Some olive oils have a better balance of two types of fats (omega-6 and omega-3) than others — Picual, Manzanilla, Cornicabra, and Sensation are in the healthy range, but Arbequina and its blends are way off.

All olive oils start out with a good balance of fats that lower bad cholesterol, but when you cook them really hot, that balance gets ruined — especially in oils that started with less of the good fats.

The green color of olive oil comes from chlorophyll, and the amount varies a lot between types — Picual and its blends are the greenest, Manzanilla is the least green.

When olive oil gets super hot, it starts forming gummy, big molecules called dimers — and the amount depends on the type of olive oil: blends with more Arbequina make way more than those with more Picual.

When olive oil gets really hot, it starts forming sticky, gummy molecules — and some types (like Armonia) make way more of them than others (like Picual).

Olive oil, which has lots of oleic acid, makes more of certain toxic aldehydes like 4-HNE and 2-decenal when heated than oils like soybean or palm.