Butyric Acid, Gut Bacteria, and Colon Health

Updated on July 22, 2017
AliciaC profile image

Linda Crampton is a writer and teacher with a first class honors degree in biology. She often writes about the scientific basis of disease.

Butter contains butyric acid.
Butter contains butyric acid. | Source

An Important Chemical for Health

Our large intestine hosts a huge population of bacteria that have many effects on our lives. Most of these effects are believed to be beneficial. Some of our intestinal bacteria convert the soluble fiber and resistant starch present in undigested food into short-chain fatty acids. One of these fatty acids is butyric acid, which has health benefits in the large intestine. It helps to maintain a healthy intestinal lining and may reduce symptoms of inflammatory bowel disease. It may also lower the risk of colon cancer, though this benefit is less certain.

The colon is the longest section of the large intestine and houses the greatest number of gut bacteria. The amount of butyric acid formed in the colon depends on which bacteria live there and on how much soluble fiber and resistant starch is present. It’s also determined by the size of the bacterial population that is able to produce the butyric acid and by how long the fiber or starch stays in the colon. The study of gut bacteria and their needs and effects is very important. Keeping the bacteria healthy could also help to keep us healthy.

The Digestive or Gastrointestinal Tract


The Digestive Tract, Digestion, and Gut Bacteria

When food is swallowed, it passes through a tube called the digestive or gastrointestinal tract. The tube starts at the mouth and ends at the anus. The food is gradually digested as it travels. Digestion is the process in which food is broken down into small particles that can be absorbed.

The food that we eat gives us nutrition, but it also feeds the bacteria in our intestine. Most of these bacteria live in the colon. The small intestine and the rectum also contain bacteria, however. The concept of feeding both ourselves and our helpful gut bacteria is gradually becoming more popular. "Gut" is another word for the digestive tract or the intestine.

The general processes that occur in the digestive tract are as follows.

  • Food is digested in the mouth, stomach, and small intestine.
  • The products of digestion are absorbed through the lining of the small intestine into the bloodstream.
  • The blood carries the nutrients to where they're needed.
  • The indigestible food passes from the small intestine into the large intestine.
  • Bacteria in the large intestine act on the food residue, producing a variety of chemicals.
  • The lining of the large intestine absorbs water, salts, and vitamins.
  • The remaining food residue is released from the large intestine through the anus as feces (or stool).

Studying Gut Bacteria in the Intestinal Microbiome

The Large Intestine and the Colon

The bacterial community in the colon is often referred to as the intestinal microbiome. Researchers are discovering that colon bacteria are very active. Many of them are beneficial. Some appear to be neutral and a few are harmful. In a healthy gut, the effects of the helpful bacteria overshadow the effects of the harmful ones. The study of gut bacteria is exciting because the bacteria may have profound effects on our lives and health.

The large intestine is made of the ascending colon, the transverse colon, the descending colon, and the rectum. Most of the bacteria live in the three sections of the colon, which are collectively known as simply "the colon".

Peas are a good source of soluble fiber.
Peas are a good source of soluble fiber. | Source

What Is Soluble Fiber?

The human body can’t digest soluble fiber. This doesn't mean that the fiber is useless, however. In fact, it has health benefits. It dissolves in the water present in the digestive tract, forming a gel. This gel lowers the level of LDL cholesterol (the so-called “bad” cholesterol) in the blood. It also lowers the blood sugar level. Another health benefit of soluble fiber is that it can be fermented by certain colon bacteria to produce butyric acid.

Good sources of soluble fiber include barley, oatmeal, beans, peas, carrots, apples, pears (not including the peel), and many other types of fruits and vegetables. The peels of fruits and vegetables contain insoluble fiber. The body can't digest this material. Like soluble fiber, however, it has benefits, including bulking up the stool and relieving constipation.

Substances that cause butyric acid to be made by gut bacteria are said to be butyrogenic. The bacteria that make the butyric acid are also said to be butyrogenic.

Soluble and Insoluble Fiber

What Is Resistant Starch?

