oil. The label is your guide: "cold-pressed" or "expeller-pressed" signals Group 2; no extraction method listed typically signals Group 4. source: Monteiro CA et al., Public Health Nutrition, 2018

Is olive oil a seed oil?

No. Olive oil is pressed from the fruit of the olive tree, not the seed. Avocado oil (pressed from the fruit flesh) and coconut oil (pressed from coconut meat) are also fruit-derived, not seed-derived. These oils are often grouped with seed oils in wellness content because they are used similarly in cooking, but they are categorically different. Extra-virgin olive oil and unrefined avocado oil are both NOVA Group 2, produced by pressing fruit without industrial solvents or high-temperature deodorization.

Are cold-pressed seed oils still ultra-processed?

Generally no. Mechanical extraction without solvents puts most cold-pressed seed oils in NOVA Group 2, alongside butter and unrefined coconut oil. The key markers to look for on the label are "cold-pressed" or "expeller-pressed." If the bottle just says "sunflower oil" or "canola oil" with no extraction detail, assume it was refined using hexane (NOVA Group 4). Cold-pressed seed oils are harder to find and cost more because the yield is lower without solvents, so they are not typically the default shelf product. source: Monteiro CA et al., Public Health Nutrition, 2018

Is canola oil worse than other seed oils?

Not particularly, based on the refining process. All refined seed oils go through the same hexane extraction, bleaching, and deodorization steps that put them in NOVA Group 4. On the omega-6 question specifically, canola's ratio is actually lower than most other refined seed oils: roughly 2:1 omega-6 to omega-3, compared with roughly 71:1 for standard sunflower oil. source: USDA FoodData Central The refining process is the common thread across the category, and that is what matters for NOVA classification.

Do seed oils cause inflammation?

The mechanistic pathway exists: linoleic acid (the primary omega-6 in most seed oils) is a precursor to arachidonic acid, which feeds inflammatory signaling. But human trial evidence is mixed. The American Heart Association's 2017 Presidential Advisory on dietary fats found that replacing saturated fat with omega-6 polyunsaturated fat reduces cardiovascular events, which does not support a blanket "inflammatory" conclusion. Most major systematic reviews do not find a direct causal link between seed oil consumption and systemic inflammation at typical dietary amounts. The NOVA Group 4 classification, tied to the industrial refining process, is a more defensible reason to limit refined seed oils than the inflammation argument. source: Sacks FM et al., Circulation, 2017; Simopoulos AP, Biomedicine and Pharmacotherapy, 2002

Why did the EU restrict some seed-oil processing aids?

EFSA tightened limits on glycidyl esters and 3-MCPD fatty acid esters in 2016. Both compounds form during high-temperature deodorization, the last major step in the refining process. Glycidyl esters are metabolized to glycidol, a compound EFSA considers genotoxic. EFSA set tolerable intake levels and called for reformulation of deodorization conditions to reduce formation. Refined seed oils sold in the EU must comply with these limits. The refining process itself is still permitted; the regulatory action was about minimizing specific process contaminants, not banning the category. source: EFSA CONTAM Panel, EFSA Journal, 2016