What Are Seed Oils? Complete List and Guide

The Eight Common Seed Oils

Seed oils are exactly what they sound like: oils extracted from the seeds of plants. That definition technically covers a lot of ground (olive oil comes from the fruit of the olive, not its seed), but when people talk about "seed oils" in the context of health, they mean a specific group of industrially processed vegetable oils. These eight are the ones you will encounter most often in packaged foods, restaurant kitchens, and grocery store shelves.

For a broader overview of why these oils matter, see our complete guide to seed oils.

• Canola oil (rapeseed oil) . Derived from a specially bred variety of rapeseed developed in Canada in the 1970s (the name comes from "Canadian oil, low acid"). It contains about 21% omega-6 linoleic acid and is the most commonly used cooking oil in North America. You will find it in nearly every restaurant fryer and most packaged baked goods.
• Soybean oil . The single most consumed oil in the United States, accounting for roughly 60% of all vegetable oil consumption. It is a byproduct of the massive soy protein industry. Soybean oil contains around 51% omega-6 linoleic acid and appears in everything from salad dressings to infant formula.
• Corn oil . Extracted from the germ of corn kernels, this oil is a byproduct of corn milling and ethanol production. It contains about 54% omega-6 linoleic acid. Corn oil became popular in the mid-20th century when Mazola marketed it as a "heart-healthy" alternative to animal fats.
• Sunflower oil . Pressed from sunflower seeds, this oil is widely used in snack foods, chips, and crackers. Standard sunflower oil contains around 68% omega-6 linoleic acid, making it one of the highest omega-6 oils available. High-oleic varieties exist with much lower omega-6 content (around 4%), but the standard version dominates commercial use.
• Safflower oil . Made from the seeds of the safflower plant, a thistle-like crop grown primarily in arid climates. Standard safflower oil has the highest omega-6 content of any common cooking oil at roughly 75% linoleic acid. Like sunflower oil, high-oleic versions are available but less common in processed foods.
• Cottonseed oil . This was the original industrial seed oil in America. Cottonseed is a byproduct of the cotton industry, and before the 1900s the oil was considered industrial waste. It contains about 52% omega-6 linoleic acid. You will still find it in many packaged snack foods and some restaurant fryers.
• Grapeseed oil . Extracted from the seeds left over after winemaking, grapeseed oil is often marketed as a premium or "natural" cooking oil. Despite its upscale image, it contains roughly 70% omega-6 linoleic acid and goes through the same solvent extraction and refining process as other seed oils.
• Rice bran oil . Popular in Asian cooking, particularly in Japan, India, and China, this oil is extracted from the outer bran layer of rice grains. It contains about 33% omega-6 linoleic acid. Rice bran oil has a high smoke point, which makes it popular for deep frying.

How Seed Oils Are Made

Seeds are not naturally oily. Unlike olives or coconuts, which release their oil with simple mechanical pressure, most seeds hold onto their fats tightly. Getting the oil out requires an intensive industrial process that would be unrecognizable to anyone who has ever pressed an olive.

The process typically follows these steps:

• Cleaning and conditioning. The seeds are cleaned of debris and heated to about 120-180°F to soften them and make the oil easier to extract.
• Mechanical pressing. The seeds pass through an expeller press, a screw-type machine that crushes them under high pressure. This removes some oil, but a significant amount remains trapped in the seed meal.
• Solvent extraction. To get the remaining oil, the pressed seed meal is washed with hexane, a petroleum-derived chemical solvent. Hexane dissolves the oil, which is then separated from the solvent through evaporation. Trace amounts of hexane can remain in the finished product.
• Degumming. The crude oil contains phospholipids, proteins, and other compounds that make it cloudy and unstable. These are removed by mixing the oil with water or acid, then centrifuging out the resulting gums.
• Refining (neutralization). The oil is treated with sodium hydroxide (lye) to remove free fatty acids that would cause off-flavors and reduce shelf life.
• Bleaching. Despite the name, this step uses clay filters rather than bleach. The oil passes through activated clay or diatomaceous earth to remove pigments, residual soap from the refining step, and oxidation products.
• Deodorizing. The final step involves heating the oil to 450-500°F under a vacuum and injecting steam. This strips out volatile compounds responsible for unpleasant smells and tastes. It also removes almost all remaining vitamin E and other natural antioxidants.

Compare this to extra virgin olive oil, which is produced by mechanically crushing olives and separating the oil from the water. No solvents, no bleaching, no deodorizing. The same goes for butter (churned from cream) or tallow (rendered from beef fat). These traditional fats require only physical processes that humans have used for centuries.

The deodorizing step is especially worth noting. By the time a seed oil leaves the factory, it has been stripped of virtually all flavor, color, and aroma. This is by design. A neutral-tasting oil is more versatile for food manufacturers, but it also means the oil has lost most of the minor compounds (tocopherols, polyphenols, carotenoids) that might have provided some nutritional value.

