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What Are Gut Flora?

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Updated November 05, 2012

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Question: What Are Gut Flora?

I've heard all about colon cleansing, good bacteria, and bad bacteria, but what are gut flora? Aren't all germs bad for you?

Answer:

Those are good questions. Gut flora is the slang term given to both good and bad bacteria that live inside your digestive tract. The type and amount of bacteria present depends on their location in your body (small intestine versus colon). As the storage house for stool, your colon is filled with hundreds of different types of bacteria, which have specific jobs to do.

Bad Flora

You've probably heard about some of the more common pathogens, which are bacteria that can cause illness in humans if left unchecked, including germs like streptococcus (strep throat) or E. coli (urinary tract infections and diarrhea). Some of the other common germs found in the human colon include:

  • Clostridium difficile (C. diff) overgrowth can cause you to have multiple green, foul smelling and watery stools daily, as well as abdominal pain and tenderness.
  • Enterococcus faecalis is one of the causes of post-surgical infections in the abdomen and urinary tract infections.
  • Escherichia coli (E. coli) is the most popular cause of diarrhea in adults, and this bacteria is present in almost every healthy adult’s colon.
  • Klebsiella overgrowth is associated with a Western diet including many meat and animal products.
  • Bacteroider overgrowth is associated with colitis, or a painful inflammation of the colon.

Good Flora

The good bacteria, such as Bifidobacteria and Lactobacillus, help keep these bad bacteria in check. Without the good flora, your entire colon would become over run by bad flora, which would result in symptoms like diarrhea or even illness. These protective, microscopic germs have many important functions including:

  • Destroying bad bacteria and preventing overgrowth
  • Breaking up gas bubbles from food fermentation
  • Boosting your immune system's function
  • Assist with vitamin synthesis (vitamins B and K in the small intestine)
  • Keep your bowel movements regular
  • Keep your colon "clean" (naturally) negating the need for colon cleansers

Destroying the Good with the Bad

Whether labeled as a "good" bacteria or a "bad" one, they are both single-celled organisms that are destroyed fairly easily. Sometimes, it's a necessary evil, such as when you have to take antibiotics to kill a strep throat infection. However, the antibiotics also kill your good bacteria, which can lead to compounding problems such as:

  • Bowel irregularity (diarrhea and constipation)
  • Yeast overgrowth (can cause itching, burning around your anus and lead to vaginal and oral yeast infections)
  • Dysbiosis (the technical name for a lack of good bacteria or a bacterial imbalance)
  • Complications for people suffering Irritable Bowel Syndrome or Disease

There are many ways to destroy bacteria, some of which are out of your control. If you need to take antibiotics to cure an infection, you may kill off your bacteria, good and bad. Similarly, bacteria can be destroyed by:

  • Chronic laxative or fiber supplementation
  • Prolonged diarrhea (flushes out the bacteria)
  • Stress (emotional)
  • Completing a bowel prep, like the one required for a colonoscopy

Diagnosing Problems with Gut Flora

Often times, problems with gut flora will correct themselves, and no action is required on your part. However, people facing chronic bowel problems, such as colitis or Irritable Bowel Disease, may need more aggressive management of their colon's bacteria. The Comprehensive Digestive Stool Analysis (CDSA), is a stool test that checks what type and amount of bacteria are present, your nutrient absorption rates (how fast you digest) and how well you digest your food. If there is a significant difference in your proportion of bad versus good bacteria, your doctor might suggest taking a probiotic, or a live microbial supplement that can help repopulate the good flora in your colon.

Probiotics and Prebiotics

Although they are sometimes used interchangeably, a probiotic is not the same thing as a prebiotic. Probiotics are the actual bacteria, whereas prebiotics are non-digestible foods that help establish a healthy environment for good bacteria to thrive. Different types of dietary fiber, such as inulin, are prebiotics. Well known probiotic foods include yogurt and other fermented foods, such as sauerkraut.

Sources:

Galland, L. & Barrie, S. (n.d.). Intestinal Dysbiosis and the Causes of Disease. The Environmental Illness Resource. Accessed October 19, 2012.

Hawrelak, J.A. & Myers, S.P. (2004). The Causes of Intestinal Dysbiosis: A Review. Alternative Medical Review; 180-197. Accessed at PubMed.gov on October 19, 2012.

Medline Plus. (n.d.). Clostridium Difficile Infections. Accessed October 19, 2012.

Todar, K. (n.d.). The Normal Bacterial Flora of Humans. Todar's Online Textbook of Bacteriology. Accessed October 19, 2012.

University of Maryland. (n.d.). Pathogen Descriptions: Enterococcus. Accessed October 19, 2012.

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