Cellulose is formed in plants and consists of starch that is issued for energy conversion. However, in human beings, this passes undigested through bowels and cannot be broken down. This is because the human body does not have the right enzymes to disintegrate the beta acetal links that are required to break down and use cellulose for energy. The human digestive system lacks the ability to be able to break down monosaccharide bonds that are present in cellulose, and thus, cellulose passes through the bowels undigested.