10 Surprising Colon Facts

Doctor with 3D model of the colon.

Last Updated: October 3, 2023

Your colon is an integral part of the digestive system, also known as your gastrointestinal tract (GI).

Most of the digestion process is already done by the time food makes its way to the colon. After food passes through the small intestine, the colon’s main function is to absorb water, vitamins and electrolytes from the semi-digested food. Your colon then begins the process of eliminating the waste through the stool (feces).

Understanding the workings of your colon can help better enable you identify common colon conditions, and make it easier for you to talk about this important organ with your doctor.

Here are 10 colon facts to help you become better acquainted with your large intestine, including the function and location of your colon, how long your intestines are, and more.

It Takes Food 12-24 Hours to Exit the Colon

It is commonly believed by some people that food is released as waste in the next bowel movement after eating. However, it can actually take a while for food to complete the full length of the digestive tract.

The amount of time it takes is called transit time, which can vary from individual to individual. Some factors that influence transit time are:

  • Diet
  • How physically active you are
  • Gender
  • Race

Generally, a transit time of more than 72 hours could be an indication of a bowel problem.

Your Colon Is Home To Trillions Of Bacteria

The large intestine contains approximately 100 trillion microorganisms. Referred to as microbiota, or gut flora, they are comprised mostly of bacteria.

Because of the importance of of microbiota to digestive health and immune function, the use of probiotic supplements and foods are a popular way to help maintain good gut health.

The Colon Measures 5 Feet Long

Your large intestine extends from the end of the small intestine’s end to to the anus. The colon is approximately 5 feet long and is in the shape of an upside-down U that goes up one side of the abdomen, across the top, and down the other side.

It’s 3 inches wide at the cecum, which is its widest point. At its narrowest point (the sigmoid colon) it’s a little less than 1 inch wide.

The following are the different parts of your large intestine, in order:

  • Cecum
  • Ascending colon
  • Transverse colon
  • Descending colon
  • Sigmoid colon
  • Rectum
  • Anal canal

How Often You Have Bowel Movements Varies

It’s a popularly thought that having one bowel movement per day is the norm, but studies do not currently support this. How often bowel movements occur can vary greatly from person to person, and even varies for any one person.

The Colon Is Never Completely Empty

Just because you had repeated trips to the bathroom from diarrhea, or haven’t eaten in a while, doesn’t mean that your colon is completely empty. Because fecal matter consists largely of bacteria, it is constantly being made.

You Can Survive Without a Colon

Most nutrients in food are absorbed by the small intestine.

Certain health conditions (such as colon cancer and inflammatory bowel disease) may require the removal of a person’s colon. In certain circumstances, a procedure known as a colostomy is performed where an opening in the abdomen is made and a colostomy bag is used to collect feces outside the body.

Another procedure that is sometimes necessary is called a J-Pouch, or ileal pouch anal-anastomosis (IPAA). This surgery involves removing the colon and rectum and using the last part of the small intestine (the ileum) to create an internal pouch, which is typically J-shaped.

Eating Can Stimulate Bowel Movements

A process known as the gastrocolic reflex is triggered when you eat, and stimulates movement to begin along the entire digestive tract. Fatty meals or larger meals seem to lead to a greater gastrocolic response, prompting a bowel movement.

Knowing this, if you experience frequent diarrhea you might want to eat smaller, low-fat meals. On the other hand, if you are prone to constipation, eating a large breakfast with fatty foods could help to promote bowel movements.

What Is Poop Made Of?

Fecal matter is made up of a number of constituents, including:

  • Bacteria
  • Undigested food
  • Dietary fiber
  • Liquids
  • Fats
  • Proteins
  • Minerals

Stool Color Can Vary

You don’t need to be alarmed if your stool color isn’t consistent. There are many factors that can influence stool color. While healthy stools tend to be in the brown category, they can also appear yellow or orange.

Let your healthcare provider know if your stool appears bright or dark bright red, or black. This could indicate internal bleeding.

Water Determines Stool Consistency

The colon is responsible for finishing the digestive process of digestion by absorbing water and electrolytes from food leaving the small intestine. In the colon, this material is made into a stool that is passed during a bowel movement.

If you have diarrhea, the stool hasn’t been in your colon long enough to adequately absorb enough liquid to make the stool firm.

When a person experiences constipation, the opposite happens. Because the stool has been in the large intestine for too long, it becomes too hard and dried out, making it difficult to pass.

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