Why Do Some Farts Stink and Some Farts Don't?

Chloe Effron
Chloe Effron

Kids ask a lot of questions. mental_floss has answers. WHY?, our new series for kids and parents, tackles all types of questions children have about how the world works by providing science-based, kid-friendly content. Our answers are written with early readers (ages 4 to 7) in mind, but we think they're interesting—and educational—for everyone.

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Everyone farts, every day. But not all farts are the same. Some farts make no sound but are really stinky. Others are loud but don't smell. Some you can smell clear across the room, but others you can let out without anyone noticing. (Secret: I’m farting right now!)

The smell of your booty bomb depends on what you’ve been eating. Broccoli, cabbage, onions, eggs, and meat all contain a lot of sulfur, a chemical that helps give rotten eggs their stink. When your body digests, or breaks down, those foods, the teeny-tiny creatures in your gut called bacteria feast upon the proteins in the food that contain sulfur. This process creates smelly gases like methanethiol (METH-ain-THIGH-all). When those gases leave your body, they end up as pungent farts.


All smells are chemicals in the air that your nose can pick up. Farts are made up of chemicals like oxygen, nitrogen, hydrogen, methane, carbon, and the super villain of stinkiness: sulfur. (Sulfur is the reason that skunk spray smells so gross!) The more sulfur in your toots, the more likely they are to clear the room. You also swallow air as you eat or talk. Some of that comes out of your rear end too.


Let's talk about bacteria again. When you eat carbohydrates (CARB-oh-HIGH-drates) like potatoes, bread, and vegetables, your stomach doesn’t fully digest them. They pass into the small intestine and then the large intestine, which are really long tubes leading to your anus (where poop and farts come out). Bacteria break the carbohydrates into smaller pieces. That releases gases like hydrogen and carbon dioxide. Those gases don’t smell. But other bacteria in the gut take those odorless chemicals and make them into compounds (mixes of chemicals) that do smell. Hydrogen sulfide (HIGH-dro-jen SULL-fide) is the smelliest of the gases that might come out of your butt.

For more fart science, check out AsapSCIENCE’s illustrated video explanation of why your farts don’t smell as bad as other people’s do. 



Wayfair’s Fourth of July Clearance Sale Takes Up to 60 Percent Off Grills and Outdoor Furniture

Wayfair/Weber
Wayfair/Weber

This Fourth of July, Wayfair is making sure you can turn your backyard into an oasis while keeping your bank account intact with a clearance sale that features savings of up to 60 percent on essentials like chairs, hammocks, games, and grills. Take a look at some of the highlights below.

Outdoor Furniture

Brisbane bench from Wayfair
Brisbane/Wayfair

- Jericho 9-Foot Market Umbrella $92 (Save 15 percent)
- Woodstock Patio Chairs (Set of Two) $310 (Save 54 percent)
- Brisbane Wooden Storage Bench $243 (Save 62 percent)
- Kordell Nine-Piece Rattan Sectional Seating Group with Cushions $1800 (Save 27 percent)
- Nelsonville 12-Piece Multiple Chairs Seating Group $1860 (Save 56 percent)
- Collingswood Three-Piece Seating Group with Cushions $410 (Save 33 percent)

Grills and Accessories

Dyna-Glo electric smoker.
Dyna-Glo/Wayfair

- Spirit® II E-310 Gas Grill $479 (Save 17 percent)
- Portable Three-Burner Propane Gas Grill $104 (Save 20 percent)
- Digital Bluetooth Electric Smoker $224 (Save 25 percent)
- Cuisinart Grilling Tool Set $38 (Save 5 percent)

Outdoor games

American flag cornhole game.
GoSports

- American Flag Cornhole Board $57 (Save 19 percent)
- Giant Four in a Row Game $30 (Save 6 percent)
- Giant Jenga Game $119 (Save 30 percent)

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How the Scientist Who Invented Ibuprofen Accidentally Discovered It Was Great for Hangovers

This man had too many dry martinis at a business lunch.
This man had too many dry martinis at a business lunch.
George Marks/Retrofile/Getty Images

When British pharmacologist Stewart Adams and his colleague John Nicholson began tinkering with various drug compounds in the 1950s, they were hoping to come up with a cure for rheumatoid arthritis—something with the anti-inflammatory effects of aspirin, but without the risk of allergic reaction or internal bleeding.

Though they never exactly cured rheumatoid arthritis, they did succeed in developing a nonsteroidal anti-inflammatory drug (NSAID) that greatly reduced pain of all kinds. In 1966, they patented their creation, which was first known as 2-(4-isobutylphenyl) propionic acid and later renamed ibuprofen. While originally approved as a prescription drug in the UK, it soon became clear ibuprofen was safer and more effective than other pain relievers. It eventually hit the market as an over-the-counter medication.

During that time, Adams conducted one last impromptu experiment with the drug, which took place far outside the lab and involved only a single participant: himself.

In 1971, Adams arrived in Moscow to speak at a pharmacology conference and spent the night before his scheduled appearance tossing back shots of vodka at a reception with the other attendees. When he awoke the next morning, he was greeted with a hammering headache. So, as Smithsonian.com reports, Adams tossed back 600 milligrams of ibuprofen.

“That was testing the drug in anger, if you like,” Adams told The Telegraph in 2007. “But I hoped it really could work magic.”

As anyone who has ever been in that situation can probably predict, the ibuprofen did work magic on Adams’s hangover. After that, according to The Washington Post, the pharmaceutical company Adams worked for began promoting the drug as a general painkiller, and people started to stumble upon its use as a miracle hangover cure.

“It's funny now,” Adams told The Telegraph. “But over the years so many people have told me that ibuprofen really works for them, and did I know it was so good for hangovers? Of course, I had to admit I did.”

[h/t Smithsonian.com]