This doesn't answer your question, but you can also lighten tuna salad by substituting 1 tsp. regular mayo + 2 tsp. nonfat plain (NOT vanilla) yogurt for every tbs. of regular mayo. Light mayo may be lower in fat than regular mayo, but it has corn starch, xanthan gum, phosphoric acid, and all sorts of other fillers and additives that regular mayo doesn't have. Besides, it tastes like
. (To me, at least.