A Brief History

For most of human history, people cooked with animal fats (butter, lard, tallow) and a small number of fruit-derived oils (olive, coconut, palm). Seed oils simply did not exist in the food supply because the technology to extract them at scale had not been invented.

That changed in the late 1800s. Cottonseed, previously discarded as waste from cotton production, became the first seed to be industrially pressed for oil. By the 1890s, cottonseed oil was being used in soap, candles, and eventually as a cheap adulterant in lard and olive oil.

The real turning point came in 1911, when Procter & Gamble introduced Crisco, a hydrogenated cottonseed oil product marketed as a modern, clean alternative to animal fats. Crisco was the first mass-market product to position a seed oil as something desirable rather than a cheap substitute. The company distributed free cookbooks and ran advertising campaigns that framed lard and butter as old-fashioned.

Soybean oil entered the picture during World War II. Wartime demand for glycerin (used in explosives) led to a massive expansion of soybean processing. After the war ended, the industry had enormous production capacity and needed new markets. Soybean oil quickly became the cheapest cooking oil available.

The numbers tell a dramatic story. In 1909, Americans consumed an estimated 2 grams of soybean oil per person per day. By 1999, that figure had risen to roughly 26 grams per person per day. Total added fat consumption increased by about 63% over the 20th century, with virtually all of that increase coming from seed oils.

Canola oil arrived later, in the 1980s and 1990s, after Canadian researchers bred a low-erucic-acid variety of rapeseed that was considered safe for food use. It quickly gained market share due to its neutral flavor and relatively low cost.

By the 2000s, seed oils had become so deeply embedded in the food system that avoiding them required deliberate effort. They are the default cooking oil in virtually every restaurant, the base of nearly all commercial salad dressings, and a standard ingredient in bread, crackers, chips, frozen meals, and even "health foods" like protein bars and plant-based milks.

Seed Oils vs. Traditional Fats

One of the clearest ways to understand seed oils is to compare them with the fats humans consumed for thousands of years before industrial processing. The differences in source, processing method, omega-6 content, and historical use are significant.

The pattern is clear. Traditional fats tend to be low in omega-6, require minimal processing, and have track records spanning millennia. Seed oils are high in omega-6, require extensive industrial processing, and have been in the food supply for less than a century. The health implications of this omega-6 shift are a subject of growing research and debate.

Why Seed Oils Became Dominant

Seed oils did not take over the food supply because they taste better or because people demanded them. Their rise was driven by a combination of economics, industry strategy, and institutional influence.

Cost. Seed oils are extraordinarily cheap to produce. Soybeans, corn, canola, and cotton are among the most heavily subsidized crops in the United States. The oils are often byproducts of other processes (soy protein extraction, corn ethanol production, cotton fiber harvesting), which means the raw materials are nearly free. A gallon of soybean oil costs a fraction of what olive oil or butter costs. For restaurants and food manufacturers operating on thin margins, the economics are compelling.

Shelf life and versatility. The heavy refining process that strips seed oils of flavor and aroma also makes them remarkably shelf-stable. They do not go rancid as quickly as unrefined oils. They have neutral flavors that work in any application. They have high smoke points suitable for deep frying. For food manufacturers who need an oil that can sit in a warehouse, survive shipping, and not affect the taste of a product, seed oils are the path of least resistance.

Industry influence on dietary guidelines. The story of how seed oils became officially "healthy" is tangled up with corporate funding and institutional politics. In the 1960s, the sugar industry funded research that shifted blame for heart disease from sugar to dietary fat, specifically saturated fat. This set the stage for decades of dietary advice that encouraged people to replace butter, lard, and tallow with vegetable oils.

The American Heart Association (AHA) has recommended replacing saturated fats with polyunsaturated vegetable oils since 1961. Notably, Procter & Gamble (the maker of Crisco) made a major early donation to the AHA in 1948, helping to transform it from a small professional society into a national powerhouse. The AHA continues to recommend seed oils today, and its Heart-Check certification program has approved products containing canola and soybean oil.

The displacement of animal fats. As dietary guidelines pushed consumers away from saturated fat, the market for traditional cooking fats collapsed. McDonald's famously switched from beef tallow to vegetable oil for its french fries in 1990, responding to pressure from health advocates. Restaurants, school cafeterias, and home cooks followed. By the late 1990s, seed oils had almost completely replaced animal fats in the American food supply.

Scale begets scale. Once seed oils dominated the supply chain, the infrastructure built around them made alternatives even more expensive by comparison. Restaurant supply companies stock seed oils by default. Food-service equipment is designed around their properties. Switching to tallow or olive oil requires not just paying more per gallon but often redesigning supply chains, recipes, and kitchen workflows. This lock-in effect means that even restaurants that want to switch face real practical barriers.

The result is a food environment where seed oils are everywhere. Reading ingredient labels and choosing restaurants carefully are two of the most effective strategies for reducing your intake. Understanding what these oils are, where they come from, and how they ended up in everything is the first step.