The Truth About Gas

Did you know  you pass gas six to 20 times a day? That number might seem excessive, but it’s true! With more than 500 different types of bacteria in your large intestine that aid in digestion and absorption of nutrients, you produce enough gas to fill one to three pints a day. Though passing gas can be a sensitive and an embarrassing topic of discussion, flatulence is a natural part of the body’s digestive process. Excessive gas and changes in the smell of your flatulence could be key signs of potential health concerns. It’s important to listen to your body and consult with your doctor if you feel you’re showing signs of digestive inconsistencies or disorders. The question is: what is normal when it comes to gas?

What is Gas?

As a natural byproduct of breaking down the food you eat, there are two reasons for gas: 

Natural Byproduct of the Digestive Process

Your digestive tract produces gas by breaking down undigested foods in the large intestine, also known as the colon. This process creates gases such as hydrogen, carbon dioxide and methane. 

Swallowing Air

Gas can also be caused by swallowing air, which happens when you chew gum, smoke, drink carbonated drinks or eat and drink large amounts too quickly. Instead of your body creating these gases (like nitrogen and oxygen) inside your colon, the flatulence caused by swallowed air comes from outside the body and travels through your digestive system. Aerophagia is the condition of swallowing very large amounts of air, which further increases gas.

Digestive Flow: How Gas Is Created

After food and liquid enter the mouth, they are transported to the stomach via the esophagus. Enzymes in the stomach then break down the food so it can be used by the body. Food and liquids continue to be broken down -- separating proteins and carbohydrates -- in the pancreas, liver and gallbladder. The small intestine becomes essential to digestion as it is where the food and liquids consumed become nutrients to be absorbed by the body. Once passed to the large intestine, waste is broken down by bacteria and yeast. Here, the bacteria digest sugars found in the waste through fermentation, which creates gas.

What Is Gas Made Of?

The gas you release in the form of a burp or flatulence is comprised of nitrogen, hydrogen, carbon dioxide, oxygen, methane and sulfur. More than 50 percent of the gas you release is nitrogen. Hydrogen, carbon dioxide, oxygen and methane make up the rest, along with sulfur, which is the source of gas’s odor.

Why Gas Smells

Sulfur compounds account for only one percent of your flatulence and causes gas to smell. Different types of sulfur compounds create different odors:

  • Hydrogen sulfide, which is very common, will produce a rotten egg smell.
  • Methanethiol will produce a smell similar to rotting vegetables or garlic.
  • Dimethyl sulfide is often described as smelling like cabbage but might add a sweetness to the overall smell of gas.

Based on the bacterial composition of an individual’s digestive tract, the smell of gas could be one sulfur compound or a combination of sulfur compounds. 

Different bacteria produce different gases. The pungency of gas is also affected by how long it takes for a body to digest food. The longer it takes your body to digest food, the more time bacteria has to cause stronger odors when the gas is released. Eating foods high in fiber and drinking plenty of water will decrease the amount of time gas resides in your colon, causing less odor. Paying attention to your flatulence frequency and pungency is important as this could be your body’s sign of digestive issues and infections.

What Foods Cause Gas to Smell More?

Since sulfur compounds produce the odor related to gas, eating foods high in sulfur compounds will increase the pungency of your flatulence. Foods high in sulfur include meat, poultry, eggs, onions, garlic, broccoli, cabbage, Brussel sprouts and cauliflower.

What Foods Cause More Gas?

Certain carbohydrates are especially difficult for your body to digest. This group of short-chain carbs is known as FODMAP, which stands for “Fermentable, Oligo-, Di-, Monosaccharides and Polyols.” Foods high in FODMAPs, such as garlic, onions, asparagus, fruits high in fructose, milk, yogurt and fruit juice, can all cause an increase in gas production.

These foods are poorly digested by the small intestine, leaving more waste to be processed by the large intestine, which is where the bacteria create gas. Individuals with normal digestive systems can eat these foods with only a mild increase in gas production. If foods high in FODMAPs cause you to feel abdominal bloating and pain, this could be an indication of intolerance to certain foods, which can produce excess gas.

Excessive Gas Could Be Sign of Digestive Disorders

Indigestion is the difficulty digesting food that leads to bloating, abdominal pain and an increase in gas. Indigestion can be caused by certain foods and drinks or due to emotional stress and anxiety. Indigestion can be diagnosed by your primary care provider, and although its symptoms are mild, it can lead to other serious disorders such as irritable bowel syndrome (IBS), ulcers or even stomach cancer.

Gastroenteritis (stomach flu) is caused by an infection that inflames the stomach and intestines. Symptoms of gastroenteritis include abdominal pain, bloating, vomiting and diarrhea.

Lactose intolerance occurs in individuals who lack the enzymes to digest sugars in cows’ milk. If the small intestine cannot digest the sugars, digestion within the large intestine takes longer, leading to excessive gas and a stronger smell.

Carbohydrate malabsorption causes abdominal pain and bloating due to an inability to digest wheat, rye and barley products. In its severe form, it is known as celiac disease.

Crohn’s disease is thought to be caused by an overactive immune system that goes beyond attacking the bacteria that it’s meant to repel, and attacking the digestive system instead. It leads to poor digestion that can create abdominal pain along with bloating, chronic diarrhea and rectal bleeding. Crohn’s disease can also cause inflammatory bowel disease (IBD), which is a progressive disease of the intestines.

Irritable Bowel Syndrome (IBS) causes excessive gas as well as stomach pain and bloating. Though the cause of IBS is unknown, it is assumed to be associated with over-activity of the digestive system.

When Does Gas Become Something You Should Talk to Your Doctor About?

Symptoms that indicate digestive problems:

  • Excessive flatulence or strong odor (accompanied by other symptoms)
  • Severe stomach/abdominal pain or bloating
  • Diarrhea
  • Constipation
  • Blood in stool
  • Nausea
  • Vomiting

Though the discussion of flatulence and gas with your doctor might be embarrassing, changes in amount or smell of flatulence could be a sign of more concerning digestive issues. It is important to pay attention to your body and know what your normal is. Your primary care doctor also needs to know your body’s normalities. The better your doctor knows your body, the better he or she will be able to recognize changes that could be early warning signs. Message your provider through My UnityPoint if you feel that your digestive system is not working properly or if you sense excess or more odorous gas.

Get Care Now with Virtual Care

Does your gas come with uncomfortable symptoms you'd like to speak to a provider about, but you don't want to leave home? See a provider from the comfort of your couch using UnityPoint Health virtual urgent care or use our online screening tool, SmartExam.