What Are the Functions of Digestive Enzymes?

by Kirstin Hendrickson

About Kirstin Hendrickson

Kirstin Hendrickson is a writer, teacher, coach, athlete and author of the textbook "Chemistry In The World." She's been teaching and writing about health, wellness and nutrition for more than 10 years. She has a Bachelor of Science in zoology, a Bachelor of Science in psychology, a Master of Science in chemistry and a doctoral degree in bioorganic chemistry.

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Your digestive system breaks the food you eat down into small molecules that your intestines can absorb into the bloodstream. Two separate processes are at work. Mechanical digestion involves the physical breakdown of food into smaller chunks. This is what happens when you chew. Chemical digestion, which is the next phase, breaks food into smaller molecules. Digestive enzymes assist with chemical digestion.

Enzyme Basics

Enzymes are essentially large protein-based molecules that help chemical reactions take place faster than they otherwise would. Your body is in constant activity, even when you're sleeping. It requires a wide array of chemical reactions to remain alive and nearly all of them are enzyme-dependent. Digestive enzymes specifically help your body break down large nutrient molecules in your food into smaller nutrient molecules that your bowel can absorb. Once absorbed, these smaller nutrient molecules can be released in your bloodstream and carried to different organs for use.

Enzyme Production

Although most people think of the stomach as the organ of digestion, many other organs produce digestive enzymes. For instance, the salivary glands located in your mouth secrete a starch-digesting enzyme called amylase along with your saliva. Just like the cells that line your stomach, gut-lining cells also produce a small number of digestive enzymes. The pancreas, a digestive accessory organ, produces and discharges a large array of enzymes into the intestines.

Enzyme Types

Biochemists Mary Campbell, Ph.D. and Shawn Farrell, Ph.D. describe several digestive enzyme families. For instance, amylases digest starch, while proteases and lipases digest protein and fat, respectively. There are also a number of "specialist enzymes" that digest individual sugars. Sucrase, for instance, only digests sucrose. or table sugar. On the other hand, lactase only digests lactose, or milk sugar. Because your body does not have the appropriate enzymes to digest fiber, the latter leaves your bowel relatively unchanged.

Enzyme Specificity

An interesting feature of enzymes is that they're highly specific, explain Campbell and Farrell. For instance, sucrose and lactose have similar shapes and somewhat similar chemical compositions. Yet, your body needs two different enzymes in order to digest them. Lactose intolerance is a common disorder, which results from a lack the enzyme lactase. You may be unable to digest the lactose in dairy products even if your body produces sucrase and can digest sucrose.

Supplementation

A common misconception is that you can, or should, supplement your digestive tract with enzymes. However, there's no solid scientific evidence to support the effectiveness of enzyme supplementation. When you consume an enzyme, there's really no way for it to travel directly to the part of the body where it's supposed to function. The enzyme must first transit through the stomach, where it's treated like any other protein you consume -- it's digested and passed on to the small intestine, where it's absorbed and burned for energy.

References (3)

  • “Biochemistry”; Reginald Garrett, Ph.D. and Charles Grisham, Ph.D.; 2007
  • “Human Physiology”; Lauralee Sherwood, Ph.D.; 2004
  • “Biochemistry”; Mary Campbell, Ph.D. and Shawn Farrell, Ph.D.; 2005

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This article reflects the views of the writer and does not necessarily reflect the views of Jillian Michaels or JillianMichaels.com.