What does the German saying “Sauer macht lustig” mean?

Squeezing lemon into the lentil salad, grandma explains her reasoning with a line straight out of an old German saying: Sauer macht lustig — “sour makes you cheerful/funny.” It’s a proverb traced back at least to Martin Luther in 1523, and it’s exactly the kind of folksy wisdom grandparents reach for while cooking — half joke, half genuine kitchen advice.

The saying’s original wording was actually Sauer macht gelüstig — “sour whets the appetite” — since acidic foods stimulate saliva and digestion, making you hungrier. Over time gelüstig shifted to lustig (“funny/cheerful”), giving the proverb its modern, more playful meaning. Either reading fits this scene: a squeeze of lemon that makes the salad — and the mood — a little brighter.