The new science behind bowel habits, thiamine, and your gut’s “speed setting”

When your gut has a mind of its own

Bowel habits aren’t exactly anyone’s favorite conversation starter, but if you’ve ever planned your day around a bathroom, you know how much gut motility—how fast or slow things move through your intestines—can shape your life. Constipation, diarrhea, and irritable bowel syndrome (IBS) are common, frustrating, and often misunderstood.


A recent genetic study reported in Medical Xpress has highlighted an unexpected player in gut motility: vitamin B1, also known as thiamine. This doesn’t mean popping a supplement will “cure” constipation or IBS, but it does give us a new lens on how the gut is wired, and how nutrients and genetics may intersect in digestive health.

Restroom sign symbolizing bowel habits and gut motility
Everyday bowel habits reflect how quickly—or slowly—your gut is moving.

In this guide, we’ll unpack what this vitamin B1–gut motility connection really means, what we can say based on current evidence (as of January 2026), and how you can support your digestion in realistic, practical ways.


The problem: When gut motility speeds up or slows down

Gut motility is the coordinated movement of muscles in your digestive tract that pushes food along from mouth to rectum. When this process speeds up too much, you may get diarrhea. When it slows down, constipation can follow. With IBS, motility can be irregular—sometimes too fast, sometimes too slow—alongside pain and bloating.


These are not minor issues. Chronic constipation and diarrhea can:

  • Affect work, school, and social plans
  • Trigger anxiety about access to bathrooms
  • Cause pain, bloating, and fatigue
  • Lead to complications like hemorrhoids or nutrient malabsorption in severe cases


The new genetic study: A surprising vitamin B1 connection

The recent work summarized by Medical Xpress draws on large-scale genetic data to explore why some people naturally have faster or slower gut transit times. By looking at many common genetic variants across thousands of people, researchers can identify biological pathways that may influence bowel habits.


One of the unexpected findings was a set of genetic signals connecting gut motility to pathways involved in thiamine (vitamin B1) biology. In plain language, certain genetic variants associated with how fast your gut moves also intersected with how your body handles vitamin B1.

“These genetic associations don’t prove that taking vitamin B1 will fix bowel problems, but they point us toward nerve and energy pathways that could be important in how the gut moves.”

— Interpretation based on current gastroenterology and genetics research (2024–2026)

It’s important to stress: this is about genetic links and biological pathways, not a direct clinical trial of vitamin B1 supplements for constipation or IBS. The study adds a piece to the puzzle, rather than providing a quick fix.

Large genetic datasets are helping scientists uncover unexpected links between nutrients and gut function.

What is vitamin B1 (thiamine) and why might it matter for the gut?

Thiamine is a water-soluble B vitamin that plays a central role in how your cells convert food into energy. It’s especially important for the brain, heart, and nervous system. Since the gut has its own extensive nerve network—the “enteric nervous system”—it makes biological sense that thiamine-related pathways could influence gut motility.


Based on current evidence, thiamine:

  • Acts as a cofactor in enzymes involved in carbohydrate metabolism and energy production
  • Supports normal function of nerve cells, including those that control gut muscle contractions
  • Is absorbed in the small intestine via specific transporters that can be affected by genetics, disease, or surgery

Severe thiamine deficiency is rare in high‑income countries but can be seen in alcohol use disorder, certain malabsorption conditions, or very restrictive diets. In those rare cases, gut symptoms like nausea, poor appetite, or abdominal discomfort can appear—though they’re usually overshadowed by more serious neurological or cardiac issues.


What this research does—and doesn’t—mean for your digestion

When a new nutrient connection hits the headlines, it’s easy to jump to “Should I take this vitamin?” The reality is more nuanced.


What the current evidence supports

  1. Gut motility is partly genetic. Some of us are simply wired, from birth, to have faster or slower transit times.
  2. Vitamin-related pathways, including thiamine, may be involved in how gut nerves and muscles work. This fits with what we know about thiamine’s role in nerve and energy metabolism.
  3. Identifying these pathways could lead to new targets for future therapies—whether drugs, nutritional strategies, or both.

What the study does prove

  • That vitamin B1 supplements treat IBS, diarrhea, or constipation in the general population
  • That more thiamine is always better—very high doses can carry risks in specific medical situations
  • That you should stop any prescribed medications or treatments in favor of vitamins

Genetic discoveries are like signposts: they show us directions to explore, but they’re not the destination. Clinical trials are still needed before we can recommend vitamin B1 as a treatment for gut motility disorders.


A real‑world story: When “slow gut” meets realistic expectations

A patient I’ll call “Lena,” in her early 30s, had lived with constipation‑predominant IBS since college. She exercised, drank water, and ate plenty of fiber, yet still needed laxatives several times a week. When she read about the vitamin B1–gut connection in the news, she arrived at her gastroenterology visit with a bottle of thiamine tablets in hand and a lot of hope.


Together with her clinician, they reviewed:

  • Her diet—already rich in whole grains, beans, and nuts (all good thiamine sources)
  • Her lab work—no signs of B‑vitamin deficiency
  • Her medications and bowel pattern diary

Instead of relying on supplements alone, they focused on:

  1. Fine‑tuning her fiber type (more soluble fiber, slightly less insoluble)
  2. Scheduling “toilet time” after breakfast to take advantage of natural reflexes
  3. Adjusting her prescription gut‑motility medication
  4. Keeping a food and symptom log while maintaining an overall balanced diet, including natural thiamine sources

Over several months, Lena’s symptoms improved—not perfectly, but enough that she no longer feared travel days. The vitamin B1 news became a helpful discussion point about gut biology, rather than a single magic bullet.


