Why is my tummy so bloated?

You know that awful, bloated feeling when one minute your tummy is flat, and then the next you look six months pregnant and your jeans won’t do up? Maybe you’ve noticed your tummy balloons when triggered by eating certain foods, or perhaps it seems like everything sets you off these days? Is that expensive probiotic everyone raves about making you feel worse? Do those healthy, high-fibre foods cause total havoc on your tummy? And the gas… well, let’s just say it’s becoming a bit errr… embarrassing!

Here’s what most people don’t realise. Sometimes the problem isn’t actually what you’re eating, it’s an upper-fermenting gut problem. If the bacteria from your large intestine have inadvertently found their way into your small intestine (where they absolutely shouldn’t be), they start fermenting your food way too early in the process. This is called Small Intestinal Bacterial Overgrowth (SIBO), and it could be the missing piece of your bloating puzzle.

If your tummy starts to bloat and extend from the area just below your diaphragm and above your belly button (rather than the bloat starting at or below your tummy button), then read on to learn more about SIBO and what I have learnt from 30 years of clinical experience as a family naturopath.

What is SIBO and why do we develop it?

The small intestine is the long gastric tube that connects your stomach (which is positioned above the diaphragm) and your bowel (which is at the lower part of our abdomen). The small intestine is designed to efficiently digest and absorb the food we eat. It is also meant to be the area of our gut, which is (almost) devoid of bacteria, as bacteria present in the upper gut can inhibit these digestive processes.

There are two key mechanisms that help to prevent any meaningful levels of bacterial overgrowth in the small intestine. The first is optimal stomach acid secretion, which lowers our stomach pH, making the stomach a more acidic environment and inhibiting bacterial survival beyond this point in the digestive tract. The hydrochloric acid in the stomach is meant to zap any bad bacteria, preventing them from entering the small intestine.

Secondly, what is vital is efficient intestinal motility, which propels the food we eat (and any bacteria within that food) through the intestines and prevents the bacteria from lingering for too long in the small intestine. This ‘Migrating Motor Complex’ is your gut’s natural housekeeper, which through a series of rhythmic contractions from the stomach and small intestine sweeps along any undigested food, bacteria and other waste, preventing bacterial overgrowth and ensuring digestive cleanliness.

When these two protective processes are compromised due to stress, infection, inflammation, certain medications, or gastroparesis (slow stomach emptying) or even structural or nerve damage within the small intestine, then bacteria can accumulate and proliferate in the small intestine. This can then disrupt nutrient absorption and trigger symptoms such as bloating, gut pain, and altered bowel habits.

There are three primary types of SIBO: hydrogen-dominant, hydrogen sulfide-dominant, and methane-dominant. And which kind of SIBO you have very much depends on which bacterial strains have made their home in your small intestine. They often co-exist, and having two types of SIBO families can feel worse than double trouble. If you have two or three kinds of SIBO living in your intestines, you’ll likely feel quite unwell systemically, with a range of seemingly unrelated symptoms in addition to bloating.

Frustratingly, SIBO is usually the last test your gastroenterologist orders, even if you are severely bloated, because they are more likely to want to rule out more serious conditions such as polyps, tumours, coeliac disease, pancreatitis and inflammation first.

SIBO can also be linked to more systemic body and mind symptoms such as low mood, anxiety and energy crashes as well as itching and food intolerances and this is why it can be so pesky and problematic.

This blog shares with you the most essential things you need to know about SIBO and how to help clear this pesky bacteria from your upper gut through diet changes and targeted supplements.

Tell me more about SIBO symptoms

Gut symptoms

As you have learnt, Small Intestine Bacterial Overgrowth (SIBO) builds up when specific bacterial strains dominate the small intestine, interfering with food digestion. This typically causes symptoms such as bloating, gas, reflux, and nausea. Many people with SIBO get a feeling of fullness or loss of appetite and can experience weight loss or gain, abdominal pain or diarrhoea and very often people experience constipation. SIBO is now known to be one of the primary causes of Irritable Bowel Syndrome.

Links with chronic fatigue and mental health
SIBO is also increasingly known to be part of the picture in cases of chronic fatigue, post-viral syndromes, brain fog, anxiety and low mood. SIBO is strongly linked to depression and anxiety through the gut-brain axis, as the bacterial overgrowth causes inflammation, disrupts nutrient absorption (such as serotonin precursors), and also alters neurotransmitter production, leading to mood disturbances, brain fog and overall poor mental health.

