Saliva contains an enzyme that primarily acts upon which type of nutrient?

Saliva contains the enzyme amylase, which primarily acts on starches. Amylase breaks down complex carbohydrates into simpler sugars, initiating the process of carbohydrate digestion in the mouth. This enzymatic action is crucial because it begins the digestive process even before food reaches the stomach.

Starches, being polysaccharides, are more complex molecules that need to be broken down into monosaccharides or disaccharides for absorption in the body. Saliva's ability to start this process makes it essential to the overall digestion of carbohydrates.

In contrast, the other nutrient types listed—fats, proteins, and vitamins—are not primarily broken down by the enzymes found in saliva. Fat digestion primarily occurs in the stomach and small intestine with the help of bile and lipases, while protein digestion is initiated by stomach acids and enzymes like pepsin. Vitamins do not require enzymatic breakdown for digestion, as they are typically absorbed in their original form. This distinction highlights the specific role of saliva and amylase in the digestive process, particularly concerning starches.