…or Why I NEVER Buy Reduced Fat Sour Cream!  From the always great Fooducate Blog:

Regular’s Ingredients [3 of them]:
Cultured pasteurized grade A cream and milk, enzymes.

Fat Free’s Ingredients [12]:
Cultured Lowfat Milk, Modified Corn Starch,Whey Protein Concentrate, Propylene Glycol Monoester, Artificial Color, Gelatin, Sodium Phosphate, Agar Gum, Xanthan Gum, Sodium Citrate, Locust Bean Gum, Vitamin A Palmitate.

When something as simple as Sour Cream is re-constructed in a science lab, something is definitely lost (and a helluva lot of chemicals gained).