There are several interconnected causes behind flatulence odor, with the smell of flatulence boiling down to efficiency of the digestive process and what someone eats. The actual odor-causing compounds in farts are produced by bacteria in the colon in the process of breaking down food. These bacteria are beneficial and welcome residents of the intestinal tract, as they break down food into forms the body can absorb.
Everyone has slightly different gut flora and consequently, the odor of flatulence is quite variable from person to person. Most of the strong smells associated with it are caused by sulfur compounds and methane, common byproducts of digesting foods like meat, eggs, and members of the broccoli family. Some people have a higher concentration of organisms known for producing strong smelling gases, and therefore may experience more odor than others.
Efficiency also plays a role. The longer foods sit in the digestive tract, the more they ferment. Fermentation generates gases, some of which have a strong smell, and can cause an increase in odor. In addition, people with food allergies and intolerances tend to have stronger smelling flatulence as a result of inefficiency in their digestive tracts and partial fermentation of the foods that their bodies cannot digest.
There are some things people can do to address flatulence odor. Changing the diet can help, especially if a person has suspected food intolerances. It is also possible to take medications like charcoal to reduce the frequency of farting. Although this may not resolve the odor issue, it will reduce the risk of social embarrassment by limiting the chances of releasing gas in an environment where it might be an issue. People with unresolved digestive conditions like irritable bowel disease may find that treatment for their conditions will help fix the flatulence problem.
Many farts are odorless and may not even be noticed, as the bowels are continually expressing gas. The bulk of the gas is caused by air swallowing, not gas production in the intestines, and is relatively odor-free. People who notice a change for the worse in their flatulence odor may want to consider discussing the matter with a medical professional. Aside from being somewhat unpleasant, it can be an indicator that something is wrong with the gut flora or the patient's intestines. A medical evaluation can determine if there is a problem and allow a healthcare professional to develop a treatment plan to address the issue, as well as resolving the odor issues.