Resistant starch is starch that we are unable to digest or that we digest very slowly. The amount of resistant starch in a food depends not only on the identity of the food but also on factors such as whether the food is cooked or raw, whether it's cooked and then cooled (which changes the nature of the starch), and its degree of ripeness. Some good sources of resistant starch are cooked potatoes that have been chilled, rice, pasta, unripe bananas, legumes such as navy beans and lentils, and high-amylose corn.

The glycemic index is a number that represents the ability of a food to raise the level of glucose in the blood. Glucose is the technical name for blood sugar. In general, food with a high glycemic index is considered to be bad, since it may lead to an increase in body fat and a higher risk of diabetes and heart attacks.

Resistant starch has little effect on blood sugar level and is therefore classified as a low glycemic substance. The glycemic index of a food containing resistant starch depends on the proportion of resistant starch to higher glycemic carbohydrates in the food. Some colon bacteria can ferment resistant starch to make butyric acid, which is another benefit of the substance.

Green bananas contain resistant starch. They're popular in some cuisines.
Green bananas contain resistant starch. They're popular in some cuisines. | Source
This is the structural formula for a butyric acid molecule. The acid group is shown on the right side of the formula.
This is the structural formula for a butyric acid molecule. The acid group is shown on the right side of the formula. | Source

What Is Butyric Acid?

A fat molecule is composed of a glycerol molecule joined to three fatty acid molecules. The whole structure is sometimes known as a triglyceride. Butyric acid, also called butanoic acid, is a fatty acid present in some triglycerides. It's released when the fat is broken down.

Some articles about butyric acid refer to butyrate. Butyric acid and the butyrate ion have slightly different structures, although they are very similar. The final hydrogen atom shown in the formula above has been lost in a butyrate ion, which is also called a butanoate ion. The ion can form substances called butyrate salts.

Butyric acid is a short-chain fatty acid, or SCFA, as opposed to a medium-chain or long-chain fatty acid. SCFAs have an acid group (COOH) at one end of their molecule and a “tail” or chain containing fewer than six carbon atoms attached to the acid group.

Some foods contain relatively high concentrations of butyric acid, including butter and parmesan cheese. Butyric acid reportedly makes up 3% to 4% of butter. Kombucha tea also contains the acid. The kombucha culture is a mixture of bacteria and yeasts. If the culture is placed in tea that has been sweetened with sugar and the microbes are allowed to ferment the sugar, a variety of chemicals are produced, including butyric acid.

Parmesan cheese contains butyric acid. In Europe, parmesan cheese is another name for Parmigiano-Reggiano cheese.
Parmesan cheese contains butyric acid. In Europe, parmesan cheese is another name for Parmigiano-Reggiano cheese. | Source

A Smelly Chemical

Butyric acid has a very unpleasant odor and smells like vomit. In fact, the chemical is present in vomit. When butter becomes rancid, enzymes produced by bacteria release the butyric acid from the fat molecules, producing the typical rancid smell. The acid got its name from “butyrum”, the Latin word for butter, which in turn was based on a similar Greek word.

Concentrated butyric acid must be handled very carefully, not only because of its nauseating smell but also because it’s corrosive. At low concentrations, however, the acid is safe. In very low concentrations, it’s used as a flavoring agent in food.

Butyrum is the Latin word for butter and gave rise to the term butyric acid.
Butyrum is the Latin word for butter and gave rise to the term butyric acid. | Source

Potential Health Benefits of Butyric Acid

Butyric acid is a saturated fatty acid. Saturated fats contain saturated fatty acids and have a reputation for creating health problems if eaten in excess. These problems include increasing the amount of LDL cholesterol in the blood. A high cholesterol level may lead to fatty plaque deposits in arteries and increase the risk of a heart attack or a stroke. Excess cholesterol may also increase the risk of some types of cancer. Researchers are discovering that not all saturated fats produce these effects, however. Butyric acid and other short-chain fatty acids actually have health benefits.

Butyric acid is the main food source of the colonocytes, which are cells in the lining of the colon. The chemical supports the colonocytes, helping them to function properly and maintaining the integrity of the intestinal lining.

Butyric acid may help people suffering from Crohn’s disease and ulcerative colitis. These disorders are classified as inflammatory bowel diseases, or IBD. Butyric acid enemas have reduced colon inflammation symptoms in some IBD patients. Further exploration of this effect is needed, however.

