Why Is SIBO Common Among Vegans? Insights From a Vegan Nutritionist

As a vegan nutritionist originating from the UK, I often get asked about SIBO — and whether a plant-based diet could be the culprit.

Let’s start with this: SIBO is not caused by plant-based diets.

However, certain characteristics of vegan eating can exacerbate or reveal an underlying SIBO — especially in someone with compromised gut motility or post-infectious changes in the microbiome.

Why SIBO Often Shows Up in Vegans

1. Higher Fibre and Prebiotic Load

Plant-based diets are rich in fermentable carbohydrates — fibres, resistant starches, and prebiotics that feed beneficial microbes. But if those microbes have migrated into the small intestine, this otherwise healthy fibre becomes fuel for fermentation in the wrong place.

2. Slower Transit Times

Some individuals have slower motility either naturally, or due to health conditions such as hypothyroidism, and diets very high in fibre can worsen this in the short term.

A sluggish migrating motor complex — the gut’s internal sweeping mechanism — is a core contributor to SIBO. Insufficient breaks between meals can be a big contributor to this.

3. Low Stomach Acid

Contrary to popular anti-acidity belief, stomach acid is essential for healthy digestion and acts as a first line of defence against bacterial invasion.

Some plant-eaters, especially those under stress or with nutrient deficiencies, may experience hypochlorhydria — low stomach acid — which is a known risk factor for SIBO.

4. Pre-existing Health Conditions

Many people switch to a plant-based diet from a poor current diet, or with pre-existing health conditions.

Their body may already be set up to be a perfect breeding ground for SIBO, and a sudden, dramatic increase in fibre simply exacerbates this.

It is also important to consider underlying factors such as chronic diseases, food intolerances, and addressing the root cause, as these can contribute to SIBO development and should be assessed as part of a comprehensive approach.

This Doesn’t Mean Plants Are the Problem

It’s tempting to blame the lentils or the broccoli — but this is a case of shooting the messenger.

A plant-based diet isn’t causing the issue — it’s just revealing an imbalance that may have been there all along.

Many people with SIBO report having had gut issues long before adopting a vegan lifestyle. In fact, many omnivores with SIBO struggle in similar ways, particularly if their diets are low in fibre, high in processed foods, or have a history of antibiotic use, alcohol overuse, or gut infections.

What we’re seeing isn’t a failure of a plant-based diet, but a body calling out for deeper support.

Healing SIBO on a Vegan Diet

SIBO can be addressed successfully while staying plant-based, particularly with the help of a qualified and experienced vegan healthcare practitioner.

A holistic strategy focuses on:

• Removing the overgrowth

• Repairing digestive function

• Restoring gut motility

This often includes:

• A vegan-friendly SIBO dietary protocol (short term only to reduce symptoms)

• Herbal antimicrobials — only if prescribed by a skilled practitioner

• Digestive support like bitters, enzymes, or nutrients to improve hydrochloric acid production

• Pro-motility agents, including ginger or certain probiotics under supervision

• Stress and nervous system regulation to support the gut-brain connection

Personalised guidance is essential, empowering clients to achieve control over their health by utilising knowledge, expertise, functional testing, and science as part of a holistic approach.

A skilled plant-based practitioner can guide you through this process without compromising your values or health goals.

A Final Word

As Hippocrates said, “All disease begins in the gut.” But so too does healing — often, with a return to simplicity, and a little trust in the body’s ability to restore itself.

SIBO can feel like a frustrating setback, especially when you’ve made admirable intentional choices for your health. But rather than viewing symptoms as failures, we can see them as messages.

The goal is not to abandon plants — but to support the body in digesting them more gracefully.

The journey toward wellbeing, wellness, optimal health, and a thriving life is supported by our mission to create a positive relationship with food, harness the incredible power and benefits of a whole food plant-based diet, and ensure all your nutritional needs are met.

With the right support, you don’t need to choose between your ethics and your gut health. You can have both.

🌱 Personalised Support from a Vegan Nutritionist (UK & Beyond)

I’m a vegan naturopath and nutritionist seeing patients online from the UK, Australia, New Zealand, Europe and beyond.

If you found this helpful, you may like my free resources created to support plant-based health:

📘 Download my guide “Why Many Vegans Fail—And How Not to Be One of Them”
🎥 Watch my webinar “Thriving on Plants” for practical tools and insights
💬 Book a 1:1 call to discuss your personalised plan tailored to your digestion, hormones, and energy