What Is Cellulase? The Enzyme That Breaks Down Plant Fiber

Cellulase is an enzyme that breaks down cellulose, the main fiber in plant cell walls. Your body does not make cellulase, so cellulose passes through your small intestine undigested (1,2). In your body, cellulase has no natural job. A cellulase supplement adds the enzyme to your meal, where it helps break down plant cell walls and fibers from plant-based foods.*

This page is part of our guide to digestive enzymes. Below you will learn what cellulase is, what happens to fiber in your body, which foods contain cellulose, and where you find cellulase in our products.

written and reviewed by Anouk Martini (registered dietician)

Knowledge bank

In short

Cellulase is an enzyme that breaks down cellulose, a fiber in plant cell walls (2).
Your body does not make cellulase. Fiber resists digestion by human enzymes (1,2).
Bacteria in your large intestine may break down part of the fiber (2,3).
Cellulase is in our product Enzymix.

What is cellulase?

Cellulose is a long chain of glucose units and the main structural part of plant cell walls (2). Fruits, vegetables, whole grains, legumes, and nuts all contain it. Cellulase is the enzyme that can split those chains.

Dietary fiber is the part of plant cell walls that resists digestion by human enzymes (1). Unlike starch, cellulose cannot be digested in your small intestine, because the enzymes needed are not present (2). That is why humans do not use cellulose as a source of energy.

What does cellulase do in the body?

In your body, cellulase has no natural role, because humans do not make it. This is what happens to cellulose instead:

In your mouth, stomach, and small intestine. Your own enzymes digest starch, protein, and fat, but not cellulose (1,2).
In your large intestine. Bacteria may break down part of the fiber that arrives there (2,3).
The rest leaves your body. Parts of food that are not digested become stool (3).

When you take a cellulase supplement with a meal, the enzyme adds a tool your body does not have. Cellulase helps break down plant cell walls and fibers from plant-based foods.* Fiber is still a valuable part of a balanced diet.

Which foods contain cellulose?

Cellulose is in the cell walls of all plants. Foods that contain a lot of it include:

Vegetables, especially raw vegetables and leafy greens
Fruit with edible skins and seeds
Whole grains and bran
Legumes such as beans and lentils
Nuts and seeds

When might extra cellulase help?

Some people take a cellulase supplement with fiber-rich, plant-based meals, such as big salads, raw vegetables, whole grains, or legumes. Age, diet, lifestyle, and stress can all affect how well digestion works, and so do the size and type of a meal.

Not sure whether a supplement fits you? Talk to a doctor or dietitian.

Where is cellulase in our products?

Cellulase is in one Intoleran product:

Enzymix is a blend of nine digestive enzymes that support the breakdown of carbohydrates, proteins, fats, lactose, and plant fibers.* Its cellulase (500 CU) helps break down plant cell walls and fibers from plant-based foods.* Enzymix is formulated with nine non-animal-derived enzymes. The capsules can be opened and mixed with food, so Enzymix suits children ages 2 and up. It is suitable for vegetarians and vegans and free of gluten and soy.

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

Not sure which enzyme you need?

Digestive enzymes each have their own job. Answer a few questions in our supplement advisor and see which products fit your situation. You can also ask our dietitians a question.

When should you talk to a doctor or dietitian?

Do your symptoms persist, are you losing weight without trying, or are you cutting out more and more foods? Talk to your doctor or a dietitian. A supplement does not replace medical advice.

Plant foods contain more than fiber. Alpha-galactosidase works on galactans, such as the raffinose in beans, and amylase works on starch. See all of our digestive enzymes.

Sources

National Institute of Diabetes and Digestive and Kidney Diseases. Your digestive system & how it works [Internet]. Bethesda (MD): National Institute of Diabetes and Digestive and Kidney Diseases; last reviewed 2017 Dec. Available from: https://www.niddk.nih.gov/health-information/digestive-diseases/digestive-system-how-it-works
Dietary fiber [MeSH scope note, National Library of Medicine] [Internet]. In: Descriptors in Health Sciences (DeCS). São Paulo: BIREME/PAHO/WHO. Available from: https://decs.bvsalud.org/en/ths/resource/?id=23102
Science Learning Hub. Dietary fibre [Internet]. Hamilton (NZ): University of Waikato, Science Learning Hub. Available from: https://www.sciencelearn.org.nz/resources/536-dietary-fibre