The colon is an incredible organ that makes up 1/5 of our digestive tracts. It helps us absorb vitamins like B12; create nutrients like vitamin K, biotin, and short-chain fatty acids; regulates water and electrolytes in our bloodstreams, and eliminates the byproducts of cellular metabolism and hormone production.
If you have questions about the colon, though, you’re not alone. Most people are never taught about the wide array of functions the colon performs for our health each day. Did you know, for example, that the colon and its functions help to regulate bone health, immunity, blood clotting, and more?
In this article, we’ll cover what the colon is, how it impacts health, and how you can keep your colon healthy with nutrition, lifestyle changes, and regular screening.
Anatomy And Function Of The Colon
The colon is a hollow tube of muscular tissue that is approximately five feet long in the average adult. This tube is divided into several sections: the cecum and ileocecal valve; the ascending colon, transverse colon, descending colon, and sigmoid colon, which terminates at the rectum.
Each part of the colon has a different role to play in human health. The anatomy of each part of the colon helps to give it special abilities. For example, the ascending, transverse, and descending colon contains chambers called haustra, which look like small pockets. The word haustra comes from the Latin word for container or bucket—and that’s how they look! Haustra hold the digested food and water mixture that came from the small intestines for long enough periods until the colonic membrane can extract the nutrients it needs before allowing the food to move through the rest of the colon and out of the body as stool.
Haustra are also home to bacteria and other microorganisms that help to extract nutrients from food. Certain bacteria, for example, produce biotin and vitamin K from the food we eat. Other bacteria ferment fibers to produce short-chain fatty acids like butyrate, which in turn fuel cellular metabolism in the colonic membrane.
Each haustrum is lined with absorptive mucosa which is composed of cells called colonocytes. The colonocytes help to regulate potassium, sodium, water, chloride, bicarbonate, and other electrolyte concentrations both inside and outside of the colon. This, in turn, helps us to regulate the electrolyte balance in our bloodstream.
If we zoom out from looking at the ascending, transverse, and descending parts of the colon, we can see the very first part of the colon, which is called the cecum. It’s located just above the right hip bone, and you may even be able to feel it and move it around when it’s full of digesting foods. It will feel like a small water balloon when it’s very full.
The cecum is attached to the appendix and contains a valve that allows digested food to pass from the small intestines and into the bloodstream. This valve is called the ileocecal valve and is the site of two important things in the body. First, it’s where our vitamin B12 is absorbed if we have a healthy gut. Second, it’s an important back-stop that prevents the backward flow of items from the large intestine into the small intestine. We’ll cover more of this below in the colonic disorders section, but just know that when this valve doesn’t work properly, you won’t feel well and you’re more likely to experience something called small intestinal bacterial overgrowth (SIBO), among other issues.
As you can see, the colon has many parts, layers, and anatomical structures that help it perform each of its important functions.
How The Colon Impacts Overall Human Health
The colon is responsible for nutrient absorption and production, as well as the elimination of wastes from the body. To say that these processes are critical for optimal human health is a complete understatement!
The Colon Helps to Produce Vitamin K and Biotin
The colon is home to many bacteria that manufacture vitamin K and biotin from the foods we eat. Vitamin K is required for the synthesis of several clotting factors, which help our blood form scabs and stop bleeding when a wound occurs. Certain forms of vitamin K (like K2) are also involved in bone turnover and calcium metabolism. When food sources of vitamin K, like natto and leafy green vegetables, are inadequate in the diet, bacterial production of vitamin K becomes important for preventing symptoms of nutritional deficiency.
Biotin is required for blood sugar management and the health of hair, skin, and nails, and for adequate maintenance of zinc. Similar to vitamin K, it’s manufactured by colonic bacteria and can help fill the gaps if our nutritional intake of biotin falls short. Biotin deficiency can lead to rashes, depression, seizures, hair loss, nail issues, and more.
For all of these reasons, we want a colon that contains enough healthy bacteria.
Absorption of Minerals and Fluid
The colon helps to regulate hydration by absorbing water from the foods we eat. Additionally, the colonic membrane pulls electrolytes like potassium, calcium, sodium, chloride, and more from foods and into our bloodstreams. These minerals are used to create electricity in our nervous systems, catalyze enzymatic reactions that create cellular energy, and maintain fluid balance and blood pressure in our cardiovascular system. You can imagine that a deficiency in any one of the minerals—whether due to poor nutrition or poor colonic health—could have a powerful, wide-reaching, and profound impact on overall wellbeing, but particular for heart and nerve health.
Elimination of Toxins
Something I wish more people knew about the human body is that, while the liver filters toxins from the bloodstream, it’s actually the colon that eliminates those toxins from the body. Our livers process the waste products of enzymatic reactions in our bodies, put them through phase one and phase two digestion in the hepatocytes, and then excrete the waste product into bile, which is then excreted into the digestive tract. Once in the digestive system, those bile-bound-toxins bind to fiber. That fiber and bile combination is supposed to then be packaged into stool once it reaches the colon and then excreted routinely—at least once a day—to keep our body’s toxic burden low. When your colon is healthy and you’re eating the right foods—this happens naturally.
What Can Go Wrong with Colonic Health
Inflammatory Bowel Diseases (IBD)
Crohn's and ulcerative colitis are inflammatory conditions that affect colonic membranes. They can lead to ulcers, bleeding, nutrient malabsorption, pain, and more. When colonic membranes are chronically inflamed and damaged, this can lead to nutrient deficiencies over time. These conditions also increase the risk of colon cancer if left untreated.
Colon Cancer
Colorectal cancer is the third most common type of cancer worldwide. An estimated two million people across the globe had colon cancer in 2020. Risk factors for colon cancer include low-fiber diets, inactivity, alcohol consumption, being overweight, and low vitamin D status. All of these risk factors can impact DNA synthesis in the colon and other tissues. Because abnormal DNA production and regulation is the root cause of tumor initiation and growth, keeping DNA production healthy in the colon is important.
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