Fast Facts About Gut Microflora

Filed Under: Digestive Health, Gut Bacteria & Probiotics
Last Reviewed 09/09/2015

image of human digestive tract

For the health trivia buffs out there, the microflora in the gut—and the human microbiome in general—offer thousands of factoids to learn and file away. I'm not sure I'd be too gung-ho about sharing them, though, unless you're discussing their benefits over a cold, naturally fermented beer. In that case, there's no better way to justify a second round.

Here are just a handful:

  • More than 1,400 different bacteria species have been identified in the intestines.
  • The bacteria living in your gut make up about 2 pounds of your body weight.
  • In the stomach, very few bacteria are able to survive because of the acidity. In fact, there may be as few as 10 to 100 organisms in every milliliter (.0338 fluid ounces) of stomach content.
  • In the small intestine, there might be anywhere from 100 to 1,000 organisms per milliliter.
  • As you reach the junction between the small and large intestine (at the ileocecal valve), the numbers begin to grow. In the large intestine or colon, as many as 1 trillion organisms per milliliter are common.
  • Because our gut microflora change with age, people over 50 tend to have lower levels of Bifidobacterium, an important microbe found predominantly in the large intestine.
  • It can take your gut flora up to a year to fully repopulate itself after just one course of antibiotics.
  • Generally speaking, we are literally covered in bacteria. For every one human cell in the body, there are 10 microbes.

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DISCLAIMER: The content of is offered on an informational basis only, and is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified health provider before making any adjustment to a medication or treatment you are currently using, and/or starting any new medication or treatment. All recommendations are "generally informational" and not specifically applicable to any individual's medical problems, concerns and/or needs.

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