The acidity of the buttermilk is what reacts with the baking soda to help the bread rise — you'll see nice bubbles as you mix the ingredients.
That's because it interacts with
the acidity of the buttermilk, lemon juice and honey to create carbon dioxide (and thus makes the pancakes rise when you cook them).
Not exact matches
In
buttermilk biscuits, for example, alkaline baking soda is there to neutralize the
acidity in
buttermilk, which lets the baking powder in the recipe take care
of the rise.