Vegetable oils have been recommended as a healthier alternative to saturated animal fats for decades. But emerging data suggest the opposite—at least when it comes to the heavily refined, denatured seed oils most people are consuming.
Most vegetable oils consist primarily of monounsaturated and polyunsaturated fats that are more prone to oxidation than saturated animal fats. To explain that in molecular detail, the susceptibility of individual fatty acids to oxidation depends on their length and the presence or absence of double bonds.