Content Reviewers:Rishi Desai, MD, MPH
In short bowel syndrome, bowel is another word for the intestines.
It’s a condition that occurs when either the small intestine and/or the large intestine become physically shorter when a portion is removed by surgery, or functionally shorter, when a portion is damaged in a way that makes it nonfunctional.
This can lead to poor absorption of water and vital nutrients from food.
Normally, digestion begins when food is chewed and travels into the stomach where it’s dissolved by stomach acid, enzymes, and physical churning.
Then, it’s sent to the first portion of the small intestine, which is called the duodenum.
It’s also where the absorption of some minerals like calcium, iron, and magnesium begins.
The next section is called the jejunum, and it has long projections on its surface, giving it a large surface area for absorption.
It plays the biggest role in the digestion and absorption of most nutrients, including the breakdown-products of macronutrients, zinc, water-soluble vitamins, and fat soluble vitamins, namely A, D, E, and K.
The third section is called the ileum, and it has tight intercellular junctions, allowing it to efficiently absorb fluid and begin concentrating the intestinal contents.
Unlike the jejunum, the ileum is also capable of undergoing structural and functional adaptations to compensate for the jejunum if needed.
The final portion is called the terminal ileum, and it absorbs vitamin B12 and bile salts which are recycled.
It ends with the ileocecal valve, which prevents intestinal contents from going into the large intestine too quickly and the backward flow of material.
Since each part of the small intestine has a specialized function, as does the large intestine, the manifestations of short bowel syndrome depend on which portion is no longer functioning normally.