What it is
Canola is a cultivar of rapeseed bred in the 1970s to remove erucic acid, which is toxic in quantity, and glucosinolates. The oil is hexane-extracted, bleached, and deodorized. At about 19% linoleic acid and 63% monounsaturated, its fatty-acid profile is much closer to olive oil than to the high-PUFA seed oils.
Why it's in your food
It's the default neutral, inexpensive cooking oil across North America, used for frying, baking, and dressings. Low cost and a bland flavor are why it's everywhere.
Why your biology objects
Only ~19% linoleic acid and ~63% monounsaturated, closer to olive oil's profile than to safflower's, so the OXLAM concern is real but far weaker. The more honest knock is the processing: deodorizing generates a small amount of trans fat (around 1 to 2%) before the bottle is opened. Better company than its label-mates; still a refined extract.
The ancestral lens
Rapeseed wasn't edible at scale until it was bred and refined into canola, so the oil itself is modern. That said, its monounsaturated-heavy profile is far less of a departure from ancestral fats than the high-linoleic seed oils are.
Dose & context
Because its linoleic acid is low, the oxidation concern is smaller than with safflower or soybean. The more honest issue is the refining: high-heat deodorizing produces a small amount of trans fat (roughly 1 to 2%) before you ever cook with it. Reused frying oil still degrades, as any oil does.
Label tricks
Often labeled “vegetable oil” or sold as simply “cooking oil.” “Cold-pressed” or “expeller-pressed” canola skips the solvent and high-heat steps, and is the less-processed version when you can find it.
What to reach for instead
Canola is already one of the milder choices. To go further, cold-pressed canola avoids the solvent and trans-fat issue, and traditional fats (olive oil, butter, tallow) avoid the refining entirely.
Straight answers
Is canola oil bad for you?
It's the mildest of the common seed oils: low in linoleic acid (~19%) and high in monounsaturated fat, closer to olive oil. The real knock is refining, which adds a small amount of trans fat (~1 to 2%), not a heavy PUFA load.
Is canola oil a seed oil?
Technically it's an oilseed oil from rapeseed. It's refined like the others, but its fatty-acid profile is much less polyunsaturated than safflower, sunflower, or soybean.
Is cold-pressed canola better?
Somewhat. Cold-pressed or expeller-pressed canola skips the solvent extraction and high-heat deodorizing, so it avoids the trans-fat issue of conventional canola.
What's the difference between canola and rapeseed oil?
Canola is a rapeseed cultivar bred to remove erucic acid. In Europe the same oil is often just called rapeseed oil.