Keep Your Digestive System in Shape - Focus on Fitness - Harvard Commentaries

Last reviewed on January 27, 2012

By Paulette Chandler, M.D., M.P.H.
Brigham and Women's Hospital

In recent years many products have been touted for rejuvenating the intestinal tract and enhancing digestive health through "colon detoxification and cleansing." But despite the glowing claims, almost all these products have no scientific proof of effectiveness. The real keys to a healthier digestive system are diet and regular exercise. Refined, processed, low-fiber foods, animal fats, chronic stress and a lack of physical activity are the foundation for a host of gastrointestinal diseases, including colorectal cancer, heartburn, diverticulitis and constipation. Proper digestion, absorption of nutrients and elimination of waste products are aided by a good exercise program and healthy diet.

Digestive problems can occur at any weight, but bloating, heartburn, and constipation are more common in people who are overweight. Extra pounds increase pressure within your abdomen and force stomach acid (reflux) into your esophagus. This reflux of acid produces heartburn — a burning sensation in your esophagus. Excess weight also can predispose you to gallbladder disease and, possibly, colon cancer.

The Exercise Tonic

Exercise is a great tonic for the mind, body and stomach. Exercise helps to control weight and prevent constipation. Aerobic exercise (exercise that increases your breathing and heart rate) and deep breathing exercises are very beneficial for healthy digestion, because they stimulate the natural contraction of intestinal muscles, helping to move food through your intestines more rhythmically.

Avoid heavy exercise after a large meal. Digestion requires a large amount of blood flow to your stomach and intestines. If you exercise immediately after eating, digestion will be put on hold while blood is redirected to support the increased work of the heart and muscles. With the reduction in blood supply to the gut, the gut muscles contract less vigorously, digestive enzymes are secreted in smaller amounts, and the transit of food waste shifts into slow motion. This can lead to heartburn, bloating and constipation.

Stress can cause a similar shift in blood flow away from the gut, as muscles tense and heart rate accelerates, demanding more oxygen delivery to the active muscles. Daily exercise is a well-known stress buster through a variety of mechanisms, including boosting the release of endorphins — the "happy" hormones. The same neurotransmitters and receptors that dictate mood in the brain exist in great abundance in the gut and influence digestion.

Other Strategies for Good Digestive Health

Eat plenty of fiber-rich foods. Plant foods are excellent sources of fiber as well as other beneficial vitamins and minerals, such as selenium, calcium and folate that may protect against digestive-tract cancers. Dietary guidelines recommend 25 to 35 grams of fiber a day. Fiber promotes softening and bulking of stool to prevent constipation and reduce symptoms of disorders such as irritable bowel syndrome and hemorrhoids. Increase the amount of dietary fiber gradually over a period of weeks to avoid excess intestinal gas and abdominal bloating.
Reduce fat. Excess fat slows digestion and can lead to heartburn, bloating and constipation.
Avoid cold drinks while eating. Food is digested more efficiently at room temperature. Cold fluids slow down the digestive process.
Drink plenty of fluids in between meals. Fluids promote healthy digestion by lubricating food waste so that it passes more easily through your digestive tract.
Don’t rush eating. Digestion begins in the mouth. Chew food until it is near liquid consistency. Chewing food generates saliva with enzymes that begin the breakdown of food. Chewing also signals the organs such as the stomach and pancreas to secrete their digestive juices. These digestive enzymes flow more freely in a calm environment. Also, air swallowed during hurried eating can produce belching or bloating.
Eat meals at regular intervals and avoid overeating. The body produces a certain volume of digestive juices. Thus, large meals are poorly digested and stress the system. With a regular schedule, your digestive organs have time to rest between meals.
Try a short walk after a meal. It is a great stimulus for digestion.
Limit alcohol. Alcohol can irritate the stomach lining and relax your lower esophageal sphincter, the valve that prevents stomach acid from backing up into your esophagus.
Avoid tobacco. Tobacco has harmful effects on all parts of the digestive system.

The same good behaviors that prevent heart disease and stroke — daily doses of exercise, regular checkups, a daily multivitamin, healthy diet and no smoking — boost digestive fitness.

Paulette Chandler, M.D., M.P.H. is a clinical instructor of medicine at Harvard Medical School and an attending physician at Brigham and Women's Hospital.