How food affects the smell of your farts

When we eat a high-protein diet our gut bacteria produce seven times the rotten-egg smelling gas.

When we eat a high-protein diet our gut bacteria produce seven times the rotten-egg smelling gas.

Beans, beans the magical fruit, the more you eat, the more you toot - It's true that a diet high in fibre causes more flatulence, but at least it won't be stinky, promise researchers whose new study examined how different foods affect the gases in the gut.

Too much protein, on the other hand, and best of British to those who are within whiffing range.

The average person produces about one and a half litres of gas a day (producing an average of 10 to 20 farts), typically made up of the odourless hydrogen, carbon dioxide, methane, oxygen and nitrogen gases.

When we eat a high-protein diet, however, our gut bacteria produce seven times the rotten-egg smelling gas, hydrogen sulphide, according to a new study by Australian Monash University's Chu Yao.

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"This explains why bodybuilders who consume lots of protein powder are known to have smelly farts," Ms Yao told New Scientist of her research, presented at last week's annual scientific meeting of the Gastroenterological Society of Australia.

There's no need to eliminate eggs (or meat or dairy or other high-protein foods) from your diet though.

Ms Yao and her team found that slow releasing carbohydrates (in the form of resistant starch and fructans) reduced the hydrogen sulphide by about 75 per cent.

Why? They are highly fermentable, so move through the small intestine and are broken down by bacteria in the large intestine before the protein.

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"The focus is taken away from the protein, so hydrogen sulphide is not produced," Ms Yao explained.

They're better for our guts too, Trevor Lockett, head of the gut health and nutrition group at CSIRO Food and Nutritionhas said.

"Fermentable components of dietary fibre have a critical role in feeding the gut microbiome," said Dr Lockett.

"This part of fibre is fermented mostly to short chain fatty acids, a process which creates gas."

While farting generally indicates a healthy digestive system, excess can indicate digestive system disorders, such as irritable bowel syndrome.

When it is excessive, accompanied by chronic abdominal pain or changes in toilet habits, it is worth seeing your doctor.

In the meantime, if you want to gas the room, have your eggs on wholegrain toast, but don't bother apologising if your farts are stinky, because harmful as they smell, they may just be healthier than you think.


- Peppermint, ancient grains like spelt or amaranth, rye, ginger, fennel, pineapple and raw honey. Chewing properly also helps.

- Foods high in resistant starch

- Potatoes

- Bananas

- Legumes

- Cereals

- Foods high in fructans

- Wheat

- Artichokes

- Asparagus



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