Practical ways to support gut motility (without chasing miracle cures)

While the science on vitamin B1 and motility is still emerging, there are several evidence‑based steps you can take now to support your digestion. These won’t override genetics, but they can shift things meaningfully for many people.

A balanced, fiber‑rich diet with natural B‑vitamin sources remains a cornerstone of digestive health.

1. Build a gut‑friendly, thiamine‑aware plate

  • Emphasize whole foods: whole grains (oats, brown rice), legumes, nuts, seeds, vegetables, and fruits.
  • Include natural thiamine sources regularly, rather than relying solely on pills.
  • Adjust fiber gradually: aim for 20–30 g/day, increasing over 1–2 weeks to minimize gas and bloating.

2. Support your gut’s “body clock”

  • Try to eat meals at consistent times each day.
  • Set aside 10–15 minutes after breakfast for unhurried bathroom time.
  • Don’t ignore the urge to go—repeatedly delaying can dampen reflexes over time.

3. Move your body to move your bowels

  • Aim for at least 150 minutes of moderate activity per week (such as brisk walking).
  • Even short walks after meals can help stimulate motility.
  • If pain is a barrier, ask your clinician about gentle, low‑impact options.

4. Use supplements thoughtfully

  • Consider a standard multivitamin if your diet is limited, with your clinician’s input.
  • Targeted thiamine supplements may be appropriate for people at risk of deficiency (e.g., certain malabsorption conditions, very restricted diets, or alcohol use disorder), but dosing should be supervised.
  • Avoid high‑dose “megavitamin” regimens advertised as cures for IBS or constipation—these often lack solid evidence.

Common obstacles—and how to realistically work around them

Changing bowel habits isn’t just about biology; it’s also about real‑life constraints. Many people know what might help but still feel stuck. Here are some frequent barriers and practical workarounds.


“I can’t predict my bathroom access.”

  • Keep a small “travel kit” (wipes, spare underwear, discreet bag) to reduce anxiety on days your gut acts up.
  • Use symptom‑tracking apps or a simple notebook to notice patterns—certain foods or stressors may reliably affect you.

“My diet is limited by cost or culture.”

  • Lean on budget‑friendly sources: dried beans, lentils, bulk grains, and frozen vegetables are often rich in fiber and B vitamins.
  • Integrate gut‑friendly tweaks into your existing dishes rather than overhauling everything.

“I feel dismissed when I talk about my symptoms.”

  • Bring a short symptom summary to appointments: frequency, stool consistency, pain level, impact on life.
  • It’s appropriate to ask, “Could my nutrition, including B vitamins, be contributing to this—and do I need any blood tests?”
  • If possible, seek a clinician with experience in functional GI disorders or an IBS‑focused clinic.
Patient and healthcare professional discussing test results
A collaborative conversation with your clinician is still the cornerstone of managing chronic digestive symptoms.

For the curious: How genetics, nerves, and nutrients talk to each other

Gut motility is orchestrated by a complex network: smooth muscle layers, enteric nerves, immune cells, gut microbes, and hormones. Genetic studies—often called genome‑wide association studies (GWAS)—scan the DNA of thousands of people to spot variants that tend to travel with certain traits, like stool frequency or transit time.


When researchers see a “cluster” of variants near genes involved in thiamine transport or metabolism, it suggests:

  • People with certain versions of these genes may process thiamine differently in gut or nerve cells.
  • Energy production and nerve signaling in the gut wall could be subtly altered.
  • These changes might contribute, along with many other factors, to faster or slower motility.
Illustration on a laptop screen showing the human digestive tract and nerves
The gut’s own nervous system, energy pathways, and even vitamin handling all contribute to how quickly food moves through.

When to talk to a doctor about your bowel habits

While occasional constipation or loose stools happen to everyone, certain symptoms deserve timely medical attention.


  • Unintentional weight loss
  • Blood in the stool (red or black/tarry)
  • New‑onset constipation or diarrhea lasting more than a few weeks
  • Waking at night to pass stool frequently
  • Severe abdominal pain, fever, or vomiting
  • Family history of inflammatory bowel disease or colon cancer plus new bowel changes

Your clinician may recommend:

  • Blood tests (including nutrient levels, in appropriate cases)
  • Stool studies
  • Imaging or endoscopy, depending on your age and risk factors
  • Referral to a dietitian with experience in GI conditions

Bringing it together: Small, steady steps toward a calmer gut

The new research tying vitamin B1–related genes to gut motility is an encouraging reminder that our understanding of digestion is still evolving. It points toward nerve and energy pathways that may eventually guide better, more personalized treatments for constipation, diarrhea, and IBS.


At the same time, your day‑to‑day reality will likely be shaped less by a single vitamin and more by a combination of:

  • Consistent, gut‑friendly nutrition (including natural B‑vitamin sources)
  • Movement, hydration, and sleep
  • Thoughtful use of medications and, when appropriate, supplements
  • Open, ongoing communication with healthcare professionals

If your bowel habits are running your life, you deserve support. Consider this your invitation to:

  1. Track your symptoms for 1–2 weeks.
  2. Review your diet for simple, sustainable changes.
  3. Schedule a conversation with your clinician and ask specifically about motility, nutrition, and whether any testing—nutrient‑related or otherwise—is right for you.

You don’t need to solve everything at once. Even small, well‑informed steps can make living with a “sensitive gut” more manageable—and future research on links like vitamin B1 may offer additional options over time.


Further reading and trustworthy resources

For more in‑depth, evidence‑based information, consider: