“Saturated” means “stable”
We now know that saturated fat is not the silent killer it was believed to be for the last half-century. In fact, saturation is not only not dangerous, it’s downright beneficial. Here comes the science: A fat is monounsaturated if it has one double bond within the fatty-acid chain. A fat is polyunsaturated if it has more than one. Saturated fats have no double bonds. What does that mean? The more double bonds, the more vulnerable the fat is to oxidation, which happens when the fat is exposed to light, air, and especially heat.
Expeller-pressed? Cold-pressed? Extra-virgin? What the...?
“The single thing to look for is refined (a.k.a. 'light') or unrefined,” says Dr. Shanahan. “This is the jackpot. You don’t need to refine something that has been extracted in a gentle way; you do need to refine something that’s been extracted in a harsh way, because the initial end-product is disgusting.” (Feel free to refer back to that canola oil video). Expeller-pressed is the same thing as cold-pressed, but when it comes to things like canola oil, which might say “cold-pressed” on the label, this is but the first in many, many steps of refinement. Extra-virgin means oil made from the first pressing — no refinement; you’re good to go.
When buying mono- and polyunsaturated oils like olive oil, walnut oil, and flaxseed oil, make sure you go for the dark, glass bottles. Unless you personally know your oil manufacturer, you have no idea how long those bottles have been sitting on shelves, exposed to light and heat — so the darker the glass, the better. The same goes for bringing your oils home. Keep your monos and polys in a cool, dark place away from your stove.