Here's why:

* Salivary Amylase: Saliva contains an enzyme called salivary amylase, which starts the digestion of carbohydrates (starches) in the mouth. This enzyme breaks down complex carbohydrates into simpler sugars.

* Lubrication: Saliva also helps lubricate the food, making it easier to swallow.

While other bodily fluids are involved in digestion, saliva is the first to interact with food and initiate the chemical breakdown process.