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IBS Part 4: What is SIBO? Small Intestinal Bacterial Overgrowth

Have you heard of SIBO?

Small Intestinal Bacterial Overgrowth is often missed by doctors and is one of the biggest causes of IBS. Up to 80% of IBS cases may actually be caused by SIBO.

SIBO is when bacteria which is normally in the large intestine (where it should be!), migrates into the small intestine (where it should not be!). When this happens, the bacteria start to eat and ferment the food in the small intestine which can cause bloating, gas, cramps, constipation and diarrhoea.

Bacteria pass through a damaged ileocecal valve which connects the small and large intestine down at the bottom right of our abdomen. Usually this valve is closed but sometimes constipation, an infection, parasite, stress or food allergies, IBD, low stomach acid, cause it to malfunction and it stays open allowing bacteria to move through it.

Common Indications of SIBO

  • Bloating

  • Foul smelling gas (like methane or rotten eggs!)

  • Foul smelling stool

  • Reactions to vegetables such as onions, garlic, broccoli, avocado, stone fruits

  • Reactions to dairy, wheat, sweeteners, alcohol, honey

  • Constipation

Thankfully, a quick, easy and pain-free test can tell immediately - a breath test measures the concentration of hydrogen and methane in a person's breath. This gas is given off by the bad bacteria present in the small intestine.

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Is SIBO serious?

Not always, no - it's almost always manageable through nutrition, temporary diet changes and use of therapeutic herbs.

Some GPs may have heard of SIBO and treat it with antibiotics. I would always prefer to take a more natural approach using antimicrobial herbs instead as it keeps a much more harmonious balance of good bacteria in the gut (but always follow the advice of your GP).

Often SIBO is a common symptoms associated with IBD. This should always be tested for.

SIBO is often misdiagnosed and generally under-diagnosed, so it's just really important to get tested. Clinical symptoms might be non-specific (dyspepsia (indigestion), bloating, gas, abdominal discomfort, cramping). However, left untreated, SIBO can lead to serious complications including nutrient deficiencies, dehydration and malnutrition, and cause less serious symptoms such as bad breath.

Treatment is dietary changes and/or antibiotics. It's important to work with an experienced nutritionist or physician. Herbal antimicrobials are one route to treat bacterial overgrowth but in some cases antibiotics need to be prescribed along with a SIBO diet.

SIBO is linked to IBS as both conditions affect the entirety of the gastrointestinal tract. You may be doing all the right things in treating IBS, but if you're also not addressing issues further up in the small intestine, your IBS will continue to flare up.

I can test for SIBO in my clinic as well as put together a bespoke low FODMAP diet to rebalance the bacteria in the small intestine.

Here's what our client Kelly had to say about suffering with SIBO

"Having spent 10yrs with gut issues I connected with Kelly at Natural Balance. Kelly has some fantastic FREE content online, it was here I learnt about the condition i had been suffering from SIBO, Small Intestine Bacterial Overgrowth.

Kelly works in a very honest and open way, have me clear guidance and expectations on what it would take for me to get on a road of recovery to get my gut healthy again!

I was a little apprehensive of working with a Nutritionist but it was the best decision made. I worked with Kelly for nearly 8 months, now I have a much better idea of what foods trigger my gut discomfort and I also know how to remediate this myself naturally. I still contact Kelly if I have any questions and it’s great to know she’s there. While I have such a better understanding of my gut and body in general now. I believe this is just the start of my journey. Just like everything in life – you exercise to stay healthy, you see a therapist to help you mind, I will always see a nutritionist to help with my gut health. I couldn't recommend working Kelly at Natural Balance high enough."


Kelly Mulhall

Registered Nutritional Therapist


Kelly is a Registered Nutritional Therapist who focuses on positive physical and mental wellbeing, achieved through diet, lifestyle, sleep and exercise. Having struggled for years with IBS and hormonal imbalance, and increasingly frustrated with the lack of support and helpful advice from her GP, Kelly began her own journey of healing the body from the inside out. After seeing huge improvements she quit her job to study nutrition and focus on harnessing the healing powers of food to help other people in similar situations.

I am not attempting to prevent, treat or cure any physical, mental or emotional issues. Do not disregard medical advice or delay seeking medical advice because of information you have read on this website. Do not start or stop taking any medications without speaking to your primary health care provider.

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