Inflammatory bowel disease (IBD, Inflammatory bowel disease) is not a single disease but a group of chronic disorders of the small and large intestines causing inflammation. In the United States, approximately 2 million people have some form of IBD. One of the most common types of IBD is ulcerative colitis. This disease causes ulceration and inflammation of the inner lining of the rectum and large intestine and is considered incurable.

Ulcerative colitis involves symptoms of diarrhea, negative stool cultures, and typical findings of superficial ulcerations, vascular patterns of distorted mucosal granularity and exudate. From these data, we can calculate an Activity Index of Disease (ICD Disease Activity Index).

Since studies in animals and humans have suggested that Chlorella pyrenoidosa in the diet has many beneficial effects on wound healing and immune reactions, the authors hypothesized that supplementation may be effective in relieving symptoms ulcerative colitis. And this was indeed the case: not only decreased DAI, but also in their own evaluations of the subjects of their symptoms (Merchant and Andre, 2001).