Probiotics are living bacteria or yeasts that provide health benefits when ingested. One problem faced by probiotic companies is that the microbes that they provide must not only survive their journey through the digestive tract but also stay in the intestine long enough to be beneficial.

Butyric Acid Enemas and Probiotics

Butyric acid enemas are sometimes offered to people with IBD. Unfortunately, the enemas smell bad and patients are not always willing to undergo the treatment. Another problem with an enema is that the butyric acid doesn’t stay in the colon for very long.

Researchers are investigating the use of probiotic supplements containing bacteria that can make butyric acid. If the probiotic bacteria multiply in the colon and become permanent inhabitants, the patient will have a continuous supply of a potentially useful chemical. A probiotic supplement should be much more pleasant to take than an enema.

Cooked and then chilled potatoes contain resistant starch, which increases the amount of butyric acid in the colon.
Cooked and then chilled potatoes contain resistant starch, which increases the amount of butyric acid in the colon. | Source

Butyric Acid and Colon Cancer

Apoptosis—programmed cell death—is a normal process in cells. For example, cells may be stimulated to undergo self-destruction if their DNA is damaged so severely that it can’t be repaired or if there are too many cells in an area. Cancer cells do not undergo apoptosis and continue to multiply, however.

In some experiments with lab animals, butyric acid has been found to inhibit multiplication of cancerous colonocytes and stimulate apoptosis in the cells. Not all experiments concerning butyric acid and cancer have shown benefits, however. Nevertheless, the preliminary research results are intriguing.

The study of butyric acid or butyrate in relation to cancer is difficult. The surrounding environment seems to be very important in determining the effect of the chemical in the intestine. More research is needed before scientists agree that butyric acid can prevent or treat colon cancer in humans.

Oatmeal contains soluble fiber, which increases the amount of butyric acid in the large intestine.
Oatmeal contains soluble fiber, which increases the amount of butyric acid in the large intestine. | Source

Anyone who wants to use butyric acid in larger amounts than found in food should consult a doctor. Substances used as medications often have side effects as well as benefits. The side effects are sometimes serious.

Increasing the Amount of Butyric Acid in the Colon

One plan for someone hoping to increase the amount of butyric acid in their colon is to eat foods that are high in soluble fiber and resistant starch. These substances should act as nutrients for appropriate gut bacteria. Since butter and parmesan cheese contain butyric acid, they could be used to support gut health as well. However, these foods also contains longer chained saturated fats, some of which may be unhealthy.

The recommendation from the majority of nutritionists and health agencies is to limit the amount of saturated fat in our diet. The suggestions for fat consumption in the American Heart Association article mentioned below are standard ones. The association says that research over many years has shown that saturated fats are bad for the cardiovascular system.

In the last few years, however, some dissenting opinions about saturated fats have arisen. Some researchers disagree with the idea that they are bad for the circulatory system and say that their demonization is wrong. Hopefully the situation will be clarified soon. The type of fat that we eat is an important topic for those of us that are concerned about our health.

Wheels of parmesan cheese maturing in a factory
Wheels of parmesan cheese maturing in a factory | Source

The Importance of Supporting Gut Bacteria

Maintaining a helpful intestinal microbiome is very important. Scientists are learning more about the functions of bacteria in the colon and about how to add new ones to the intestinal population. It may one day be possible for us to eat or drink probiotic supplements that supply us with bacteria that will prevent or treat specific health problems. Until then, it seems like a good idea to support our present gut bacteria so that they can make substances that may provide significant health benefits, including butyric acid.


  • Załęski A, Banaszkiewicz A, Walkowiak J. Butyric acid in irritable bowel syndrome. Przegla̜d Gastroenterologiczny. 2013;8(6):350-353. doi:10.5114/pg.2013.39917 (Includes a reference relating to the effect of butyric acid on intestinal inflammation in humans)
  • Butyric acid and intestinal inflammation in mice from nature.com (Also includes references relating to the treatment of IBD in humans with butyric acid)
  • Butyrate and colorectal cancer from the NIH (National Institutes of Health)
  • American Heart Association recommendations for saturated fat intake

Questions & Answers

    © 2011 Linda Crampton


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      • AliciaC profile image

        Linda Crampton 18 months ago from British Columbia, Canada

        Thanks for the comment, Gershon. Butyric acid is absorbed into the body through the lining of the small intestine, but based on the research reports that I've seen the chemical is usually studied with respect to its effects on the large intestine. Encapsulated supplements containing butyric acid are currently available. They're designed to release their contents in the intestine, but I don't know how effective they are.

