Intestines

In general, aging does not affect the transport of food through the intestines. Our intestines do not change significantly in their ability to absorb foods as well as drugs, although there are a few exceptions. For example, changes in the metabolism and absorption of lactose, calcium and iron can occur. As we age the small intestines absorb less calcium. Therefore, we need more calcium to prevent bone mineral loss and osteoporosis in later life. Some enzymes, such as lactase which aids the digestion of lactose (a sugar found in diary products) decline with age.

The prevalence of diverticulosis increases with age. Almost all of us, if we live long enough, will have diverticula-- small outpouches in the colon. This condition is caused by increased pressure in the colon as a result of impaired intestinal muscle function and weakness in the intestinal wall. Diverticula can be uncomplicated or they can become inflamed (called diverticulitis) and result in great pain. Diverticulitis can be prevented by maintaining a high intake of fiber.

Studies of motility in older adults show reduced peristalsis (intestinal muscle contractions) of the large intestine (colon). This slower rate of food transport can contribute to constipation. However, constipation is aggravated by a low intake of fiber and water, inactivity, medications, and overuse of laxatives.