During cooking, fatty acids can oxidize, meaning they react with oxygen and become damaged.
The double bonds in fatty acid molecules are mostly responsible for this.
For this reason, saturated fats — which have no double bonds — are resistant to high heat. Meanwhile, polyunsaturated fats — which have many double bonds — are more sensitive and can become damaged.
Olive oil contains mostly monounsaturated fatty acids, which have only one double bond. Therefore, olive oil is fairly resistant to moderate heat.
In one 2007 study, researchers heated extra virgin olive oil to 356°F (180°C) for 36 hours and found that the oil was highly resistant to damage.
