Large Intestine - 3 Ways to Build Happy Gut Bugs

Large intestine health highlights:

Large Intestine Function:

  • Extract water and minerals before elimination
  • Ferment fibers by colonic bacteria

When Things Go Wrong:

  • IBS (diarrhea, constipation)
  • Dysbiosis
  • Inflammation/IBD/Crohn’s/Ulcerative Colitis

Supporting the Large Intestine:

  • Remove inflammatory gut irritants
  • Try an elimination protocol like the Autoimmune Paleo protocol
  • Feed your gut bugs


Def. Large Intestine: 

The large intestine is a 5-foot muscular tube responsible for absorbing water, electrolytes and fermenting fibers to benefit colon wall cell health.

The large intestine connects the small intestine to the rectum. The ileocecal valve, located at the end of the small intestine, serves as a one-way valve and connects the small intestine to the large intestine. The ileocecal valve prevents bacteria and contents of the large intestine from moving back in the small intestine.

The large intestine is divided into 3 sections:

  • ascending colon (up the right side of the body)
  • traverse colon (across the body)
  • descending colon (down the left side of the body)

In a properly functioning large intestine, food resides for roughly 16 hours.


Function: Large Intestine

Water & Mineral Absorption

After completing the intensive nutrient and mineral absorption process in the small intestine, chyme enters the large intestine ready to be condensed and solidified. In a properly functioning digestive system, by the time stool reaches the large intestine, most nutrients and 90% of water has been absorbed by the body.

The large intestine extracts the remaining water and salts (electrolytes) to be used by the body before elimination.

When contents pass too quickly through the large intestine (total transit=less than 18 hours), and water is not adequately absorbed, diarrhea can occur.

When contents pass too slowly through the large intestine (total transit=more than 24-36 hours), and water is completely extracted, constipation can occur.


The majority of our gut’s bacteria is located in the large intestine. A healthy gut is comprised of approximately 100 trillion microorganisms from over 500 species of bacteria. These bacteria aid in digestion, synthesize vitamin B and K2 and produce short chain fatty acids (SCFAs) which help feed and build the colon’s cell lining.

These gut bacteria, including the strain bifidobacterium, break down fiber and resistant starches to produce SCFAs. These SCFAs (butyrate, acetate and propionate) feed the colon’s epithelial cells which contributes to the overall cell health of the large intestine.


When Things Go Wrong:

1. Irritable bowel Syndrome (IBS)

Irritable bowel syndrome is defined by the Rome III Diagnostic Criteria for Functional Gastrointestinal Disorders as recurrent abdominal pain or discomfort at least 3 days/month in the last three months. But more specifically, symptoms include:

  • Abdominal pain
  • Altered stool frequency and form
  • Gas and bloating

IBS is divided into symptomatic categories:

  • IBS-C (or C-IBS) — Constipation-dominant
  • IBS-D (or D-IBS) — Diarrhea-dominant
  • IBS-A — Alternating between the two, also sometimes seen as M-IBS (Mixed)

IBS can be a rather vague diagnosis, and it's causes and triggers are a bit all over the board, too.

Common causes include:

  • Discordant communication in the brain-gut -- 90% of serotonin receptors are in the gut (along with 95% of our serotonin), and controls the rate at which food moves through the GI tract (Bauman, 2015).
  • Stress –- food sensitivities, emotional stress, physical pain, infections, environmental toxins
  • Altered bacteria and dysbiosis, especially by bacteria in the small intestine


2. Dysbiosis

Our intestinal tract is highly active and a breeding ground for over 500 bacteria species. Feeding these bacteria with healthy prebiotics, probiotics and an anti-inflammatory diet can go a long way in creating flourishing gut bacteria.

However, environmental and medications can hamper good bacteria from thriving:

  • Antibiotics – can kill healthy bacteria, and allow harmful pathogens to proliferate
  • Non-steroidal anti-inflammatory drugs (NSAIDs) - increased use can be destructive to intestinal bacteria
  • Excessive alcohol consumption
  • A diet lacking in vegetables, fruit and starches – fiber and resistant starch feeds bacteria and produces SCFA’s – critical for colon cell health


3. Inflammation/IBD/Crohn’s/Ulcerative Colitis

Inflammatory Bowel Disease (IBD) simply put, is chronic inflammation of the gut. Crohn’s and Ulcerative Colitis are both autoimmune diseases.

Symptoms of both include:

  • Frequent or spontaneous stomach pain
  • Intestinal cramping
  • Nausea
  • Fatigue
  • Diarrhea
  • Constipation
  • Blood in the stool


Supporting the Large Intestine

  1. Remove inflammatory gut irritants -- grains, gluten, sugar, beans, dairy, food allergens and toxins -- can all promote inflammation in the digestive tract. Follow a Paleo or 4-R protocol to remove irritants to heal and repair the digestive tract.
  2. Try an elimination protocol like Autoimmune Paleo, especially if suffering from an autoimmune IBD like Crohn’s or Ulcerative Colitis. While this approach can be intense, it’s a fantastic method to determine if your body reacts to seemingly “good-for-you” foods like nightshades and eggs.
  3. Feed your gut bugs

Probiotics contain live and healthy bacteria. Food sources include full-fat, organic dairy, sauerkraut, pickles, kombucha, vinegar and kimchi.

Prebiotics act as food for our gut’s good bacteria, bifidobacteria and lactobacillibacteria. Resistant starch and the soluble fiber inulin and fructooligosaccharides (FOS) feed the good gut bugs. Food examples of inulin and FOS include chicory root, Jerusalem artichokes, garlic, onions and dandelion greens.

The large intestine is full of trillions, yes trillions of bacteria! These bacteria synthesize vitamins, produce short chain fatty acids and support digestion.

One of the best ways to support the large intestine is to not overburden it with food allergens and eat both pre- and probiotics!