SBS and Gut Adaptation


Posted 3.22.11 | Mallory West

We’ve talked about Short Bowel Syndrome (SBS) in previous posts. Our last post on SBS talked about how the small intestine is the absorption hub on the GI tract. When part of the small intestine is removed, you lose that important area for water and nutrient absorption and your body is no longer able to utilize the food and liquid that you consume. For this reason, total parental nutrition (TPN) may be necessary at first. Remember that TPN is nutrition that is delivered straight into the blood stream, rather than going through the digestive tract. The digestion and absorption processes are skipped.

Although this can sustain someone, there are many risks associated with TPN and in order for the remaining portion of the small intestine to adapt, it is very important to start enteral nutrition (EN) as soon as possible. Recall that EN is where nutrition is delivered through the digestive tract, either through a feeding tube or by eating regularly. So what exactly does it mean for the small intestine to adapt? We’ll focus on this subject in today’s blog post!

What is intestinal adaptation?

After a significant portion of the small intestine is removed, the remaining small intestine goes through a process of adaptation that increases its ability to absorb water and nutrients. What changes are involved in adaptation?

  • The remaining portion of the small intestine may grow slightly in length
  • The remaining portion of the small intestine may grow in diameter (width)
  • The inner lining of the small intestine grows, increasing in surface area and the ability to absorb

The growth of the inner lining and absorptive capacity is perhaps the most important feature. How does the growth of the inner lining improve the ability to absorb nutrients? Think about a sponge, which we use to absorb liquid. The reason that it absorbs so well is the nooks and crannies which give the sponge a large surface area. Think about a 2 by 2 inch sponge in comparison to a 2 by 2 inch wood block. The sponge will absorb much more due to the high surface area. The growth of the inner lining of the intestine increases the surface area to form nooks and crannies so that it can absorb efficiently, like a sponge.

The prognosis of a patient with SBS depends on how well their gut adapts. If the remaining portion adapts enough, it will be able to compensate for the lost portion of the intestine. Once this happens, TPN can be stopped because the digestive tract is now able to absorb enough nutrients and water from the diet.

Can you support the adaptation process or speed it up?

Intestinal adaptation can take up to 2 years to occur. The best way to support gut adaptation is to eat! Consuming some foods by mouth or through a feeding tube triggers the release of certain hormones and promotes blood flow to the GI tract. The hormones and blood flow promote the adaptation process. This is why it’s so important to start enteral nutrition as soon as possible. TPN continues to deliver the bulk of nutrients that the patient needs to live and be healthy, so the food in the digestive tract is not expected to fulfill this role yet. But little by little, the patient is able to tolerate more foods through the GI tract and able to absorb more and more nutrients until eventually, their gut has adapted enough to allow them to stop the TPN. Check out our previous post on how Neocate can help children with SBS wean off of TPN sooner.

Researchers are studying ways to help the gut adapt quicker and function better. You can check out some of the research being done on SBS online at clinicaltrials.gov.

To view a true story about a little girl with SBS who is in the adaptation process, check out this video, Elizabeth's story,fromJohns Hopkin's Children's Center.

I hope this post helps you to better understand SBS and how gut adaptation works. If you have any personal experiences, please share them with us!

-Mallory

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Food Allergy Living is a resource for parents of children with food allergies, brought to you by Nutricia, the makers of Neocate. For more in-depth information about our purpose & authors, see our About Food Allergy Living page.