Large Intestine Function in Human Digestive System

The Large Intestine Function—an Overview:

The large intestine function is not just the storage of digestive waste; it does a lot more. The large intestine—also the large bowel or the colon—consists of the last part of the human alimentary canal. Both the small and the large intestines perform some important functions.

Large Intestine Function

For example, they absorb nutrients from the food. More specifically, the large intestine function is to absorb water and vitamins from the food matter. It converts the remainder into stool and expels it from the body through the anus.

The large bowel is five feet long with a diameter of 2.5 inches. The colon is much shorter in length in comparison with the small intestine. However, it has a wider diameter. It is for this reason that you call this section of the gastrointestinal tract as the "large" intestine.

There is further division of the colon into the following components. Each of these components performs a specific task related to the large intestine function.


Cecum is a small pouch which connects the small intestine to the colon. Food material, water and salts pass down from the small intestine to the colon through this pouch.


The medical scientists are of the view that appendix is a useless remnant from the evolutionary past of humans. This vestigial organ is thought to have been an important source of antibody production.

However, some experts believe that appendix is still functional. They think that it does the job of storing friendly bacterial species. Such bacteria help in the rebooting the human digestive system after diarrhea.


It is the main part of the large intestine through. It is the part where the absorption of water, salts and vitamins takes place. Stool forms in the colon which then makes its way out of the body through the process of defecation.


The last component of the large intestine is the rectum. It makes a connection with the anus. The rectum serves as a temporary storehouse for the stool. It also helps in the process of expelling the waste materials out of the body.

Large Intestine Function:

The large intestine performs various jobs. Every large intestine function is immensely important for the proper functioning of the body. Read below the detail about some of the major tasks of colon.

Absorption of Water and Formation of Stool

A very important large intestine function is the conversion of the remainder of the food material into stool. This job involves the absorption of water which takes place in the colon. Food enters into the colon from the small intestine in the form of chyme.

At this point, the chyme consists of a large amount of fluid. The absorption of this fluid is important in order to solidify the material and form the feces.

The colon consists of four regions. Food material passes onwards through muscular movements of the wall of the colon. These movements are the peristaltic movements. The food matter passes on from one region of the colon to the next.

As a result, there is absorption of water and the material gradually solidifies. It is important that the food remains in this part of the intestine for sufficient amount of time. In case, it does not stay long enough, the feces will be watery. And it is a symptom of diarrhea.

On the other hand, if the material passes through the colon too slowly, there will be too much absorption of water. In turn, it will lead to the formation of hard stool which is difficult to pass through the anus. It is a condition you call constipation.

Apart from the formation of feces, another useful large intestine function is to supply the body with water. The water absorbed from the chyme is very important for various metabolic reactions taking place in the body.

Production and Absorption of Vitamins

The production and absorption of vitamins is a significant function of large intestine. A number of bacteria reside in the colon. They help in the breakdown of food matter that is not digestible. Several useful substances form as a result of this process of breakdown.

These useful substances are vitamins, such as vitamin K. The vitamin K is immensely important for the process of blood clotting. There are various other useful substances that the bacteria produce in the large intestine. They include Biotin, and Vitamin B1, B2, B6 and B12.

The vitamins from the large intestine absorb into the blood stream through the colon. The bacteria also produce ions which dissolve in the water present in the chyme. Therefore, through the absorption of water, important ions also go into the blood stream.

On the other hand, there is the production of some byproducts, such as carbon dioxide and methane. The production of these gases is what leads to flatulence.

Balancing the pH

The process of fermentation that the intestinal bacteria perform leads to the production of fatty acids. Therefore, an acidic environment is created in the colon. It can damage the walls of the intestine. The large intestine function is to balance the pH by neutralizing the acids.

For this purpose, there is the production of alkaline solutions. They effectively maintain the pH of the environment. The alkaline solutions also protect the walls of the intestine against any possible damage.

Protecting from Infections

Protection against infections is another of the large intestine functions. The food matter, passing down to the colon, may contain harmful bacteria. Meanwhile, absorption of water and vitamins takes place in this region of the gastrointestinal tract.

So, there is a possibility that these bacteria may also go into the blood stream. However, the mucous layer lining the large intestine prevents this from happening. Thereby, it provides protection against likely infections and bacterial diseases.

Antibody Production

Antibodies are substances which play an essential role in the body’s natural defense system. They provide immunity against foreign bodies and infections. The large intestine produces antibodies. They are important for enhancing the immunity of an individual.

In a nutshell, the large intestine helps in expelling the waste matter of digestion. It helps in the conversion of waste matter into feces through the absorption of water. It also produces vitamins and antibodies and protects the body from harmful bacteria.

Large intestine problems can disrupt the last phase of digestion. Such a condition will lead to issues such as constipation or diarrhea. Other serious conditions which affect the performance of the large intestine include diverticulosis, colorectal cancer and ulcerative colitis.

Therefore, it is important to maintain the health of the entire gastrointestinal tract through a balanced diet and regular workout.

About the Author

Posted by: M. Isaac / Senior writer

A graduate in biological sciences and a PhD scholar (NCBA&E University, Lahore), M. Isaac combines his vast experience with a keen and critical eye to create practical and inherently engaging content on the human body. His background as a researcher and instructor at a secondary school enables him to best understand the needs of the beginner level learners and the amateur readers and educate them about how their body works, and how they can adopt a healthier lifestyle.

Copyrights Reserves 2013-2023 by