Today's Issue

Main Topic: The five most common causes of constipation, the biology behind each one, why most people only address one or two of them, and what actually moves the needle for each cause

Subtitles:

• Not enough fiber: the cause everyone knows, but most people get wrong

• Not enough water: why dehydration hardens your stool at the source

• Not moving your body: the gut-exercise connection that nobody talks about

• Stress and your gut brain: why anxiety literally slows your digestion down

• Medications and gut bacteria: the silent culprits that most people never suspect

Abstract: Constipation affects approximately 16% of adults globally, rising to 33% in adults over 60, and is defined clinically as fewer than three bowel movements per week, difficult stool passage, or a persistent feeling of incomplete emptying. Its causes are multifactorial. Dietary fiber, specifically insoluble fiber from whole grains and vegetables, adds physical bulk to stool and stimulates rhythmic muscle contractions (called peristalsis) in the colon; soluble fiber absorbs water and softens stool. Most adults consume 10–15g of fiber per day against a recommended 25–38g. Water is essential because the colon actively reabsorbs water from stool as it moves through; insufficient fluid intake causes stools to become dry and hard before they can be passed. Physical inactivity reduces the frequency and amplitude of colonic muscular contractions, slowing the speed at which waste moves through the gut (called transit time); even 20–30 minutes of daily walking has been shown to meaningfully improve bowel movement frequency. Chronic stress activates the hypothalamic-pituitary-adrenal (HPA) axis - the brain's stress response system - releasing cortisol, which disrupts normal gut muscle contractions and alters serotonin levels. Critically, approximately 90–95% of the body's serotonin is produced in the gut and acts as a key signal for triggering bowel movement; stress-related serotonin disruption is a primary mechanism of constipation.

Scale Your IRL Campaigns Like Digital Ads

Out Of Home advertising has long been effective but hard to scale—until now. AdQuick makes it simple to plan, deploy, and measure campaigns with the same efficiency and insight you expect from online marketing tools.

Marketers agree: OOH is powerful for brand growth, driving new customers, and reinforcing messaging. AdQuick makes it easy, intuitive, and data-driven—so you can treat real-world campaigns like any other digital channel.

Learn more, visit AdQuick.com

1. Not Enough Fiber: The Cause Everyone Knows, But Most People Get Wrong 🌾🔬

You've heard "eat more fiber" so many times it barely registers anymore.

But here's what most people don't know: not all fiber does the same thing, and getting this wrong is one of the main reasons fiber supplementation doesn't seem to work for some people.

There are two types.

Insoluble fiber - found in wheat bran, whole grains, and most vegetables - doesn't dissolve in water. It adds physical bulk to your stool and pushes against the walls of your colon, triggering the rhythmic squeezing contractions (called peristalsis) that move waste forward.

Soluble fiber - found in oats, legumes, and fruits - dissolves in water and forms a gel. It softens stool, making it easier to pass.

Most adults are getting 10–15g of fiber per day. The recommendation is 25–38g. That gap alone explains a lot.

One more thing: fiber needs water to work. If you dramatically increase fiber without increasing fluid intake, you can actually make constipation worse in the short term.

2. Not Enough Water: Why Dehydration Hardens Your Stool at the Source 💧🧱

This one sounds obvious. It's also more precise than most people realize.

As stool moves through your colon, your body is constantly absorbing water back out of it and into your bloodstream. This is normal and necessary.

The problem is: if you're even mildly dehydrated, your colon pulls out extra water to compensate.

The result is stool that becomes progressively harder, drier, and more difficult to move - not because something is broken, but because your body is doing exactly what it's supposed to do.

The effect compounds over time. Harder stool moves more slowly, which means it spends even longer in the colon, where even more water gets absorbed. By the time it needs to leave, it can be extremely hard to pass.

Daily fluid recommendations sit around 2–2.5 liters per day, but this number goes up with exercise, heat, caffeine (which is mildly diuretic), and high-fiber diets.

3. Not Moving Your Body: The Gut-Exercise Connection Nobody Talks About 🏃‍♀️⚙️

Your gut has its own nervous system - literally called the enteric nervous system - with more neurons than your spinal cord.

When you move your body, you activate this system.

Physical activity stimulates the rhythmic muscle contractions that push waste through your intestines. A sedentary lifestyle, on the other hand, reduces the frequency and strength of these contractions. Waste moves more slowly. Transit time (the time it takes food to travel from mouth to exit) gets longer.

