Could SIBO be driving your gut symptoms?

As a SIBO nutritionist I work with people who have an overgrowth of bacteria in their small intestine.

Anna mapson nutritional therapist Goodness me Nutrition

If you’re exhausted by researching SIBO, or trying to find a practitioner who actually understands it, I can help! 

For anyone new to SIBO, here’s a quick intro:

SIBO, or small intestine bacterial overgrowth, occurs when bacteria, which normally live in your large intestine, get into your small intestine. There they ferment food that we’ve eaten, and create gasses which affect our intestines. 

This can lead to symptoms such as bloating, diarrhoea and gas, but also all sorts of other symptoms like headaches, joint pain and skin conditions. 

You might have heard of SIBO whilst looking for solutions to for Irritable Bowel Syndrome. Small Intestinal Bacterial Overgrowth has only relatively recently been researched and discovered. Many doctors still even aren’t familiar with the symptoms or treatment.

There is a growing body of research papers that are investigating treatment and prevention using conventional and natural methods.

Why is SIBO a problem?

The large number of bacteria in the small intestine causes health problems because these microbes:

  • ferment starches and carbohydrates from your food in your small intestine, causing excess gas, bloating, diarrhoea or constipation.  For an overview of the difference in bloating caused by lactose intolerance and SIBO see my other article.
  • create a defensive structure called a biofilm around themselves. This helps to guard them because they are in the inhospitable environment of the small intestine, but makes it harder for us to treat.
  • can interfere with nutrient absorption, leading to nutrient insufficiency
  • may increase your sensitivity to food through reduction in the brush border enzymes.
flat lay with spinach, cucumber, pear, lemon and celery

How to know if you have SIBO

Some clues you might have SIBO include:

  • You feel worse when you eat prebiotic foods or supplements (inulin, beans, onions, garlic)
  • Sugar alcohols such as xylitol (often used in diet foods) makes your symptoms worse
  • Symptoms worsen with probiotic use, potentially because this may be adding to the overgrowth of bacteria
  • Fibre increases constipation symptoms
  • You feel better on antibiotics
  • You’ve had previous episodes of food poisoning that seemed to kick start your symptoms.
white woman's hands chopping a red cabbage on a light grey background

Risk factors for SIBO

There are three types of potential causes for SIBO

  1. Motility changes – this leads to impaired cleaning of the small intestine, resulting in more bacteria growing
  • Any reduction in the natural antibiotic nature of our digestive tract such as reduced stomach acid, or a reduction in the Migrating Motor Complex may lead to an overgrowth in microbes.
  • If you have a slow transit time there is more change the bacteria can start to cling to the walls of the small intestine. This means food is hanging out in the small intestine longer than it should, and bacteria get a chance to cling on and grow.


  1. Structural changes – slowing the passage of food through the gut through strictures, adhesions or scarring in and around the small intestines.
  • Anyone who has had a breach in the natural digestive defence systems is at risk of SIBO. This could be surgery such as appendectomy, laparoscopy, or C-Section because this may either bring in outside microbes, or cause scarring or adhesions which slow down the gut motility.


  1. Reduced natural defences – lack of proper defence such as impaired stomach acid production, bile acid flow, or reduced digestive enzymes.
  • Those who take medication to prevent stomach acid working are also at risk (e.g. Gaviscon, Omeprazole, sometimes called proton pump inhibitors (PPIs). As we age the stomach acid can also get weaker, which reduces the amount of protection it can give against incoming pathogens.

Read more about the risk factors for SIBO in this longer blog post.

How to diagnose SIBO

It’s important to rule out any other diagnoses so working with your GP to ensure they have completed any medical investigations they need to do. Most GPs won’t be familiar with SIBO, but a gastroenterologist may be able to test you. I can organise a  SIBO breath test as part of my 1:1 coaching work, but as these are paid for privately you may wish to ask your NHS doctor about a test as well.

To find out if you’ve got it, SIBO is diagnosed with a breath test. This helps to identify if you are creating too much hydrogen or methane in your intestines.

