Foods that are high in fiber or have hard shells, like sweetcorn, often pass through the body undigested. However, other undigested foods in stool could indicate an underlying condition, such as Crohn’s disease.
When undigested food in the stool occurs with a change in bowel habits, weight loss, or diarrhea, this may signal an underlying condition that needs medical attention.
In this article, we look at why undigested food may appear in stool and when a person may consult a doctor.
There are some reasons why the body might not completely digest foods that do not cause concern.
Undigested food can appear in the stool if there is material in food that is indigestible, such as cellulose in some high fiber foods. This could be due to a person not chewing the food well or the food containing shells or skins that the body’s natural enzymes cannot break down.
It could also happen if food passes too quickly through the digestive system. For example, if the person has a condition such as Crohn’s disease, which causes inflammation in the digestive system. It can also happen if someone has gastric surgery or a bowel resection.
Fiber refers to the indigestible part of plant foods. A high fiber diet can have many benefits, including keeping the digestive system healthy and keeping bowel movements regular.
When a person eats high fiber foods, it is common for some undigested material to appear in the stool because the body cannot fully break down the tough material.
Fiber also speeds up a person’s bowel movements by adding bulk to the stool, which encourages the intestinal walls to move. This movement pushes food through the digestive tract.
If food moves too quickly through the digestive system, a person may not fully digest some foods.
Certain foods are more likely than others to be difficult to digest fully. These foods include:
Foods such as corn often remain partially undigested. Corn has an outer shell made of an indigestible material called cellulose. The body digests the material inside of the corn and expels the hard outer casing into the stool.
When a person eats too fast and swallows their food without fully chewing it, it is more likely to pass through the digestive tract without completely breaking down.
Eating too quickly may result in incomplete digestion, where food does not break down completely. To avoid this, people can slow their eating during meals and chew their food for longer.
The most common cause of undigested food appearing in stool is fibrous foods. However, some medical conditions can result in whole or partially digested food appearing in stool.
This condition is a type of inflammatory bowel disease that causes inflammation in the digestive tract.
This is an autoimmune disorder where the body cannot digest the protein known as gluten, which occurs in wheat, barley, and other grains.
A person with pancreatic insufficiency lacks enzymes in the pancreas, making it hard to break down food. This could lead to undigested food appearing in stool.
If a person’s digestive system cannot break down the protein in milk and dairy, it may indicate lactose intolerance.
Irritable bowel syndrome (IBS)
IBS is a common condition that affects the large intestine.
Symptoms include:
- bloating and pain
- diarrhea, constipation, or both
- the feeling that a bowel movement is unfinished
- white mucus in the stool
Some people may also notice undigested food in their stool.