Seed oils are cooking oils extracted from the seeds of plants, as opposed to oils pressed from the fruit (like olive oil or coconut oil) or rendered from animal fat (like butter or lard). The eight oils most commonly discussed as seed oils are canola, soybean, safflower, corn, cottonseed, grapeseed, rice bran, and peanut oil. Sunflower oil also belongs squarely in this category. Together, these oils dominate packaged foods, restaurant kitchens, and fast food fryers worldwide.
The Core List of Seed Oils
Here are the oils that fall under the seed oil label, grouped by how commonly you’ll encounter them:
- Soybean oil: The most widely consumed seed oil in the United States. It shows up in everything from salad dressings to frozen meals. About 54% of its fat is linoleic acid, an omega-6 polyunsaturated fat.
- Canola oil: Made from rapeseed bred to contain very low levels of erucic acid (no more than 2% under federal regulations). It’s marketed as a heart-healthy option because of its relatively high monounsaturated fat content.
- Corn oil: Extracted from the germ of corn kernels. It’s a staple frying oil with a smoke point around 446 to 460°F.
- Sunflower oil: Conventional versions are high in omega-6 fats, though newer “high oleic” varieties have been bred to contain as little as 6% linoleic acid, shifting the fat profile closer to olive oil.
- Cottonseed oil: Originally a byproduct of the cotton industry, it became one of the first mass-produced cooking oils in the U.S. Smoke point sits around 428 to 446°F.
- Safflower oil: Similar to sunflower oil in its fatty acid makeup. Like sunflower, it now comes in high-oleic versions.
- Grapeseed oil: A byproduct of winemaking. It has the highest omega-6 content of any common cooking oil, with a single tablespoon delivering nearly 9,500 mg of omega-6 polyunsaturated fat.
- Rice bran oil: Extracted from the outer layer of rice grains. It’s popular in Asian cooking and has a mild flavor.
- Peanut oil: Technically a legume oil, but consistently grouped with seed oils because of its similar extraction process and fatty acid profile.
What Makes Them Different From Other Cooking Oils
The distinction between seed oils and other fats comes down to the source and, often, how they’re processed. Olive oil is pressed from the flesh of a fruit. Coconut oil comes from the meat of a coconut. Butter is churned from cream. Seed oils, by contrast, come from small, hard seeds that don’t give up their fat easily, which historically required more aggressive extraction methods.
Most commercial seed oils are produced using solvent extraction. Oilseeds are flaked, then either submerged in a chemical solvent or sprayed with it to dissolve the fat out. The mixture of oil and solvent then passes through distillation columns and steam stripping to remove the solvent. After extraction, the oil typically goes through additional refining steps to remove impurities, adjust color, and neutralize flavor. The result is a clear, neutral-tasting oil with a long shelf life.
Cold-pressed or expeller-pressed versions of these same oils do exist. Mechanical pressing uses a screw press that generates pressure and friction to squeeze oil from the seeds without chemical solvents. These versions retain more of the original antioxidants, including vitamin E compounds called tocopherols and plant-based phenolic compounds. The tradeoff is a shorter shelf life, stronger flavor, and higher price.
The Omega-6 Question
The main nutritional concern around seed oils centers on their high concentration of omega-6 polyunsaturated fats, specifically linoleic acid. Conventional soybean oil is about 54% linoleic acid. Grapeseed oil is even higher. The worry is that modern diets already contain far more omega-6 fat than omega-3 fat, and that this imbalance could promote inflammation.
The clinical evidence is more nuanced than the online debate suggests. A large meta-analysis published in the American Heart Association’s journal Circulation found that higher linoleic acid intake was associated with a 15% lower risk of coronary heart disease events and a 21% lower risk of dying from heart disease, comparing people who ate the most to those who ate the least. Replacing 5% of daily calories from saturated fat with linoleic acid was linked to a 9% reduction in heart disease events. These findings support mainstream dietary guidelines that recommend replacing saturated fat with polyunsaturated fat.
That said, these studies look at overall intake patterns, not at what happens when oils are heated repeatedly in deep fryers or consumed in large quantities through ultra-processed foods. The context in which you consume seed oils matters as much as the oils themselves.
How Heating Changes Seed Oils
Polyunsaturated fats are less chemically stable than saturated or monounsaturated fats. Their molecular structure includes multiple double bonds that react easily with oxygen, especially at high temperatures. When seed oils are heated, this oxidation process generates a range of breakdown products, including aldehydes and other reactive compounds. The higher the polyunsaturated fat content and the longer the oil is heated, the more of these compounds form.
Refined seed oils do have reasonably high smoke points, which is why they’re so popular for frying. Soybean oil can handle temperatures up to about 453°F, and corn oil reaches 446 to 460°F before smoking. But smoke point alone doesn’t tell you how stable an oil is during prolonged cooking. An oil can begin producing oxidation byproducts well before it starts to visibly smoke, particularly when it’s reused multiple times.
Where Seed Oils Show Up in Your Diet
Global production of the major vegetable oils (palm, soybean, sunflower, and rapeseed) reached a supply forecast of 227.1 million metric tons for the 2024/25 marketing year. Soybean oil alone accounts for roughly 14 billion pounds of food, feed, and industrial use in the U.S., with another 13 billion pounds going to biofuel production.
If you eat packaged food, you’re almost certainly consuming seed oils. They’re the default fat in chips, crackers, cookies, frozen meals, salad dressings, mayonnaise, and most restaurant cooking. Soybean oil is the single most common oil in the American food supply, partly because soybeans are cheap and abundant. Canola is the second most common. Reading ingredient labels is the most reliable way to identify which oils are in the foods you buy.
High-Oleic Varieties Are Changing the Picture
Plant breeders have developed new versions of several seed oils that flip the fatty acid profile. High-oleic soybean oil contains just 1% linoleic acid, compared to 54% in the conventional version. High-oleic sunflower oil drops to about 6% linoleic acid. These oils are much higher in oleic acid, the same monounsaturated fat that makes olive oil relatively stable for cooking.
High-oleic seed oils are increasingly used by food manufacturers and restaurant chains looking to reduce polyunsaturated fat in their products. They offer the same neutral flavor and high smoke points as conventional seed oils but with improved oxidative stability. If your concern about seed oils is specifically about omega-6 content, high-oleic versions address that directly, though they’re not always labeled prominently on packaging. Look for “high oleic” in the ingredient list, typically before sunflower or soybean oil.