It's both funny and embarrassing; perfectly natural, yet offensive. Sometimes it's even painful. It assails our senses with its repugnant smell, while providing a much-needed release. It can announce its presence with an unapologetic, thunderous sound or a lingering, comedic melody. Sometimes, much to the relief of the perpetrator, it can stealthily go unnoticed. It's considered both rude and crude — something you simply shouldn't do around other people.

The act goes by many names — cutting the cheese, blowing a raspberry, letting it rip, passing gas, breaking wind and tooting. But it is most known as farting. And, while we are still small children, we develop a fascination with one of our body's most basic functions — the accumulation and expelling of gas through the rectum, known as flatulence.

But what causes flatulence?

"Flatulence is a normal physiological process, which occurs when the bacteria in the large intestine (colon) metabolize things in our diet that we can't metabolize. If we didn't pass gas, we would explode," says Dr. Eamonn Quigley, a gastroenterologist with Houston Methodist Gastroenterology Associates.

Our bodies have two processes to remove gas: belching (or burping) and flatulence. Belching is mostly caused by the air we swallow, and it releases gas from the upper GI tract — the stomach and the esophagus. Flatulence occurs in the lower gastrointestinal (GI) tract.

Why do farts smell so bad?

Most gas passed during flatulence goes unnoticed because there isn't a smell. It may contain odorless gases, such as nitrogen, oxygen, hydrogen, carbon dioxide and methane, but a small portion includes hydrogen sulfide, which causes it smell like rotten eggs. Think of hydrogen sulfide as the waste of the microbes helping you digest the indigestible. Then, there are other factors contributing to smelly farts, including compounds that are byproducts from meat digested, and whether there is feces present in the rectum when flatulence occurs.

What foods and drinks cause gas?

"When a patient complains of excessive gas, one of the first things we look at is the patient's diet," explains Dr. Quigley.

Here are some foods associated with causing flatulence:

• Sugars, such as glucose (table sugar), lactose (milk sugar) and fructose (fruit sugar)
• Beans, including black beans, kidney beans and pinto beans
• Beverages, such as apple juice and milk
• Dairy products, such as cheese and ice cream, as well as food with added lactose
• Fruit, such as apples, pears and prunes
• Sugar alcohols commonly found in sugar-free candies and gum, including sorbitol, mannitol and xylitol
• Vegetables, such as asparagus, broccoli, cabbage, Brussels sprouts, cucumbers, onions and carrots
• Whole grains, including bran and whole wheat
  
  

Foods that can cause smelly gas include:

• Asparagus
• Beans
• Cabbage
• Coffee
• Dairy products
• Eggs
• Onions
• Prunes
  
  

"Some people have difficulty metabolizing sugars and carbs. If the patient has a condition, such as irritable bowel syndrome (IBS), then we might recommend the patient adopt a low FODMAP diet," says Dr. Quigley.

FODMAPs (fermentable oligosaccharides, disaccharides and monosaccharides, and polyols) are the types of carbohydrates that can create digestive issues, such as gas, abdominal pain, bloating, constipation and diarrhea.

When should I see a doctor about flatulence?

"When it becomes distressing is when you should seek help," says Dr. Quigley. "If you notice changes in the amount and frequency of gas passed, as well as abdominal pain, then it is time to talk to a doctor."

What conditions cause excessive gas?

Conditions that create excess flatulence do so through various mechanisms. Lactose intolerance and celiac disease cause gas and bloating because the body has problems digesting carbs. Other conditions, such as abdominal adhesions, abdominal hernia and dumping syndrome, cause changes in how gas moves through the intestines. Also, diabetics can develop gastroparesis, which causes abnormal functioning of the stomach, with one of the symptoms being excessive gas. Also, check the list if side effects of both prescription and over-the-counter medications if you have noticed an increase in gas. Some medications, such as ibuprofen and antacids, may cause an increase in flatulence.

Why does having gas hurt?

"When people feel bloated and experience gas pain, it is not necessarily caused by a person having more gas, but by the gas becoming trapped and unable to move through the intestines properly."

Is holding a fart in bad for you?

It's going to come out one way or another. Holding in gas because you are in public only causes it to build up, resulting in abdominal distension, a feeling of being bloated, and possibly abdominal pain. The gaseous buildup may cause you to lose control over what could have been a nice, quiet and unnoticeable experience, and turn it into an epically embarrassing and possibly loud incident. So, unclench your cheeks and let it release — preferably in a nearby restroom.

Does the act of farting spread germs?

In case, you were worried about the internet rumors or debunked initial reports that you can catch COVID-19 from someone passing gas, you can't.

"There is no evidence that you can spread germs through flatulence, unless feces is present," says Dr. Quigley.

If it gives you comfort, think of your clothing as a mask for your bottom. Just to be safe, keep your pants on, for all our sakes.

Fun Fart Facts

• Women may actually fart more than men. However, they are typically more discreet about doing it.
• Humans pass gas between 13 to 21 times a day.
• Farts can be flammable, if they contain hydrogen and methane. (Warning: Do not try to test under any circumstances.)
• According to an NBC News report, upon release, farts can travel about 10 feet per second, or approximately 6.8 miles per hour.
• A scientist who studies flatulence is called a flatologist.
• The oldest recorded joke is an ancient Sumerian fart joke that dates back to 1900 BC.