The human colon is a reservoir for different bacteria. These bacteria make up the healthy natural flora that synthesizes vitamin k and plays a role in maintaining the body's normal physiology. These bacteria are essential for good health.
Naturally, these bacteria produce several gases, including oxygen, carbon dioxide, hydrogen, and methane. Nitrogen from the atmosphere also passes through the colon.
Most of the gases produced by intestinal bacteria are odorless. However, some bacteria produce tiny amounts of sulfide gas, which can smell badly.
These bacteria rely on sulfur-containing compounds and medicines and produce gases with bad smells.
Normal range of flatus:
- Normally, intestinal bacteria produce one pint to several quarts of colon gas daily.
- Intestinal gases are produced more in men than women, and an adult has 10-13 flatus episodes per day on average.
- Smokers produce more quantities of colon gas than nonsmokers.
- The flatuses of beer drinkers often smell quite bad due to the sulfur content in beer(1).
Plants contain two main types of dietary fibers:
- Soluble fibers
- Insoluble fibers
Many plants have both types of fibers in variable proportions.
Insoluble fiber doesn't dissolve in water and passes through the small intestine undigested. As a result, it increases the bulk of stools and improves GI tract motility. It also reduces the risk of colon cancer due to its positive effects on motility(3).
It makes stool softer, bulkier, and easier to pass, all of which reduce the risk of constipation(4). In addition, it also helps us maintain a healthy weight and is helpful in controlling diabetes.
Since it passes through the colon, intestinal bacteria do not ferment it, and therefore it doesn't cause the production of colon gas and flatus.
Foods rich in insoluble fiber are:
|wheat bran||Brazil nuts|
|vegetables and fruit, especially the skins||brown rice|
Soluble fiber dissolves in water and is fermented by intestinal bacteria. It acts as a food source for intestinal flora and helps maintain the healthy bacterial population in the colon. However, its fermentation causes the production of colon gases that are discharged out as flatus.
Foods rich in soluble fiber are:
|apples, oranges, grapefruit, peaches, concord grapes||carrots|
|prunes, pears, cranberries||psyllium (found in supplements and some cereals)|
Sulfate and flatus odor
Sulfate is the primary culprit for bad-smelling flatus. It enters our digestive tract from multiple sources such as:
- Natural water contains a small amount of sulfate. Depending upon water contamination, the amount can increase.
- Beverages such as beer and wine contain sulfates.
- Animal proteins, fish, and poultry products contain sulfates.
- Some people with joint problems use supplements such as chondroitin sulfate, glucosamine sulfate, etc.
Some other foods rich in sulfates are:
|cruciferous vegetables – broccoli, cauliflower, brussel sprouts, cabbage||prunes|
|dried fruits such as apples, mangos and apricots|
The 1st step in avoiding foul-smelling flatus is to control your sulfate intake.
Colon acidity and prebiotics
Colon bacteria that produce bad-smelling gases can't grow in acidic environments. Therefore, we typically recommended the use of prebiotic supplements to acidify your colon.
Final flatus factoids
Commonly described factoids about flatus are:
- If you pass little or no flatus, you may not be getting sufficient soluble fiber in your diet.
- The act of chewing gum may increase flatus because you swallow more air during the chewing process.
- Beans contain some carbohydrates that increase colon gas production.
- Eating fast may increase colon gas as more air is swallowed.
- Reducing sulfur in your diet and prebiotic supplements are effective tools to control bad-smelling flatus.
Colon gas production can be controlled by adjusting soluble fiber intake to optimal levels.
The smell of flatus can be controlled by limiting sulfate in your diet and consuming prebiotic supplements.
- Bolin TD, Stanton RA. Flatus emission patterns and fibre intake. Eur J Surg Suppl. 1998;(582):115–8.
- Pixabay.com. Available from: https://pixabay.com/photos/breads-cereals-oats-barley-wheat-1417868/
- Soliman GA. Dietary Fiber, Atherosclerosis, and Cardiovascular Disease. Nutrients. 2019 May 23;11(5).
- Treatments for Constipation: A Review of Systematic Reviews. Ottawa (ON): Canadian Agency for Drugs and Technologies in Health; 2014.
- Pixabay.com. Available from: https://pixabay.com/photos/fruits-fresh-basket-fresh-fruits-1114060