Because the digestive system has a lot of reserve built into it, aging has less effect on its function than it does on the function of other organ systems. Nonetheless, aging is a factor in several digestive system disorders. In particular, older adults are more likely to develop diverticulosis Diverticulosis of the Large Intestine Diverticulosis is the presence of one or more balloon-like sacs (diverticula), usually in the large intestine (colon). The cause of diverticulosis is unknown but may be related to diet, a sedentary... read more and to have digestive tract disorders (for example, constipation Constipation in Adults Constipation is difficult or infrequent bowel movements, hard stool, or a feeling that the rectum is not totally empty after a bowel movement (incomplete evacuation). (See also Constipation... read more —see Large intestine and rectum Large intestine and rectum Because the digestive system has a lot of reserve built into it, aging has less effect on its function than it does on the function of other organ systems. Nonetheless, aging is a factor in... read more ) as a side effect of taking certain drugs.
(See also Overview of the Digestive System Overview of the Digestive System The digestive system, which extends from the mouth to the anus, is responsible for receiving food, breaking it down into nutrients (a process called digestion), absorbing the nutrients into... read more .)
With age, the strength of esophageal contractions Throat and Esophagus The throat (pharynx) lies behind and below the mouth. When food and fluids leave the mouth, they pass through the throat. Swallowing of food and fluids begins voluntarily and continues automatically... read more and the tension in the upper esophageal sphincter decrease (called presbyesophagus), but the movement of food is not impaired by these changes. However, some older adults can be affected by diseases that interfere with esophageal contractions.
With age, the stomach lining's capacity to resist damage decreases, which in turn may increase the risk of peptic ulcer disease Peptic Ulcer Disease A peptic ulcer is a round or oval sore where the lining of the stomach or duodenum has been eaten away by stomach acid and digestive juices. Peptic ulcers can result from Helicobacter pylori... read more , especially in people who use aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs). Also with age, the stomach Stomach The stomach is a large, bean-shaped, hollow muscular organ consisting of four regions: Cardia Fundus Body Antrum read more cannot accommodate as much food (because of decreased elasticity), and the rate at which the stomach empties food into the small intestine decreases. However, these changes typically do not cause any noticeable symptoms. Aging has little effect on the secretion of stomach juices such as acid and pepsin, but conditions that decrease acid secretion, such as atrophic gastritis Causes , become more common. These conditions can result in subsequent problems such as vitamin B12 deficiency Vitamin B12 Deficiency Vitamin B12 deficiency can occur in vegans who do not take supplements or as a result of an absorption disorder. Anemia develops, causing paleness, weakness, fatigue, and, if severe, shortness... read more or small intestinal bacterial overgrowth Small Intestinal Bacterial Overgrowth (SIBO) Small intestinal bacterial overgrowth is a disorder in which poor movement of intestinal contents allows certain normal intestinal bacteria to grow excessively, causing diarrhea and poor absorption... read more .
Aging has only minor effects on the structure of the small intestine Small Intestine The duodenum is the first segment of the small intestine, and the stomach releases food into it. Food enters the duodenum through the pyloric sphincter in amounts that the small intestine can... read more , so movement of contents through the small intestine and absorption of most nutrients do not change much. However, lactase levels decrease, leading to intolerance of dairy products by many older adults (lactose intolerance Lactose Intolerance Lactose intolerance is the inability to digest the sugar lactose because of a lack of the digestive enzyme lactase, leading to diarrhea and abdominal cramping. Lactose intolerance is caused... read more ). Excessive growth of certain bacteria (small intestinal bacterial overgrowth Small Intestinal Bacterial Overgrowth (SIBO) Small intestinal bacterial overgrowth is a disorder in which poor movement of intestinal contents allows certain normal intestinal bacteria to grow excessively, causing diarrhea and poor absorption... read more ) becomes more common with age and can lead to pain, bloating, and weight loss. Bacterial overgrowth may also lead to decreased absorption of certain nutrients, such as vitamin B12, iron, and calcium.
Pancreas, liver, and gallbladder
With age, the pancreas Pancreas The pancreas is an organ that contains two types of glandular tissue: Pancreatic acini Islets of Langerhans (See also Overview of the Digestive System.) The acini produce digestive enzymes.... read more decreases in overall weight, and some tissue is replaced by scarring (fibrosis). However, these changes do not decrease the ability of the pancreas to produce digestive enzymes and sodium bicarbonate. As the liver Liver The wedge-shaped liver is the largest—and, in some ways, the most complex—organ in the body. It serves as the body's chemical factory, performing many vital functions, from regulating the levels... read more and gallbladder Gallbladder and Biliary Tract The gallbladder is a small, pear-shaped, muscular storage sac that holds bile and is interconnected to the liver by ducts known as the biliary tract. (See also Overview of the Liver and Gallbladder... read more age, a number of structural and microscopic changes occur (see also Effects of Aging on the Liver Effects of Aging on the Liver A number of structural and microscopic changes occur as the liver ages. (See also Overview of the Liver and Gallbladder for a discussion of normal function of the liver and gallbladder.) For... read more ).
Large intestine and rectum
The large intestine Large Intestine The large intestine consists of the Cecum and ascending (right) colon Transverse colon Descending (left) colon Sigmoid colon (which is connected to the rectum) read more does not undergo much change with age. The rectum Rectum and Anus The rectum is a chamber that begins at the end of the large intestine, immediately following the sigmoid colon, and ends at the anus ( see also Overview of the Anus and Rectum). Ordinarily,... read more does enlarge somewhat. Constipation becomes more common (see also Constipation: Essentials for Older People Essentials for Older People Constipation is difficult or infrequent bowel movements, hard stool, or a feeling that the rectum is not totally empty after a bowel movement (incomplete evacuation). (See also Constipation... read more ), which is caused by many factors:
A slight slowing in the movement of contents through the large intestine
A modest decrease in the contractions of the rectum when filled with stool
More frequent use of medications that can cause constipation
Often less exercise or physical activity
Pelvic floor weakness in older women
Pelvic floor weakness in older women can also contribute to fecal incontinence Fecal Incontinence Fecal incontinence is the loss of control over bowel movements. Fecal incontinence can occur briefly during bouts of diarrhea or when hard stool becomes lodged in the rectum ( fecal impaction)... read more .