Eating disorder links
Anorexia and bulimia have been associated with the onset of methane-dominant SIBO, which is likely due to a lack of potency of their hydrochloric acid in their stomach. People who have battled with eating disorders are often left with bloating, gas and constipation for months or even years afterwards. This is usually due to elevated levels of methane-producing bacteria and an imbalanced gut microbiome, which can build up and proliferate when the body is in starvation mode or during purging episodes. It usually does not resolve on its own, so it will need a helping hand from diet changes and supplements to help the tummy feel more comfortable and settled.

Histamine intolerance and SIBO
Histamine intolerance can show up as itching, sneezing, rashes, brain fog and fatigue. Many people with histamine intolerance see dramatic improvements when their underlying SIBO is addressed. Reducing the bacterial overgrowth typically allows you to tolerate a much wider range of foods without those frustrating reactions.

Based on our 30 years of clinical experience, this is likely because SIBO bacteria interfere with the gut’s ability to produce diamine oxidase (DAO), an enzyme that’s absolutely crucial for breaking down histamine.

When we don’t make enough DAO, we start reacting to ‘healthy’ foods like tomatoes, spinach and avocado, which are all naturally high in histamine. If you’ve found yourself suddenly unable to eat these foods which you used to love, then SIBO, which is disrupting your DAO production, could be the hidden culprit.

Pancreatic enzyme function and SIBO
If you still feel hungry after eating a meal, or you feel like the food you eat is not nourishing you properly, or you have undigested food in your stools, then you might not be producing enough pancreatic enzymes, which help to digest our food.

SIBO can also seriously compromise your pancreatic enzyme output, which shows up as low pancreatic elastase on testing and means you will have undigested food fermenting in your gut, and you will not be absorbing all the nutrients from the foods you eat. When bacteria linger where they shouldn’t be in your small intestine, they interfere with your ability to digest a wide range of carbohydrates, proteins and fats, and this can lead to a feeling of constant hunger and nutrient deficiencies.

So if you are the person who feels like you react to ‘everything you eat’, SIBO may well be at play. And the ripple effect can be significant – uncomfortable reactions after eating, that horrible post-meal fatigue, and systemic distress with a whole host of different symptoms throughout your body. Addressing SIBO often helps restore proper digestion and absorption and brings symptom relief across the board.

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How do I test for SIBO?

Breath Tests
This excess of bacteria in the small intestine can lead to the release of gases such as hydrogen and methane, which can be identified through a breath test. Some adult gastroenterologists currently offer this and these tests can also be ordered up via a qualified nutritional therapist, naturopath or functional medicine practitioner.

This test is non-invasive and can be done at home or under the guidance of a gastroenterologist. You need to fast overnight before carrying out this SIBO breath test. The test involves breathing into a tube, followed by drinking a specialist sweet drink (lactulose, glucose, or fructose), and then breathing into a series of other tubes at regular intervals, 2-3 hours after swallowing the drink.

This test is fairly straightforward for adults to do, and you need to set aside a morning to complete the test. However, some adults are so unwell or sensitive to the sweet drinks that this stalls them from carrying out a breath test. The breath tests are also harder for young children to do successfully, and a child needs to be quite compliant and mature to do it properly.

These breath tests can check for hydrogen and methane-dominant SIBO, but not hydrogen sulfide yet.

New Stool Tests
Thankfully, there is now a way around the breath tests, via stool testing, which involves collecting one small stool sample, which is sent off to a laboratory to be analysed.

Many stool test companies now look at a wide array of microbial markers that can indicate SIBO. These tests also have helpful markers related to inflammatory bowel disease, mucin degradation and gut barrier impairment, short-chain fatty acid production, as well as key markers for SIBO, H. pylori, dysbiosis and inflammation.

When you test all of these aspects of gut health at once it gives a full overview of the status of the gut as well as the likely SIBO strains that are lurking in your small and large intestines. From this information your practitioner has an informed way guiding you on reducing the levels of pesky SIBO bacteria and also help the gut to recover from the invasion so that ultimately you get your digestion back on track and a flatter tummy.

Mainstream gastroenterologists do not yet offer this stool-based SIBO strain detection method, but it is available through our NatureDoc clinical team.

Which markers to look for in a stool test?

The stool test markers that suggest SIBO is a likely issue for you may include Bilophila wadsworthia and Desulfovibrio spp., and to a lesser extent Fusobacterium, which all drive more of the hydrogen sulfide-dominant SIBO. Then Methanobrevibacter smithii, which is more methane-dominant, is also flagged in the stool tests. Hydrogen-dominant SIBO is still best diagnosed with a breath test.

