How Digestive Enzymes Work on Food

The nutrients you need for good health are locked away in the foods you eat so it's your digestive system's job to set them free. By the process of digestion, food is broken down into tiny little bits so the nutrients can be released and absorbed through the walls of the small intestine.

It would take a very long time for the food just to fall apart on its own, so special digestive enzymes are necessary to speed up the process. These enzymes don't just attack all food; they're actually quite specialized. Some go after carbohydrates, some break fats down, and others break proteins apart. Each enzyme has a specific action.

The Main Digestive Enzymes

Here are the main digestive enzymes, where they're made, and what they do:

Salivary Amylase

Made and released by salivary glands in your mouth. Salivary amylase breaks starch down into shorter chains of glucose molecules. It works in the mouth, but once food reaches your stomach, the acidic pH deactivates it.

Lingual Lipase

Made by Ebner's glands in your tongue and the back of your mouth. Lingual lipase works in the mouth and the stomach. It breaks medium and long-chain triacylglycerols (fats) into smaller bits.

Pepsin

The primary digestive enzyme in the stomach. Chief cells in the stomach make pepsinogen, which is converted to pepsin by the acid environment of the stomach. Pepsin breaks proteins down into polypeptides and amino acids.

Gastric Lipase

Another digestive enzyme secreted by chief cells in the stomach. It's similar to lingual lipase, but it breaks down short and medium-chain triacylglycerols. Lingual and gastric lipase are most important during infancy because they break down the fats found in mother's milk.

Pancreatic Amylase

This enzyme is made by the pancreas and secreted into the small intestine. Pancreatic amylase breaks starches into short chains of glucose and maltose.

Pancreatic Lipase

Another pancreatic enzyme made and secreted into the small intestine. Pancreatic lipase breaks triacylglycerols into diacylglycerols, monoacylglycerols, and free fatty acids and glycerol.

Trypsin and Chymotrypsin

These two pancreatic enzymes break down proteins. They break proteins and polypeptides into shorter polypeptides.

Peptidases

These enzymes are made from the pancreas and secreted into the small intestine. The peptidases work in the small intestine and pick up where the trypsins and pepsin left off to reduce polypeptides to individual amino acids.

Sugar Enzymes

These four enzymes are all made and released by cells in the lining of the small intestine. Each enzyme works on a different type of sugar:

• Dextrinase: Breaks chains of glucose into individual glucose units
• Lactase: This one breaks lactose (milk sugar) down into glucose and galactose
• Maltase: Breaks maltose into glucose
• Sucrase: Breaks sucrose (table sugar) into glucose and fructose