Why we avoid it:

About 90% of its calories come from fat, at least half of which is saturated. If you were told to limit your saturated fat intake and to choose low-fat dairy products, you probably avoided sour cream.

Why we should eat it:

Sour cream is made by introducing certain types of lactic-acid bacteria to regular cream and allowing it to ferment. The saturated fat content isn’t that bad. If you top your baked potato with a dollop of full-fat sour cream — about 2 tablespoons — you’ll only be adding 2 grams of saturated fat, less than you’d get from drinking a 12-ounce glass of 2% milk. You’ll also be adding a good source of calcium, protein, vitamin B12 and phosphorus. Skip the low-fat versions. The full-fat stuff tastes better, doesn’t have added carbohydrates and doesn’t contain dangerous trans fat.