Corn oil

What it is

Corn oil is extracted from the germ separated during corn milling, usually with hexane, then refined and deodorized. At about 55% linoleic acid it sits in the middle of the seed-oil range. Like the others, it exists because it's a cheap byproduct of a commodity crop.

Why it's in your food

It's a workhorse frying oil for restaurants and fast food and a base for margarine and packaged baked goods. Subsidized corn keeps it cheap, which is the whole reason it's used at this scale.

Why your biology objects

~55% linoleic acid, the same ω-6 peroxidation story, mid-pack on dose. Like the others it's solvent-extracted and deodorized, so it arrives with some oxidation already done before your pan adds more.

The ancestral lens

Corn germ doesn't give up its oil without industrial pressing and solvent extraction, so this is a recent food. It delivers linoleic acid at the modern scale (near 20% of calories) that a diet of whole foods never approached.

Dose & context

Deep frying is the worst case for a polyunsaturated oil: high heat, repeated reuse, and hours of air exposure all speed oxidation. Restaurant fryer oil is often corn oil reused across a day, which is when the most oxidation products form.

Label tricks

Often hidden inside “vegetable oil” on a label. Margarine and shortening made from it carry a “plant-based” or “cholesterol-free” framing that says nothing about the oxidized fat.

What to reach for instead

For frying at home, stable fats like tallow, ghee, or avocado oil don't degrade the way corn oil does. Beef tallow is, in fact, what many fryers used before seed oils replaced it on cost.