Deficiency of vitamin B12 can occur in<unk><unk> Symptoms traditionally linked to<unk>  include bloating, diarrhea, and abdominal pain/discomfort. Steatorrhea may be seen in more severe cases.<unk><unk>  can cause a variety of symptoms, many of which are also found in other conditions, making the diagnosis challenging at times. Many of the symptoms are due to malabsorption of nutrients due to the effects of<unk> which either metabolize nutrients or cause inflammation of the<unk>  bowel, impairing absorption. The symptoms of<unk><unk>  include nausea, flatus, constipation, bloating, abdominal distension, abdominal pain or discomfort, diarrhea, fatigue, and weakness.<unk>  also causes an increased permeability of the<unk>  intestine. Some patients may lose weight. Children with<unk><unk>  may develop malnutrition and have difficulty attaining proper growth. Steatorrhea, a sticky type of diarrhea where fats are not properly absorbed and spill into the stool, may also occur. Patients with<unk><unk>  that is longstanding can develop complications of their illness as a result of malabsorption of nutrients. Laboratory test results may include elevated folate, and, less commonly, vitamin B12 deficiency or other nutritional deficiencies. Anemia may occur from a variety of mechanisms, as many of the nutrients involved in production of red blood cells are absorbed in the affected<unk>  bowel. Iron is absorbed in the more proximal parts of the<unk>  bowel, the duodenum and jejunum, and patients with malabsorption of iron can develop a microcytic anemia, with<unk>  red blood cells. Vitamin B12 is absorbed in the last part of the<unk>  bowel, the ileum, and patients who malabsorb vitamin B12 can develop a megaloblastic anemia with large red blood cells. Related conditions In recent years, several proposed links between<unk>  and other disorders have been made. However, the usual methodology of these studies involves the use of breath testing as an indirect investigation for<unk> . Breath testing has been criticized by some authors for being an imperfect test for<unk> , with multiple known false positives. Irritable bowel syndrome Some studies reported up to 80% of patients with irritable bowel syndrome (IBS) have<unk>  (using the hydrogen breath test). IBS-D is associated with elevated hydrogen numbers on breath tests while IBS-C is associated with elevated methane numbers on breath tests. Subsequent studies demonstrated statistically significant reduction in IBS symptoms following therapy for<unk> . Various mechanisms are involved in the development of diarrhea and IBS-D in<unk><unk> . First, the excessive<unk>  concentrations can cause direct inflammation of the<unk>  bowel cells, leading to an inflammatory diarrhea. The malabsorption of lipids, proteins and carbohydrates may cause poorly digestible products to enter into the colon. This can cause diarrhea by the osmotic drive of these molecules, but can also stimulate the secretory mechanisms of colonic cells, leading to a secretory diarrhea. There is a lack of consensus however, regarding the suggested link between IBS and<unk> . Other authors concluded that the abnormal breath results so common in IBS patients do not suggest<unk> , and state that "abnormal fermentation timing and dynamics of the breath test findings support a role for abnormal intestinal<unk>  distribution in IBS." There is general consensus that breath tests are abnormal in IBS; however, the disagreement lies in whether this is representative of<unk> .
Small intestinal bacterial overgrowth
Autoimmune gastrointestinal dysmotility
Intestinal neuronal dysplasia
Foreign body in alimentary tract
Exocrine pancreatic insufficiency
Glucose-galactose malabsorption
Fructose malabsorption
Food protein-induced enterocolitis syndrome