Diarrhoea, dominant & rotten egg gas	Most Common Symptom	Predominant Gas on Breath Test	Markers on Stool Test
Hydrogen Dominant SIBO	General, not specific symptoms	Hydrogen H₂	–
Methane Dominant SIBO	Constipation dominant	Methane CH₄	Methanobrevibacter smithii
Hydrogen Sulfide SIBO	Diarrhoea dominant & rotten egg gas		Bilophila wadsworthia Desulfovibrio spp. Fusobacterium

Hydrogen Sulfide bacteria – diet & support

The hydrogen sulfide bacteria such as Bilophila wadsworthia enjoy a high-fat and high-bile environment and usually are more abundant in people with diets that are rich in saturated fats, especially dairy, meat and coconut oil. If you eat a more balanced diet with a wider range of vegetables, salads, pulses, nuts and seeds, then Bilophila wadsworthia should naturally be there in relatively low levels.

The hydrogen sulfate bacteria are more far-reaching in the body than just the gut and are linked with poor glucose control, as well as affecting circulation as well as heart health. However, even in the gut, these can lead to gut permeability, AKA “leaky gut”. A hallmark ‘rotten egg’ smelling gas has been associated with hydrogen sulfide-dominant SIBO.

When hydrogen Sulfide bacteria is dominant with high levels of bilophila, desulfovibrio and fusobacterium, then temporary relief can be made by short-term elimination (a few weeks only) of animal based proteins and high-sulphur plant based foods like alliums (onions, chives and garlic), cruciferous vegetables (cabbage, broccoli and cauliflower) and beans/pulses until herbal treatments have reduced the levels of hydrogen Sulfide bacteria. The four key foods for people with excess hydrogen Sulfide bacteria to avoid are garlic, onions, eggs and kale.

Hydrogen Sulfide bacteria also tend to respond well to herbal bitters such as Gentian, Oregon grape and Dandelion root. Antimicrobials may include Uva Ursi, Bismuth, Green Tea and Turmeric, as well as Zinc and Molybdenum.

Methane bacteria – diet & support

The world is currently concerned about how much methane our cows produce, but one of the key sources of methane is human bowel gas!

In SIBO, Methanobrevibacter smithii will more likely present in a constipation picture as it converts hydrogen into methane, which promotes a slow bowel transit. However, it can equally show up in excess amounts when a person is experiencing diarrhoea, bloating, pain and flatulence. So don’t rule this one out if you are not constipated.

Methanogens grow less in a low pH more acidic gut environment. Methanobrevibacter smithii on the plus side plays an important role in the digestion of polysaccharides (complex sugars) by consuming the end products of bacterial fermentation.

When Methanobrevibacter smithii is first identified through testing and there is more of a sluggish constipation picture, then my first port of call would be to add in flax seeds, chia seeds, hemp seeds, berries, nuts, brown rice, quinoa and green tea as well as kiwi fruit. Herbal blends like Ayurvedic triphala can also help, as well as specific kinetic herbal blends to help motility.

You can also use natural anti-microbial support such as herbs like Garlic (if Hydrogen Sulfide Bacteria are not present as well), Oregano, Uva Ursi and Neem as well as nano silver.

Prebiotics such as PHGG (Partially Hydrolysed Guar Gum) may be helpful in a methane-dominant SIBO picture and it has been found to improve the effectiveness of the antibiotic Rifaxamin which is sometimes used in SIBO treatment. PHGG is also excellent for populating the large intestine microbiome with a diverse population of friendly bacteria.

Table – herbal/prebiotic support for SIBO

Here are some research-backed herbal recommendations for the three main types of SIBO:

	Methane Dominant	Hydrogen & Hydrogen Sulfide Dominant	Both
Berberine		
Garlic	
Pomegranate Seeds, Juice & Skin		
Oregano			
Neem			
Clove		
Artemisia annua		
Old Man’s Beard (Usnia Lichen)		
PHGG	

Round up

SIBO can be tricky to shift, but with the right 1 to 1 support, nutritional guidance and a bit of patience, it is possible to have a flatter and more comfortable tummy. As well as less bloating, by clearing the SIBO you should also feel much more energised, and your mood should lift too. And, you should feel so much lighter and brighter all over!

Breath testing and stool testing can be invaluable tools for assessing if SIBO is the problem. Our NatureDoc clinical team can help you select the correct tests, and the results of these tests will help guide them to which herbal and nutritional supplements to recommend.

Why don’t you contact them today if you are really keen to work on your bloating and ongoing gut issues and get things sorted once and for all!

Ask me what supplements can help… or anything else!

NB. This is an update of a blog originally published 14th November 2021.

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