How well your gut moves affects your health and well-being, says Nick Aylott, a biotechnologist and bioinformatician from the University of Oxford.
What Did the Expert Report?
Once food is chewed and swallowed, it embarks on a long, winding journey through the gastrointestinal tract. Along the way, food encounters organs that digest it (the stomach), absorb nutrients (the small intestine), and extract water and salts (the large intestine).
The movement of food through the digestive tract is known as intestinal peristalsis. This process is partially controlled by trillions of bacteria. The gut microbiome is incredibly important, as it helps develop the immune system and break down food.
So, we’re not just feeding ourselves — we’re also nourishing the tiny helpers living in our intestines. In return, these bacteria produce small molecules called metabolites, which strengthen the immune system and stimulate the intestines to contract, pushing food further along.
Without bacteria and their metabolites, our intestines would be less capable of moving food through the gastrointestinal tract. This would lead to a buildup of swallowed material, which most people recognize as constipation.
Transit Time of Food Through the Intestines
This transit time varies among individuals. Recent estimates suggest that the passage of food can take anywhere from 12 to 73 hours, with an average time of about 23–24 hours, according to ScienceAlert.
Many factors influence how long food takes to move through the intestines, including genetics, diet, and the gut microbiome.
If intestinal peristalsis is slow, bacteria in the large intestine produce different metabolites. This happens because, like us, bacteria need nourishment. Typically, these bacteria prefer fiber. However, if the transit time through the intestines is too long, these microbial residents have to switch to an alternative food source, such as protein.
Switching to protein can lead to the production of toxic gases, resulting in issues like bloating and inflammation.
Slow transit can also cause partially digested food to get stuck in the small intestine. This situation raises the risk of excessive bacterial growth there and can cause abdominal pain, nausea, and bloating.
Accelerated transit through the intestines can also harm health. Causes of overly rapid transit include anxiety, inflammatory bowel disease, and irritable bowel syndrome. The harmful effects of fast transit include inadequate nutrient absorption and dehydration.
The Corn Test
Nick Aylott suggested a simple test to check intestinal motility. It’s called the “corn test,” and the steps are straightforward.
Avoid eating corn for 7–10 days (the “washout” phase). Record the date and time when you begin the experiment. Eat a small amount of corn (a handful is sufficient).
The outer shells of corn kernels are not digested. They travel through the entire gastrointestinal tract with other food and can be observed in the stool at the end. Note the date and time when this occurs.
If the shells appear in your stool within 12 hours, the intestines are moving rapidly. If they don’t appear within 48 hours, transit is slow. Generally, you can adjust transit time on your own.
If transit is slow but you don’t have concerning symptoms (bloating, abdominal pain, loss of appetite, or nausea), drink plenty of water and get regular physical activity. Eat more fruits and vegetables to increase fiber and nourish beneficial gut bacteria.
The key to good intestinal function is maintaining a balanced diet.
If food-transit issues happen regularly, consult a doctor.
Aylott says this home test produces results comparable to more complex research methods.
