Why Do Some Farts Smell Worse Than Others?

Publish Date
Thursday, 13 October 2016, 2:32PM

It is a mysterious science: why do some farts smell worse than others?

Everyone farts between 10 and 20 times a day. And though it may seem like an embarrassing reality we'd rather not live with, each fart is a sign of a healthy digestive system.

However, no one fart is the same - and the smelliness can tell you something about your inner health.

Sometimes it may be loud and odorless, or smelly. Sometimes it's really smelly. Sometimes it's silent but deadly.

For some people they're always as smelly as rotten eggs, for others they tend to be odorless.

Enter Dr Myron Brand to explain what it all means.

Dr Brand spoke to Thrillist to reveal some little-known gems about our gassiness.

Bad news if you're on a diet: Dr Brand says healthy eating makes the scent worse.

But not to worry, he says.

"Smelly odor is not bad, it's just a function of what you're eating and what your bacteria is doing inside your gastrointestinal tract. Everyone is different."

Asked if smelly farts are a bad thing, Dr Brand responds: "Nope. It just means you're eating food and digesting it well - and there's more room on the outside than on the inside."

What is a fart?

A large proportion of the gas we let off during the day is carbon dioxide, which is largely odor-free.

One per cent is hydrogen sulfide, generated by foods high in sulfur.

It can comes from the air we swallow or gas seeping into our intestines from the blood.

Flatulence becomes concerning to doctors if it is caused by a chemical reaction in the gut, or by bacteria in the gut.

What makes a fart smelly?

Smelly wind is generated when food is not processed properly - usually carbohydrates.

When carbs are not absorbed sufficiently into your intestines, particles sit in your gut and ferment.

"Foul smell just means the carbohydrates you consume are being malabsorbed - it's fermented," Dr Brand told Thrillist.

Why do some people have smellier farts?

"Some people are methane producers, and some people are hydrogen sulfide producers - which causes flatulence to smell like rotten egg," Dr Brand told Thrillist.

"It's all a function of what you eat."

What food makes farts smell worse?


Beer is carbonated, as are some wines. And both contain yeast.

A blog on the wine news site Vine Pair explained 'wine farts' are largely created by the hydrogen sulfide (H2S) generated in the brewing process.

It creates, a 'rotten egg, sewage like' smell when not properly ingested by the body.

This is the same for the yeast in beer - not helped by the bubbles.

Wine also contains mercaptans compounds, which have a 'rotten cabbage' smell.

Foods high in fructose, polyol, and sulfur

Doctors advise avoiding:

• Apple
• Pear
• Watermelon
• Cabbage
• Asparagus
• Leeks
• Onions
• Garlic
• Avocado
• Mushrooms 
• Cauliflower

Wheat and rye products

Doctors advise avoiding:

• Bread
• Pasta
• Noodles
• Cereal
• Cakes

Dairy products

Doctors advise avoiding:

• Milk
• Yogurt
• Ice cream
• Butter
• Cream
• Very milky or white chocolate


What should you eat instead?

These carbohydrates

For people with serious gastroenteritis-linked problems, Dr Brand would advise cutting out FODMAP carbohydrates from their diet.

FODMAP stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides And Polyols.

These carbs ferment and sit in the gut, conjuring smelly gas.

For most of us, a few FODMAPs should be ok.

Here are some alternatives:

• Rice
• Corn
• Potato
• Quinoa

High-protein diet

Protein does cause smelly farts. However, protein generates less gas, so you're likely to fart less, Dr Brand says.

For this option to work, it is crucial to avoid high-fat meats.

Instead opt for lean white meat, such as:

• Skinless chicken
• Turkey
• Fish
• Sirloin and tenderloin cuts of meat

What makes a fart loud?

That depends on the position of your sphincter.

If your sphincter is relaxed, the gas will pass without a sound.

Coffee, for example, naturally relaxes the sphincter, making people fart more as it is easier for gas to pass out.

When to consult your doctor

First, have a look at your lifestyle and diet if you think you fart too much (i.e.: more than 22 times a day).

For some people, gassiness could be a warning sign of a digestion problem - such as lactose intolerance or celiac disease.

It could also be a sign of a digestive tract infection or irritable bowel syndrome.

If you are concerned about your digestion and gas, visit a gastroenterologist for a consultation.

Daily Mail

Take your Radio, Podcasts and Music with you