The digestive tract consists of a group of hollow organs, including the mouth, esophagus, stomach, small intestine, large intestine, rectum and anus, which function to absorb fluids and nutrients into the bloodstream. The solid organs of the digestive system, including the liver, pancreas and gall bladder, produce a variety of enzymes that aid in the breakdown of food particles. Several conditions and diseases that cause a deficiency in substances necessary for digestion result in diarrhea.
Lactase Deficiency
Lactose, the sugar found in milk and milk products, is a complex sugar known as a disaccharide that consists of two simple sugars bound together, which in the case of lactose includes glucose linked to galactose. Due to their size, the body cannot absorb disaccharides, so the digestive system produces enzymes such as lactase to break the complex sugar into its simple sugar parts.
The small intestine functions to absorb nutrients and remove excess fluid from the partially digested contents, and also contains enzymes, including lactase. Some people fail to produce enough lactase, a condition known as lactase deficiency, which leads to a condition known as lactose intolerance. Because lactose cannot be absorbed, lactose intolerance causes abdominal pain, bloating, gas and diarrhea.
Pancreatic Enzyme Deficiency
The pancreas, a small organ located next to the small intestine, produces and secretes digestive enzymes that travel through the pancreatic duct into the small intestine. The body needs these enzymes, which include proteolytic enzymes to break down proteins, lipases to break down fats and amylases to break down carbohydrates, to make the food molecules small enough for absorption.
Inflammation of the pancreas, a condition known as pancreatitis, damages the pancreas and inhibits the production of the enzymes. Pancreatitis may either be acute and have a sudden onset, or chronic, and often occurs due to chronic alcohol consumption, the presence of gallstones, abdominal trauma, and damage from certain medications or tumors, according to the National Digestive Diseases Information Clearinghouse. Pancreatic enzyme deficiency inhibits the absorption of substances, leading to diarrhea, abdominal bloating and gas, as described by The Merck Manuals Online Medical Library.
Protective Bacteria Deficiency
The digestive tract contains many different types of bacteria, including beneficial bacteria and harmful bacteria. The beneficial bacteria help keep the harmful bacteria under control, therefore keeping the digestive system healthy.
Taking antibiotics, such as cephalosporin, clindamycin, erythromycin, penicillin and tetracycline, can interrupt this delicate balance within the digestive system. As antibiotics kill beneficial bacteria, the resulting deficiency in the protective bacteria allows the harmful bacteria to multiply and produce toxins that cause inflammation of the digestive tract. This causes diarrhea, a condition known as antibiotic-associated diarrhea, according to MayoClinic.com.
References
- National Digestive Diseases Information Clearinghouse: Lactose Intolerance
- Food Reactions: Lactose, Lactase and the Transport Mechanism
- National Digestive Diseases Information Clearinghouse: Pancreatitis
- The Merck Manuals Online Medical Library: Malabsorption Syndromes
- Mayo Clinic: Antibiotic-Associated Diarrhea
