Gut Flora

March 1st, 2013 by Eduardo Krajewski, MD, FACS, FASCRS

Did you know that there are trillions of microorganisms living inside your intestines? Actually there are 100 trillion bacteria and other organisms living inside your large intestine. Think about it. The human body is made up on only 10 trillion cells. Some have even called this collection of microorganisms the “forgotten organ,” but most scientists refer to them as the gut flora.

What are they there for?

These 500-plus species of bacteria, fungi and protozoa provide very important functions for the human body. In general, the main areas of gut flora activity are:

  • Fermenting or processing undigested material to be used as nutrition
  • Training the immune system
  • Preventing harmful bacteria from growing in the intestine
  • Cancer and allergy prevention
  • Regulating intestinal development
  • Producing vitamins and hormones

How do they get in there?

On the day we are born our intestines are sterile. But this does not last for long. Quickly we are exposed to all kinds of bacteria in our environment. These organisms eventually make their way into our intestinal tract where they grow and live for the rest of our lives.

Digestion helpers

The gut flora helps to digest some plant materials that our own digestive enzymes cannot handle. This releases many useful nutrients such as carbohydrates for our bodies to use. This also helps with the absorption of some minerals such as calcium, magnesium and iron.

Immunity stimulators

These bacterial houseguests do us another big favor. They stimulate our lymphoid glands to make antibodies to harmful intruders thus beefing up our immune system. This is a kind of immune system training program. The gut flora prepares us in advance before we get infected. So when an infectious agent appears, the body can recognize and eradicate it more easily.

Allergy prevention

This action is closely related to immune stimulation. Our body reacts in one way or another to any perceived threat. Sometimes these reactions are not precise. Allergies are an exaggerated response of our immune system. So your runny nose is just your body overreacting to a potential environmental threat by coating your nasal passages with a protective fluid. The gut flora, it is believed, exposes the body in small amounts to pathogens. This low level exposure trains the body to respond appropriately.

Cancer prevention

The gut flora may also help us avoid cancer. There is some scientific evidence that suggests that the gut flora helps process carcinogens that are naturally found in foods. These harmful elements are metabolized by the bacteria and, therefore, rendered harmless.


Antibiotics kill bacteria. And they often don’t discriminate, especially the “wide spectrum” antibiotics. For this reason, one of the side effects of antibiotic use is the disruption of the gut flora. Sometimes only one organism is allowed to take over in overwhelming numbers, and this can lead to very severe diarrhea.


The gut flora can be influenced by our diet, and there is an exciting field of research surrounding this phenomenon. Scientists are looking into how specialized bacteria, or probiotics, can be used as a diet supplement. There is some promise that this might lead to new ways of treating inflammatory bowel disease, infections, arthritis and even cancer.


The gut flora is a fascinating aspect of human biology. You are carrying around a hundred trillion tiny passengers in your gut. But these little buggers aren’t free-loaders; they do a great service to you and your health.

Check out The H Doctor website. You will find many other articles and videos that give useful information about hemorrhoid treatment and other important digestive health topics.

Have an outstanding day!


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