Studies show that even 20–30 minutes of walking per day meaningfully improves bowel movement frequency. You don't need intense exercise. You need consistent movement.

The effect is most pronounced in people who go from sedentary to lightly active. If you spend most of your day sitting - at a desk, in a car, on a couch - this is likely contributing to your constipation more than you'd think.

4. Stress and Your Gut Brain: Why Anxiety Literally Slows Your Digestion Down 🧠😰

This one surprises people. But it's one of the most well-established causes in the research.

Here's the key fact most people don't know: about 90–95% of your body's serotonin is made in your gut, not your brain.

Serotonin in the gut is not about mood. Its job is to trigger the muscle contractions that move food and waste forward.

When you're chronically stressed, your body releases cortisol and activates what's called the HPA axis (your stress response system). This disrupts normal serotonin signaling in the gut, slows muscle contractions in the colon, and tightens the muscles of your pelvic floor - all of which make it harder to go.

A study using data from nearly 9,000 Americans found that anxiety significantly increased the odds of constipation. Nearly 60% of people in an American Gastroenterological Association survey reported that stress had a significant impact on their digestive symptoms.

The relationship goes both ways. Constipation worsens stress. Stress worsens constipation. It's a loop, not a one-way street.

5. Medications and Gut Bacteria: The Silent Culprits Most People Never Suspect 💊🦠

Two causes that often get missed entirely.

Medications first. Between 40 and 95% of people on long-term opioid painkillers develop constipation - because the gut has the exact same receptors as the brain, and opioids slow contractions there just as they slow everything else.

But opioids aren't the only problem.

Iron supplements, calcium carbonate (found in most antacids and many supplements), antihistamines, certain blood pressure medications, antidepressants, and diuretics (water pills, which cause dehydration) can all contribute.

If you started a new medication and your bowel habits changed within days or weeks, that connection is usually not a coincidence.

Gut bacteria second. People with chronic constipation consistently show lower levels of Bifidobacteria and Lactobacilli - the beneficial bacteria - and higher levels of Bacteroides compared to people with normal bowel habits.

These bacteria matter for three reasons: they produce short-chain fatty acids (SCFAs) that stimulate gut movement, they regulate serotonin production in the gut, and when certain bacteria produce methane gas, that gas directly slows down bowel contractions.

This is why probiotics - specifically strains like Lactobacillus rhamnosus and Bifidobacterium longum - have shown genuine benefits for constipation in clinical trials, beyond just being generally "good for gut health."

Takeaways

• Fiber (25–38g daily) and water (2–2.5L daily) are the two most fundamental causes to address first: insoluble fiber from grains and vegetables adds bulk that triggers colon contractions, soluble fiber from oats and legumes softens stool, and both require adequate hydration to work properly — increasing fiber without water can temporarily worsen constipation, while the colon's natural tendency to reabsorb water from stool means that even mild dehydration consistently produces harder, harder-to-pass stools.

• Physical movement stimulates your gut's own nervous system (the enteric nervous system, which has more neurons than your spinal cord) to produce stronger and more frequent colon contractions, while chronic stress does the opposite: it disrupts serotonin signaling in the gut (90–95% of the body's serotonin is made in the gut and triggers bowel movement), raises cortisol, tenses the pelvic floor, and creates a feedback loop where constipation worsens stress, and stress worsens constipation — even 20–30 minutes of daily walking has been clinically shown to improve bowel frequency.

• Many people never connect their constipation to a medication they've been taking for months, or to a shift in their gut bacteria: opioids cause constipation in up to 95% of long-term users, iron and calcium supplements are common overlooked culprits, and people with chronic constipation consistently show depleted levels of Bifidobacteria and Lactobacilli — the bacteria that produce the short-chain fatty acids and serotonin signals that keep the gut moving — making targeted probiotic support (Lactobacillus rhamnosus, Bifidobacterium longum) a legitimate evidence-backed intervention.

Build a LinkedIn Growth Routine That Actually Compounds

Taplio helps you grow followers with consistent posting, boost visibility with smart engagement, and iterate on what’s working with advanced analytics.

All in one place.

Try free for 7 days + $1 for your first month with code BEEHIIV1X1.

Try Taplio for free.