The Border Breach and the Rise of SIBO

In my previous blog posts, we’ve looked at how your body produces a BLOCKBUSTER performance and delivers a digestive masterclass.

When the star of the show — Hydrochloric Acid (HCL) — nails its performance, the entire cast follows its lead...

• Your stomach’s defences stand tall... the gates are closed to unwanted intruders.

• Food is sanitised under the spotlight, ensuring only the good stuff makes it through.

• Acidic messengers signal the supporting acts into action: hormones, enzymes, and bile all take their marks.

Together, they set the stage for smooth digestion downstream...

That’s how it should work.

...But what happens when HCL isn’t doing its job?

When the stomach’s acid barrier weakens and those first lines of defence are left unmanned?

When food isn’t broken down effectively, and the signals to the pancreas and gallbladder become muffled?

That’s when an invasion can begin!

Act One: The Border Breach

A few months on, the scene looks very different...

• Your HCL levels have dropped.

• Defences are weakened.

• Food starts to linger... maybe even ferment.

• Transit time slows, pressure builds... your small intestine becomes VULNERABLE...

From the shadows, opportunistic microbes begin to advance.

They’re not foreign invaders...

(Easy, Nigel, we’re talking bacteria here.)

They’re locals from further down the intestinal tract, drawn upstream by the scent of undigested food.

In the large intestine, they’re harmless, mostly helpful. But here, in the small intestine, they’re trespassing.

At first, they explore quietly, testing the borders, slipping through weakened checkpoints.

Then, sensing little resistance, they begin to multiply.

What was once a clean, nutrient-absorbing corridor becomes a staging ground for overgrowth.

Each meal fuels their progress.

Carbohydrates become their energy supply; slow motility becomes their cover.

And with every bite, the population swells.

Act Two: The Perfect Conditions for an Invasion

Now the environment has shifted.

The small intestine, once protected, has become a paradise for microbes.

Low HCL means the acid “firewall” at the top of the gut is down, allowing more bacteria to survive the journey through the stomach.

Poor bile flow and sluggish enzyme release leave food half-digested, rich in fermentable sugars and fibres.

And with motility slowed, there’s no strong wave to clear debris or sweep the area clean.

The result?

A warm, nutrient-rich landscape with endless food and no resistance...

Microbial heaven!

As these populations expand, they begin to ferment what’s left behind, producing gas, heat, and pressure in a space that was never built for it.

Each gas — hydrogen, methane, or hydrogen sulphide — tells a different story about which faction is leading the charge.

The invasion is now in full swing!

Act Three: The Fermentation Factory

In a healthy system, fermentation happens further down ⬇ deep in the colon, the part of your gut purpose-built to handle gas, waste, and the occasional microbial rave.

But when that fermentation moves into the small intestine, it’s a different story.

It’s like running a brewery in your living room: heat, pressure, and fumes start building where they shouldn’t. It’s noisy, uncomfortable, and someone’s definitely going to complain... usually YOU!

The result is familiar to many:

• Bloating that builds as the day goes on

• Distension and discomfort

• Feeling full after just a few bites

This is...

Small Intestinal Bacterial Overgrowth (SIBO)!

Your microbial population is now booming in territory meant for digestion and absorption, NOT fermentation.

When this microbial uprising takes hold, your gut’s storyline takes a darker twist — energy dips, nutrients vanish, and inflammation simmers in the background like an unresolved subplot.

And just like any good movie, there’s more than one villain...

The Three Factions of SIBO

Hydrogen-dominant SIBO — The Fermenters

(aka quick and messy)

These bacteria thrive on carbohydrates.
When they feed, they release hydrogen gas, often leading to:

• Early bloating after meals

• Gurgling and flatulence

• Loose stools or diarrhoea

Hydrogen SIBO accelerates transit time so everything moves too quickly. Nutrients are lost, energy dips, and fatigue creeps in.

Methane-dominant (IMO) — The Occupiers

(aka slow and immovable)

Methane producers (technically archaea, not bacteria) consume hydrogen and release methane gas.

Methane slows motility, acting like a traffic jam throughout the intestines and leading to:

• Constipation or incomplete evacuation

• Bloating that lasts all day

• Weight gain or stubborn belly fat

Methane overgrowth often lingers — these microbes are hard to shift and thrive in sluggish, low-acid environments.

Hydrogen Sulphide SIBO — The Saboteurs

(aka silent but deadly)

These species use hydrogen but produce hydrogen sulphide gas which, unfortunately, smells the same as rotten eggs...

(I know... it’s not my favourite either.)

• Sulphur-smelling “eggy” gas

• Brain fog or fatigue after eating

• Burning or sensitivity in the gut

• Diarrhoea alternating with constipation (both... yay!!)

Hydrogen sulphide is toxic in excess and it irritates the gut lining, depletes energy, and contributes to systemic symptoms beyond digestion.

Act Four: When to Send an SOS

When this microbial invasion takes hold, your body lets you know.

• Bloating builds through the day, even after “healthy” meals.

• Gas, reflux, or discomfort creep in after eating.

• Energy dips, mood wavers, and food sensitivities start multiplying.

It’s not “just bloating” — it’s your body sounding the alarm — a sign that the wrong microbes have settled in the wrong place.

Act Five: Reinforcements Are on Their Way

To restore balance, you need a strategic approach — not a single supplement or guesswork diet.

Step 1 – Identify who’s invaded.
A SIBO breath test (measuring hydrogen, methane, and hydrogen sulphide) or comprehensive stool test clarifies what’s overgrown.

Step 2 – Starve and clear.
Short-term dietary adjustments and targeted antimicrobials or herbs may be needed to reduce the overgrowth.

Step 3 – Rebuild defences.
Support HCL, bile flow, and motility so food moves efficiently and bacteria can’t re-colonise.

Step 4 – Restore balance.
Reinoculate with beneficial microbes and repair the gut lining for long-term resilience.

When to Seek Support

If you’re experiencing persistent bloating, fatigue, food reactions, or that telltale “full after a few bites” feeling — it’s time to dig deeper. These aren’t random annoyances; they’re signals that your digestive defences may be compromised.

If you’d like to understand what’s really going on and take back control of your gut health, you can book a free Discovery Call to discuss testing, strategy, and how to rebuild your digestive system from the ground up.

Because when it comes to gut health... reinforcements are on their way!