Many of us pay attention to the foods we’re putting in our bodies – asking ourselves whether they’re nutritious and healthy for us. But have you ever stopped to ask yourself how fast this food is moving through your gut?
The answer to this question is actually really important, as the speed that food moves through your digestive tract affects your health and wellbeing in many ways.
Once you’ve chewed up and swallowed your meal, this food begins its journey along the gastrointestinal tract – a long and winding pathway that begins at the mouth and ends at the anus.
Along the way, it reaches specialist organs that churn and digest (stomach), absorb nutrients (small intestine) and absorb water and salts (large intestine).
The movement of food through the digestive tract is known as gut motility. This process is partly controlled by the trillions of bacteria present in our gut. The gut microbiome is extremely important as these bacteria help develop our immune system and break down food.
So, when we eat, we’re not just feeding ourselves – we’re feeding the micro-helpers present in the intestine. To thank us, the bacteria produce small molecules called metabolites that boost our immune system and keep our gut moving by stimulating the intestinal nerves so they contract and move the food onwards.
Without these bacteria and their metabolites, our guts would be less able to move food through the gastrointestinal tract. This could cause a build up of ingested material, leading to constipation and discomfort.
Gut transit time
The time it takes for food to pass from one end of the gastrointestinal tract to the other is called gut transit time.
Gut transit time varies from one person to the next. Recent estimates suggest it can take somewhere between 12 and 73 hours for food to pass through the body – with the average being around 23-24 hours.
This variation in gut transit explains some of the gut microbiome differences seen between people – and consequently their gut health.
Many factors can also affect our natural gut transit time – including genetics, diet, and our gut microbiome.
If gut transit time is long (meaning you have slow gut motility), bacteria in the large intestine produce different metabolites. This is because, just like us, the bacteria in our guts need to be fed.
These bacteria enjoy fibre. But, if gut transit time is long and fibre is taking too long to reach the large intestine, these microbial inhabitants have to switch to an alternative food source. So, they turn to protein.
The switch to protein can result in the production of toxic gases leading to health problems such as bloating and inflammation.
Slow gut transit can also cause partially digested food to get stuck in the small intestine. This has additional health consequences – such as an overgrowth of small intestinal bacteria, which can lead to symptoms such as abdominal pain, nausea and bloating.
Fast gut transit can negatively impact health, too.
There are many reasons that someone may experience fast transit time. For example, anxiety, inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS) can all cause decreased transit time and even diarrhoea.
In cases of fast transit, the resulting stool is loose with high water content. This indicates that the faecal matter has not spent enough time in the intestine, preventing sufficient absorption of water and nutrients. In cases of IBD for example, this can lead to dehydration.
Testing your gut speed
Fortunately, there’s a very simple at-home test you can do to check your gut motility. It’s called “the sweetcorn test”. And yes, it is what you’re thinking.
Don’t eat any sweetcorn for 7-10 days (the “wash-out” phase). Then you are ready to begin the test. Note down the date and time, and eat some sweetcorn – a corn on the cob or a handful of corn is sufficient.
Because the outer shell of the corn is indigestible, it will pass through your gastrointestinal tract with the rest of the food you’ve eaten and will eventually be visible in your stool.
What you’ll do is keep an eye on the next few stools you pass and note down the date and time that you observe the golden treasure. It should be noted that this at-home test is not definitive – but it does represent a measure of transit time that, on average, gives similar results to more sophisticated measures.
If you pass the corn in 12 hours or less, your gut is fast. If you don’t pass it for around 48 hours or more, then your gut is slow. If you find your gut motility is on either end of the spectrum, there are fortunately things you can do to improve it.
If it’s consistently fast, it’s best to visit your doctor to see if there is an underlying cause.
If it’s a little slow – but you don’t seem to be having any additional gastrointestinal symptoms such as bloating, abdominal pain, lack of appetite or nausea – eat more fruit and veg to increase the fibre you’re feeding those friendly gut bacteria, drink more water and exercise.
Following a balanced diet will help to keep your bowels moving and healthy.
Nick Ilott, Senior Researcher and Lead Bioinformatician, The Oxford Centre for Microbiome Studies, University of Oxford
This article is republished from The Conversation under a Creative Commons license. Read the original article.
