Passing gas is a normal and natural bodily function. And while some farts don't have any smell at all, others release an impressive — and, ahem, powerful — odor.
For example: Ever let one rip and wondered why the smell reminded you of rotten eggs? Here's where that particular stench comes from, plus some tips for clearing it up.
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Why Farts Smell Sometimes
While every human body is different, we all generally release gas anywhere from five to 25 times a day, gastroenterologist Brian Wolfman, MD, says.
Seem like a lot? Consider how much air you're taking in. As Dr. Wolfman explains, we swallow air when we talk, chew and drink carbonated beverages. Because the air has to go somewhere, it comes out one end or the other: via a burp or a fart.
Occasionally, you might scrunch up your nose at the smell of your own fart. The odor of your gas is affected by what you ate coupled with the bacteria stored in your system.
The food we eat is sometimes broken down and absorbed in the small intestine, but it can pass to the colon, where bacteria break it down, Dr. Wolfman says. "These bacteria then produce certain gases, which can have a bad or even foul odor," he adds.
You may also notice a smelly scent when you're constipated. When you're stopped up, Dr. Wolfman says, your number two lingers for an extended period in your colon, where the bacteria has an extended period to create more byproducts, and thus, smellier farts.
Why Your Farts Smell Like Eggs
One of the least favorable but most commonly reported smells that the body releases is one of rotten, stinky eggs. Much like a carton that's gone bad, these can take your breath away — and definitely clear the room if you let one pass in front of others.
When this stench happens, it's likely due to having too much sulfur in your diet. As Dr. Wolfman explains, when we have meals packed with sulfur, our digestive system creates and emits hydrogen sulfide, mimicking that rotten egg smell.
He says certain foods, including cruciferous veggies like cauliflower, broccoli, kale, cabbage, Brussels sprouts and other leafy greens, could be to blame. Other high sulfur-containing foods including eggs, red meat, onions, garlic, cheese, dried fruit, nuts and beer and wine can also lead to eggy farts.
Sometimes, farts remind us of other familiar yet undesirable scents, like cabbage, sewage or burnt rubber. One reason for these is a lack of enzymes in your intestine.
Dairy can be the culprit here, since it contains the lactose protein, Dr. Wolfman says. The small intestine breaks down lactose with the enzyme lactase, turning it into glucose and beta-galactose. These simple sugars are then absorbed through the intestinal wall.
"If a person has low levels of the enzyme lactase, lactose passes along and encounters bacteria. Bacteria then ferment undigested lactose, producing methane gas, which has a foul odor," Dr. Wolfman says.
How to Prevent Smelly Farts
If you're stressed about your smelly farts, consider booking an appointment with your primary care physician who can analyze your bowel movements and frequency. With this information, you might be referred to see someone like Dr. Wolfman, should a GI tract issue be suspected.
In many cases, though, you can put an end to stinky flatulence by changing your diet. Here, Dr. Wolfman recommends a few tactics to try:
1. Up Your Fiber
Dr. Wolfman is a huge proponent of fiber, especially for those who are releasing stinky gas. The nutrient does wonders to stabilize our blood sugar levels, causing us to eat less and leading to a feeling of fulness. Plus, it benefits our cholesterol levels and overall intestinal health.
If you do decide to increase your fiber intake, you'll want to proceed with caution, since it could have the opposite affect if you move too quickly.
"Ingesting large amounts when we aren't used to it can lead to flatulence due to the bacteria byproducts," Dr. Wolfman says. "This is why, when increasing your daily fiber intake [with food] or with supplements, this should be done gradually."
You can slowly increase the amount of fiber you're eating by a couple of grams — and be sure to increase your water intake as you do so, which can help prevent constipation (and more gas).
2. Try a Low-FODMAP Diet
FODMAP stands for "fermentable oligo-, di-, monosaccharides and polyols." These are a group of carbohydrates that lead to a host of gastrointestinal complaints, including gas, Dr. Wolfman says.
Many of those high-sulfur foods fall into this category. If you have frequent, unpleasant gas, testing out a low-FODMAP diet for a month may significantly decrease symptoms.
"This can be a big undertaking, as the list is long and confusing, but once your symptoms and flatulence improve, you can reintroduce foods and assess which foods are the culprit," Dr. Wolfman says.
There are plenty of books, like The Low-FODMAP Diet Step by Step, and apps, like the Monash University FODMAP Diet, that can help you better understand what you can and cannot eat.
Is this an emergency? If you are experiencing serious medical symptoms, please see the National Library of Medicine’s list of signs you need emergency medical attention or call 911.