Treatment for SIBO

If you have a positive test there are several options for supporting SIBO. The best antibiotic for SIBO is Rifaxamin but this isn’t available on the NHS, only prescribed by private GPs in the UK. It’s well tolerated and has fewer side effects than other antibiotics.

  • Natural anti-microbials are also available in the form of herbs that work like oregano, berberine, grapefruit seeds.
  • A low FODMAP diet for a short amount of time may help because it will starve the bacteria in the small intestine. This reduction in microbe numbers can give you a break in symptoms, but it doesn’t treat SIBO. Read more about what to eat with SIBO in this blog post.  A low carb / FODMAP diet should reduce the symptoms like bloating and pain after eating, but it won’t necessarily get rid of the overgrowth of bacteria.
  • Digestive enzymes can support your body to break down food to make it easier to absorb the nutrients and prevent.
  • Sometimes if the anti-microbial supplements or antibiotics don’t work agents to break up the biofilms make help to weaken the microbes in the small intestine. 
  • Lifestyle changes are also recommended to ensure you’re getting enough sleep, and movement of your body
Recovering from SIBO
  • Probiotics (beneficial bacteria taken as a supplement) are not normally used in the early stages of SIBO, but as recovery takes place,
  • Other supplements to support gut healing can be useful to care for the lining of the small intestine after the microbes have been killed off.
  • Ideally you want to get back to eating as broad a diet as you can, with as much variety in fibre and nutrients. 

Contact me if you have digestive issues you want to address. I can help you find a SIBO diet that works for you and your body. Email me on info@goodnessme-nutrition.com.



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    Can you get rid of SIBO naturally?

    Herbal supplements can be used to treat SIBO, and in some cases they have shown promising results in comparison to antibiotics. Typical herbs to address the overgrowth of bacteria include oregano, neem, thyme, grapefruit seed extract, and berberine.

    When people ask about ‘natural treatments’ I like to clarify it depends what you mean by ‘naturally’! (Normally people mean without a doctor’s prescription.) Antibiotics such as Rifaximin definitely have their place in SIBO treatment and shouldn’t be automatically discounted.

    But I like to be very clear that the antimicrobial herbs you can use can also have a large impact on your gut microbes, and shouldn’t be taken long term or without supervision.

    Even with a combination of antibiotics and herbal treatments SIBO might require several rounds of treatment to reduce symptoms. SIBO can be very difficult to reduce.

    Depending on your levels of overgrowth, the type of bacteria you have, and your current diet and lifestyle, the alternative approach to ‘killing off’ bacteria is to encourage healthy beneficial bacteria to grow instead. This can be done through healthy lifestyle habits such as a good diet, changing your eating patterns, managing stress, improving sleep and focusing on encouraging diversity in your gut bacteria.

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    How do you get SIBO?

    There are multiple causes of small intestine bacterial overgrowth but significant risk factors include:

    • slow gut transit caused by poor diet
    • Previous stomach bug which could damage the migrating motor complex
    • adhesions or strictures slowing down the passage of food through your gut
    • frequent antibiotic usage
    • low stomach acid which can allow more microbes into the digestive system.

    You can read more about risk factors for SIBO here.

    Other conditions associated with SIBO include

    • low functioning thyroid / hypothyroidism
    • Fibromyalgia
    • EDS / hypermobility
    • Mast activation syndrome (MCAS)
    • histamine sensitivity
    • diabetes
    • Parkinson’s disease
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    How to test for SIBO

    Testing for SIBO is possible through a breath test that checks for hydrogen and methane gases. These gasses are made by the overgrowth of bacteria in your small intestine, and wouldn’t otherwise be there. The gasses are absorbed through the gut walls into the blood stream and exhaled in your breath.

    A stool test may be helpful in some cases to show which bacteria are in the large intestine although it’s not diagnostic for SIBO, because that’s the small intestine.

    I can arrange for a SIBO breath test, or a stool test to be carried out for you as part of the Gut Reset. I often wait until after our initial consultation to consider testing, because sometimes tests aren’t necessary. If you can make improvements to diet and lifestyle that improves your symptoms I don’t want you to pay for tests you don’t need.

