What macromolecule is the only one to start digestion in the mouth?

The only macromolecule that begins digestion in the mouth is carbohydrates. Salivary amylase, an enzyme found in saliva, initiates the breakdown of starches into simpler sugars as food is chewed. This process allows for the preliminary digestion of carbohydrates before they continue to the stomach and intestines for further breakdown and absorption.