Most people don’t often talk about their bowel habits, but how often we go to the bathroom can actually reveal a lot about how our digestive system is working.
When the gut doesn’t move things along properly, it can lead to problems like constipation, diarrhea, or irritable bowel syndrome (IBS).
These issues are common, but scientists still don’t fully understand what controls how fast or slow things move through the intestines.
A new international study offers fresh clues. Published on January 20 in the journal Gut, the study found new genetic evidence related to bowel movement frequency. Interestingly, it also found that vitamin B1—also called thiamine—might play a role in how often people go to the bathroom.
The research team was led by Professor Mauro D’Amato, a medical genetics expert at LUM University in Italy and CIC bioGUNE in Spain.
They looked at genetic data from 268,606 people of European and East Asian backgrounds and asked them about their bowel movement habits.
They used advanced computer tools to search for DNA patterns linked to how often people have bowel movements—what scientists call “stool frequency.”
The study discovered 21 regions of the human genome that are connected to how often people go to the bathroom. Ten of these had never been reported before. Many of these genetic regions matched parts of the body already known to affect gut movement.
For example, some were linked to bile acids, which help digest fat and send messages through the gut. Others were linked to nerve signals that control how the muscles in the intestines contract and push food along.
These findings were important because they confirmed what scientists already believed about how the gut works. But there was also a big surprise.
Two genes stood out—SLC35F3 and XPR1—because they are involved in how the body uses vitamin B1. This vitamin helps convert food into energy and supports the nervous system.
The researchers wanted to know if people who eat more vitamin B1 have more frequent bowel movements. They turned to another large dataset—the UK Biobank—which included diet information from nearly 100,000 people.
They found that people who consumed more vitamin B1 in their diet did tend to have more frequent bowel movements. But here’s the twist: this only seemed to be true for people who had certain versions of the SLC35F3 and XPR1 genes. In other words, your genes may affect how your body responds to vitamin B1 when it comes to gut function.
This suggests that vitamin B1 could influence digestion in different ways depending on your genetic makeup. It also opens the door to the idea that some people might benefit more from thiamine-rich foods or supplements than others—especially those with digestive problems.
The study also found a connection between these genetic patterns and IBS, a condition that affects millions of people around the world. IBS often involves problems with gut movement, such as going too often or not often enough.
The researchers believe that the genes and pathways they identified—including the vitamin B1 link—could help explain why some people are more likely to develop IBS.
Dr. Cristian Diaz-Muñoz, the lead author, said the research provides a “roadmap” of how the gut works and highlighted vitamin B1 as an unexpected but important piece of the puzzle.
Professor D’Amato added that these results are exciting because they point to very specific biological processes that can now be studied further. The next step will be to test how vitamin B1 affects digestion in lab studies and eventually in clinical trials.
This study is an important reminder that everyday body functions like bowel movements are influenced by both our diet and our genes. With more research, scientists hope to use this knowledge to create better treatments for people with digestive disorders.
If you care about nutrition, please read studies about the best time to take vitamins to prevent heart disease, and vitamin D supplements strongly reduce cancer death.
For more information about nutrition, please see recent studies about plant nutrient that could help reduce high blood pressure, and these antioxidants could help reduce dementia risk.
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