    The symptoms of SIBO are similar to those of other gastrointestinal disorders such as irritable bowel syndrome (IBS), Inflammatory Bowel Disease and coeliac disease. This means it’s important to get your doctor to rule out other conditions.

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    Treatment for SIBO

    There are many options for improving the symptoms of SIBO, but the main element is understanding how you got the overgrowth of bacteria in the first place.

    Treatments to consider:

    1. Antibiotics are used to kill off the bacteria that has grown in the small intestine. The most common antibiotic that is used for SIBO is called rifaximin. Your gastroenterologist or GP may be able to help you get the right medication (as a nutritional therapist I can’t prescribe antibiotics).
    2. Another treatment option is herbal supplements such as antimicrobial herbs, prebiotics or Saccharomyces boulardii. There are various supplements for SIBO which can help to improve gut health and decrease bacterial overgrowth.
    3. Improving gut motility – through meal timing, food choices and supplements you can help your body with the internal housekeeper for the small intestine, the migrating motor complex. Read more about the migrating motor complex in my blog post.

    SIBO is a complex condition, which often requires more than one round of treatment. Also, it’s very important in SIBO treatment to use prokinetics to help keep the migrating motor complex moving.

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    What are the symptoms of SIBO?

    The symptoms of SIBO can vary from person to person and depend on where the infection is located in your intestines, how many microbes are there, and which kind of microbes. So it’s a very individual kind of condition, but common symptoms include:

    • Bloating
    • Diarrhoea
    • Gas
    • Nausea
    • Abdominal pain

    When you read that you might think these sound a lot like IBS, and you’d be right! There is a large overlap with people who have been told they have IBS, but actually may have SIBO. This is why it’s good to work with a nutritionist who understands SIBO.

    SIBO & IBS

    SIBO has a big overlap with the symptoms of IBS, it’s thought between 4% and 78% of patients with IBS have SIBO.

    There are different classifications of SIBO according to the different types of gasses produced by the microbes.

    Through their fermentation process microbes either create:

    • Hydrogen
    • Methane or
    • Hydrogen Sulphide

    Microbes which create methane and hydrogen sulphide rely on high levels of hydrogen to create their gasses.

    Symptoms are varied and can include excessive gas, bloating, distended tummy, reflux, constipation, diarrhoea, as well as non digestive symptoms like fatigue, skin rashes, or mood changes like anxiety or depression.

    Symptoms can also depend on the type of microbes and the gas they produce:

    • Symptoms of hydrogen predominant SIBO include diarrhoea (which may alternate with constipation), abdominal cramping, fibromyalgia.
    • Methane dominant SIBO presents with constipation, burping, nausea. An overgrowth of methane in the large intestine is called Intestinal Methanogen Overgrowth and is also linked to cooked cabbage smelling flatulence. I’ve written more detail on Intestinal methanogen overgrowth and constipation.
    • If you have hydrogen sulphide producing bacteria you’re more likely to experience foul smelling stools or gas, joint pain, bladder sensitivity and diarrhoea.

    There can also be issues with poor nutrient absorption leading to anaemia or loss of bone density. (I’ve written in more detail on how the bacterial overgrowth can reduce iron absorption.)

    SIBO seems to be more common in women, people over 50 and those with digestive issues.

How I can help you as a SIBO Nutritionist

I work with people who have IBS, SIBO, or unexplained bloating, constipation, gas or loose stools. As part of the Gut Reset I will 

  • Assess your digestive symptoms, but also look at mood, skin health, sleep, weight, muscle / joint pain and other relevant symptoms
  • Support you to find a diet that relieves the bloating, pains and gas
  • Arrange for SIBO testing at home and help you understand the results
  • Define a supplement plan for the 3 month Gut Reset programme and afterwards.
  • Help you implement the dietary changes with recipe ideas and meal plans, as well as understanding nutrition better so you can create your own meal plans.
  • Support you to eat a wider diet variety, reintroducing your eliminated foods again
  • Support you with regular calls so you really understand what to focus on each week.

Work with me - IBS & SIBO Nutritionist

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