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Farts and Good Gut Health

Those who enjoy a little "potty humor" will like the results of a recent nutrition study comparing the results of a Western style diet (high fat, low fiber) to a high fiber Mediterranean diet. The high fiber diet resulted in much larger, softer stools, and an increase in stomach noises and farting. (Yes, they weighed their stools and counted daily farts!) There was no change in the number of stools per day.

In the study 18 healthy men followed both types of diets for two week periods (first one diet, then a break, and then the other diet). The high fiber diet (54.2 grams fiber per day) resulted in numerous beneficial changes, especially nurturing healthy gut bacteria and metabolic improvements. The low fiber Western diet only had an intake of 4.7 g fiber per day. Interestingly, all participants were told to avoid fermented dairy products (e.g. yogurts) during the study.

The high fiber diet resulted in greater numbers of beneficial bacteria in the gut without any major changes in the core microbiome (microbial community). There were also numerous gut microbial metabolic improvements while on this diet. Interestingly, men who already had a more diverse gut microbiota (which is a sign of health) and routinely already ate more fiber rich plants foods, had less farting and stomach noises during the study.

Think of it this way: your diet is what feeds and nurtures the microbes living in your gut. Some microbes are associated with chronic diseases, and some with health - so you want to nurture the health-associated bacteria by eating a diet rich in plant foods (Mediterranean style diet).

By the way, a recent study found that eating fermented foods is a quick way to increase gut microbial diversity and health. It's beneficial to add some fermented foods (e.g. yogurt, kimchi, sauerkraut, kefir) to your regular diet.

From New Scientist: Men fart more when eating a plant-based diet due to good gut bacteria

Plant-based diets cause men to fart more and have larger stools, researchers have found – but that seems to be a good thing, because it means these foods are promoting healthy gut bacteria. 

Anecdotally, it is well-known that eating more plants – including fruit, vegetables, grains and legumes – creates bulkier stools and increases flatulence. However, few studies have measured these changes or related them to changes in gut bacteria.

Claudia Barber at the Liver and Digestive Diseases Networking Biomedical Research Centre in Barcelona, Spain, and her colleagues compared the effects of a Mediterranean-style diet mostly comprised of plants with a Western-style diet containing fewer fruit and vegetables on the guts of 18 healthy men aged between 18 and 38. Each participant was randomly assigned to follow one of the diets for two weeks, then after a break, they switched to the other diet for two weeks.

The men did a similar number of poos per day on the two diets, but each one was about double the size while they were on the plant diet. The men collected and weighed their own stools using digital scales and found they produced about 200 grams per day on the plant diet, compared with 100 grams on the Western diet.

This is because eating plants promotes certain types of bacteria in our guts that make food for themselves by fermenting plant fibre, says Rosemary Stanton at the University of New South Wales in Sydney, Australia. The added stool weight is made up of the spent bodies of these extra bacteria plus water and a small amount of undigested plant fibre, she says.

Some of the specific fiber-fermenting bacteria that became more abundant in the men’s guts while they were on the plant diet included Agathobaculumand anaerostipes and Agathobaculum butyriciproducens, an analysis of their waste showed.

The participants logged how many times they farted per day using a handheld counter and found they farted seven times more per day on average while on the plant diet than when they were on the Western diet. Each fart contained about 50 per cent more gas, as revealed when the researchers gave the men a test meal of stewed beans and measured subsequent gas production using balloons fitted to the men’s rectums.

Eating plants promotes farting because most fart gas is odourless hydrogen, methane and carbon dioxide that is produced by gut bacteria when they ferment plant fibre, says Stanton. The smell of farts comes from traces of hydrogen sulphide gas, which is a by-product of protein digestion.

Fiber-fermenting bacteria are known as “good” bacteria because they release short-chain fatty acids. These chemicals keep the large intestine healthy and protect against bowel cancer. Short-chain fatty acids can also be absorbed into the bloodstream where they protect against heart disease and diabetes by lowering cholesterol and regulating blood sugar.

The findings suggest that flatulence associated with eating more plants should be welcomed, says Stanton. “Our Western idea that farting is a sign of something being wrong is totally false,” she says. In most cases, “farting is a sign of a healthy diet and a healthy colon”, she says.

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