      • profile image

        Gershon 19 months ago

        I appreciated your article. Thanks! Can you tell me...what type of effect should butyric acid have on the small intestines? Any? Also, any experience with butyric acid supplementation or familiar with its effects?

      • AliciaC profile image

        Linda Crampton 23 months ago from British Columbia, Canada

        What an interesting question! As far as I know, the answer is no. Only a small amount of butyric acid enters the bloodstream from the intestine. Most of it is used by cells lining the colon. Butyric acid can cause difficulty in breathing when it's inhaled, but only if it's very concentrated.

      • profile image

        Jackie 23 months ago

        While consuming these saturated fats that produce butyric acid, is it possible for someone to emit an odor that can cause another person to have a reaction involving difficulty breathing, tight chest, and wheezing?

      • AliciaC profile image

        Linda Crampton 5 years ago from British Columbia, Canada

        Hi, Paolo Pezzi. Thanks for the comment. Most nutrition experts recommend that we limit our consumption of foods containing a high level of saturated fat, because there is a lot of evidence that these foods contribute to health problems if they are eaten (or drunk) in a large amount. The problem is that there are many types of saturated fatty acids in foods, and while some are harmful others seem to be beneficial! Omega-3 fats are considered to be very good for us, though.

      • profile image

        Paolo Pezzi 5 years ago

        Very good article! Only a consideration: do not limit milk derivates for saturated fatty acids but integrate the diet with omega-3 (like fish or linseed oils). Milk cream is better than butter for a higher content in phospholipids (lecithines).

      • AliciaC profile image

        Linda Crampton 5 years ago from British Columbia, Canada

        Thank you, PaisleeGal. I appreciate the comment and the vote!

      • PaisleeGal profile image

        Pat Materna 5 years ago from Memphis, Tennessee, USA

        Alicia.. good article and useful information. Thanks for sharing. Voted up!

      • AliciaC profile image

        Linda Crampton 6 years ago from British Columbia, Canada

        Thank you so much, prasetio! Best wishes - I hope that this week will be a great one for you.

      • prasetio30 profile image

        prasetio30 6 years ago from malang-indonesia

        Hi, Alicia. I always learn something new from you. Thanks for share with us. I'll press all button here, except funny. Take care!

        Blessing and hugs,

      • AliciaC profile image

        Linda Crampton 6 years ago from British Columbia, Canada

        Thanks, CMHypno! I eat bananas that are slightly green, too. I don't like bananas when they are very ripe, unless they are mixed with other ingredients in a smoothie.

      • CMHypno profile image

        CMHypno 6 years ago from Other Side of the Sun

        Thanks for the great information AliciaC. I have always preferred my bananas on the green side, so I am glad to know that I have been making a healthy choice!

      • AliciaC profile image

        Linda Crampton 6 years ago from British Columbia, Canada

        Thanks for the visit and the comment, Peggy W. I get probiotics from yogurt, which I eat frequently. I buy brands of yogurt that contain live bacterial cultures. I only eat butter occasionally (I like it too much to eat in moderation!) so I'm not getting butyric acid from this source. I hope that my gut bacteria are making butyric acid for me!

      • Peggy W profile image

        Peggy Woods 6 years ago from Houston, Texas

        I have been hearing more and more about probiotics. Do you take some on a daily basis or just rely upon food sources? If the former...any certain brands? You mentioned butter. What about yogurt? Thanks for this interesting hub!

      • AliciaC profile image

        Linda Crampton 6 years ago from British Columbia, Canada

        Hi, b. Malin. I hope you feel better soon. Not being sick for years is very impressive! Thank you so much for your comment.

      • b. Malin profile image

        b. Malin 6 years ago

        I'm just getting over the Flu...I haven't been sick in YEARS...SO, needless to say how very helpful this Hub was to me. Thanks so much for sharing.