I accidentally bought something called pomace olive oil, which tasted horrible. Is that oil really made from olives? —D.L., Berkeley, Calif.

Yes, but it’s the lowest and cheapest grade of olive oil available. Pomace oil is made by applying heat, solvents, or hot water to the paste that’s left after higher grades of oil have been extracted. All that processing not only diminishes taste but removes many of the heart-healthy antioxidants found in higher grades, and it can add potentially cancer-causing compounds called polycyclic aromatic hydrocarbons. So skip the pomace in favor of virgin or extra-virgin olive oil.