Ask Tufts Experts

Comparing ingredients lists for processed peanut butters (like Skippy and Jif) and natural peanut butter (the kind you have to stir to mix the oil and the solids), I see that the processed kinds are made with “partially hydrogenated vegetable oil,” which means they contain cholesterol-raising trans fatty acids. How many grams of trans fatty acids does processed peanut butter have?

None. The hydrogenation that occurs is really more “complete” than “partial,” and when that happens, fat turns to saturated fat rather than trans fatty acids. Of course, saturated fat raises blood cholesterol, too. But in the case of peanut butter, the hydrogenation process changes only a small amount of oil in the product. In fact, it raises the saturated fat in a 2-tablespoon serving by only 1 gram, bringing the level to 3 grams as opposed to 2 in natural peanut butter. Most of the fat in peanut butter remains monounsaturated.

My husband says a baked sweet potato is better for you. I say a baked white potato is. Who’s right?

You both are. The sweet potato has it over the white one in terms of beta-carotene, vitamin C, folate, calcium, and manganese. But the white potato trumps the orange one for protein, niacin, vitamin B6, potassium, and iron, with a little extra copper thrown in for good measure. So don’t get hung up on which vegetable is “better.” Switch around according to your taste buds.