As we continue our trip through the parts of the GI tract, the next stop for food is the small intestine. Remember the first stops on this journey were the mouth and esophagus first, followed by the stomach. The stomach passes food through the pyloric sphincter into the small intestine. This process can take a while: meals take anywhere from 2 to 6 hours to fully empty into the small intestine. The pyloric sphincter opens every few minutes and allows about a tablespoon or so of digested food (or chyme) into the small intestine at a time.
Digestion
What happens in the small intestine is interesting, but also a little gross! The first part of the small intestine is the duodenum. Here, digested food mixes with enzymes that come from the pancreas and the gall bladder. Whereas the stomach mostly digests protein, the enzymes in the duodenum break down protein, carbohydrates and fat to make them easier to absorb. The duodenum also secretes fluids that help make the chyme from the stomach less acidic.
Absorption
The small intestine has lots of folds and tiny finger-like structures called villi. The large surface area of the small intestine means there’s plenty of room to absorb nutrients. In fact if you could flatten the small intestine, it would be about the size of a tennis court! The small intestine is actually the part of the GI tract where most nutrients are absorbed. Some nutrients are absorbed near the front of the small intestines, in the duodenum. But most of the absorption in the small intestine happens in the second two parts, the jejunum and the ileum. Each section of the small intestine is a little different, and absorbs different nutrients.
Disorders of the Small Intestine
Because it’s so good at absorption, patients who are missing part of their small intestine can have trouble getting all of the nutrients they need. A good example is patients with short bowel syndrome(SBS). Those patients may need a formula like Neocate that requires less digestion and which is easier to absorb, with high levels of nutrients. The high nutrient levels and unique fats in Neocate also make it a good choice for patients with other disorders that affect digestion and absorption, such as protein maldigestion or fat malabsorption. Some patients might also have a condition called Food Protein-Induced Enterocolitis Syndrome(FPIES). This is related to Eosinophilic Esophagitis(EoE), and Neocate can also help.
Stay tuned for next week’s article in the Gut Series, which will discuss the large intestine!
– Rob
