While the act of swallowing is conscious, once food passes into the stomach, it moves along through the rest of the gastrointestinal tract based upon the rate of peristalsis, or waves of muscular motion through the stomach and intestine. Since peristalsis is not under conscious control, it’s not possible to control the rate of digestion or the rate at which food progresses from the stomach to the anus. There are several peristalsis-related factors that can contribute to slow digestive function.
Pregnancy
In their book, “What To Expect When You’re Expecting,” Heidi Murkoff and Sharon Mazel note that one of the classic symptoms of pregnancy is constipation. As a result of pregnancy hormones, the muscles of the digestive tract relax somewhat. This is useful, since slower-moving digestive tracts are more efficient at extracting every bit of nutrition from consumed food, which ensures that there are plenty of calories and nutrients for a growing baby, but the downside of a slow digestive tract is that it allows native gut bacteria more time to digest bits of meals that humans can’t digest, leading to gas and bloating. While there’s really no way to speed up a pregnant woman’s slow digestive tract, maintaining a good diet may help keep stools relatively regular.
Low Fiber
Since the digestive system is mechanical, it relies upon food bulk in order to be able to move food efficiently. Imagine trying to squeeze toothpaste out of a tube—it’s much easier to squeeze the paste out when there’s a lot of it as opposed to a very small amount. In the same way, low-bulk meals are difficult for the intestine to get hold of and move along the tract, which tends to slow the rate at which they progress through. Higher-bulk meals, generally meaning meals that include plenty of fiber, which provides indigestible bulk material, take up more room in the intestine and are easily sped along by peristaltic waves, notes Dr. Gary Thibodeau in his book, “Anatomy and Physiology.” This is one of the reasons that high-fiber diets are associated with regularity and good nutrition—in addition to preventing constipation, high-fiber diets reduce the amount of time that fecal matter sits in the intestines, which limits the potential for toxin absorption.
Dehydration
A final factor that helps maximize the function of the human digestive tract is ample mucus, which helps lubricate the lining of the intestine and makes it easier for food to slip by. Appropriate hydration, notes Dr. Lauralee Sherwood in “Human Physiology,” ensures that mucus production occurs at a normal rate. This in turn promotes an efficient digestive tract, reduces the amount of time food spends in the intestine, decreases intestinal gas formation, and improves regularity of bowel movements.
References
- “What to Expect When You’re Expecting”; Heidi Murkoff and Sharon Mazel; 2008
- “Anatomy and Physiology”; Gary Thibodeau, Ph.D.; 2007
- “Human Physiology”; Lauralee Sherwood, Ph.D.; 2004
