Enteral nutrition, or tube feeding, delivers specialized liquid nourishment through a flexible tube directly into the gastrointestinal (GI) tract. This method bypasses chewing and swallowing, but the digestive system remains fully operational. Since the formula is delivered directly to the stomach or small intestine, the body continues the normal process of breaking down nutrients, absorbing what it needs, and eliminating waste. Therefore, a person on a feeding tube still has bowel movements, as the digestive system continues to function and process the liquid diet.
How Digestion Continues During Tube Feeding
Enteral formulas are carefully balanced liquid mixtures containing carbohydrates, proteins, fats, vitamins, and minerals that are recognized and processed by the gut. Once the formula enters the stomach or small intestine, involuntary muscular contractions of the GI tract, known as peristalsis, move the mixture through the intestines. The small intestine absorbs the majority of the nutrients and fluid from the specialized formula. Unabsorbed components, metabolic byproducts, shed intestinal cells, and bacteria continue their journey toward the colon, constituting the bulk of the waste product. The colon’s primary role of absorbing water and forming stool from the remaining residue is largely unchanged, though the characteristics of the stool will differ from a regular diet.
Expected Changes in Stool Consistency and Frequency
A primary change expected with tube feeding is a shift in the physical characteristics of the stool compared to eating solid food. Since the diet consists entirely of liquid formula, the resulting stool is often softer and can sometimes be liquid-like in consistency. This is a reflection of the high fluid content and the pre-digested, easy-to-absorb nature of many commercial formulas, and is not always diarrhea.
Frequency may also be altered, and many individuals experience fewer bowel movements. Tube feeding formulas are designed to be highly digestible, meaning the body uses a greater percentage of the formula, resulting in less undigested residue to be eliminated. Less bulk passing through the colon can lead to a decrease in the frequency of defecation, which is a normal occurrence.
Changes in stool color and odor are also common and are often related to the specific ingredients within the formula. Formulas rich in certain vitamins, iron, or specific protein components can subtly alter the color of the stool, sometimes making it lighter or giving it a greenish hue. The high digestibility and liquid nature of the diet can also result in a different, sometimes more pronounced, odor than stools formed from a traditional diet.
Managing Common Gastrointestinal Issues
The rapid introduction of liquid formula can sometimes lead to common gastrointestinal disturbances. Diarrhea, defined as frequent, loose, or watery stools, is a common issue that can be caused by the rate of feeding being too fast, contamination of the formula, or certain medications given through the tube. For example, liquid medications containing sorbitol are known to increase intestinal motility and contribute to loose stools.
Conversely, constipation is also frequently encountered, often characterized by infrequent, hard-to-pass stools. This often results from inadequate fluid intake, a lack of fiber in the formula, or reduced physical activity. Certain medications, such as pain relievers, can also slow the movement of the gut, contributing to constipation.
Simple interventions are often employed to manage these issues. For diarrhea, slowing the rate of the continuous feeding or temporarily changing to a clear liquid diet may help the gut adjust. Ensuring adequate “free water” flushes through the tube is a strategy used to prevent dehydration and manage both diarrhea and constipation. If constipation is the problem, a healthcare provider may recommend switching to a fiber-containing formula, increasing water flushes, or prescribing a gentle stool softener or laxative.