Why Does Your Stomach Growl?

Why does the stomach "growl" or make noises?

Everyone's stomach growls, some growl more than others. The growls, technically called borborygmi (pronounced BOR-boh-RIG-mee), are caused primarily by contractions of the muscles of the stomach and small intestine and, to a lesser extent, by contractions of the muscles of the large intestine (colon).

The stomach and intestines are hollow organs consisting primarily of muscle. The muscles are important for digesting food. Different actions of the muscles can cause the food to be ground, mixed, stored, and transported along the length of the intestine and expelled. As part of the process of digestion, fluid is secreted into the stomach and intestines. Gas also appears in the stomach and intestines either as a result of swallowing air or production of gasses by intestinal bacteria. Thus the stomach and intestines contain a mixture of digesting food, liquid, and gas.

As the muscles of the stomach and intestines contract and squeeze their contents, the contents move. It is the movement of the food, liquid, and particularly the gas that gives rise to borborygmi. Because food, liquid, and gas are most commonly present in the intestines after a meal, this is the time when we most frequently are aware of borborygmi. We also may be more aware of them at night while lying in bed because-at least if the TV is not turned on--it is quiet.

Borborygmi may be prominent in a few abnormal conditions. Thus, they may occur when there is physical obstruction of the intestine that blocks the transport of the digesting food, for example, by a tumor. Because of the blockage, muscle behind the blockage contracts more strongly and frequently trying to overcome the blockage. This can give rise to louder borborygmi. Unlike normal borborygmi, however, the borborygmi associated with obstruction usually are associated with crampy abdominal pain. If the obstruction is not relieved, the muscle eventually gets tired and stops contracting. The cramps stop, gas and fluid continue to collect behind the obstruction, and the abdomen swells.

Another situation in which borborygmi may be prominent is a condition called bacterial overgrowth of the small intestine. In this condition, gas-producing bacteria increase in numbers in the small intestine and produce abnormally large amounts of gas. The increased amount of gas (and possibly stronger contractions of the intestinal muscles caused by additional distention of the intestine by gas) gives rise to louder borborygmi. Bacterial overgrowth often-but not always--gives rise to an increased amount of flatulence (farting) and even abdominal bloating or distention.

Sometimes there is no explanation for prominent borborygmi. I remember a friend who called me about his teenage daughter who was having a difficult time with her first period study hall in high school. It seemed that she was having embarrassingly-loud borborygmi made even worse by the fact that the school room was quiet. The daughter was healthy and without other gastrointestinal symptoms. Fortunately, we were able to solve the problem by giving her a teaspoon of olive oil with her breakfast. (Fatty acids that are released from the digestion of fat and oils in the intestine are potent blockers of intestinal contractions. The olive oil reduced her borborygmi by reducing the strength of her intestinal contractions.)