Cellulose is a fiber found in fruits, vegetables, and other plant foods as part of a plant’s cell walls. It’s found in tree bark and a plant’s leaves. When you eat plant foods, you are consuming what is cellulose. But you may not be aware that cellulose fiber is also removed from plants to be used as an additive in many other foods as well as sold as supplements.
This article provides an overview of cellulose, where it’s commonly found, and whether or not it’s safe to consume.

What is cellulose?
Cellulose is made up of a series of sugar molecules linked together in a long chain. Since it is a fiber that makes up plant cell walls, it’s found in all plant foods. When you eat food that contains it, cellulose stays intact as it passes through your small intestine. Humans do not have the enzymes needed to break down cellulose.
Cellulose is also an insoluble fiber and does not dissolve in water. When consumed, insoluble fibers can help push food through the digestive system and support regular bowel movements. In addition to their role in healthy digestion, dietary fibers like cellulose may promote health in other ways. Studies suggest that high dietary fiber intake may reduce the risk of several diseases, including gastric cancer and heart disease.

Sources of cellulose
Fruits, vegetables, legumes, whole grains, nuts, seeds, and other plant foods contain varying amounts of cellulose. The skin of plant foods usually has more cellulose than the flesh. Celery, in particular, is very high in what is cellulose. If you have ever gotten stringy pieces from celery stuck between your teeth, then you have felt cellulose in action. Cellulose is also a common food additive. When used in this way, it is either taken from wood or waste from the production of plant foods, such as oat hulls or peanut and almond skins.
Cellulose may be added to shredded cheese or dried spice blends to prevent clumps. It’s also found in some ice creams and frozen yogurts, particularly low fat varieties, to help thicken or mix the product and provide thickness in the absence of fat. Bread products may be enriched with cellulose to boost their fiber content. In addition, cellulose can provide bulk to diet or low calorie foods, such as meal replacement shakes, to make them filling without increasing the total calories. It’s worth noting that dietary fibers in general are added to many food products, even things like yogurts and ground meats. If you’re interested in whether the products you buy contain cellulose or another added fiber, check the ingredients list.
Finally, cellulose is available in supplement form. Cellulose supplements often contain a modified version of cellulose that forms a gel in the digestive tract. Makers of these supplements claim that they help fill you up, lower calorie intake, and promote weight loss. However, it’s unclear whether cellulose supplements live up to their claims. A manufacturer-funded study on the weight loss effects of the cellulose supplement Plenity found that people who took the supplement lost more weight than those who took a placebo after 24 weeks. Still, more long-term studies are needed.

Safety of cellulose
Eating cellulose — especially from whole fruits and vegetables, grains, beans, and other plant foods — is generally considered safe. Any potential downsides of what is cellulose are related to side effects from the overconsumption of fiber. Current nutrition guidelines recommend that adults get at least 25 grams of fiber from foods per day but may need more or less depending on age, gender, and personal needs. If you eat a fiber-rich diet or are increasing your fiber intake, be sure to drink plenty of water to prevent uncomfortable side effects. Exercise can also help.
Those who need to follow a low fiber diet should limit cellulose intake. Individuals who have a health condition that affects the digestive system, such as inflammatory bowel disease (IBD), also need to watch out for cellulose in foods. Cellulose as a food additive is generally recognized as safe (GRAS) by the Food and Drug Administration (FDA). The levels of cellulose currently used in foods are not considered to be dangerous to humans. Keep in mind, however, that getting fiber from whole plant foods is usually better than getting it from additives or supplements. These foods provide many other beneficial nutrients and compounds in addition to fiber. Before adding cellulose supplements to your diet, it’s best to speak with a healthcare professional.