Why is my Tummy so Bloated?

You know that awful bloated feeling – one minute your tummy is fine, the next you look six months pregnant, and your jeans won’t do up. Maybe you’ve noticed it happens with 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? 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 bacteria from your large intestine have 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 SIBO – Small Intestinal Bacterial Overgrowth – and it could be the missing piece of your bloating puzzle. Stick with me on this, because understanding this might change everything for you.

There are three primary types of SIBO: hydrogen-dominant, hydrogen sulfide-dominant, and methane-dominant. And which SIBO strains you have very much depend on what strains of bacteria have made their home in your small intestine. They often co-exist, and having two types can feel worse than double trouble. If you have two or three types living in your intestines, then you’ll likely feel systemically unwell with a whole host of seemingly unrelated symptoms.

SIBO is usually the last thing that your gastroenterologist will check you for, and sometimes it is the underlying trigger for more systemic symptoms such as low mood and anxiety, as well as bloating and an irritable bowel. 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 gut through diet and supplements.

Tell me more about SIBO symptoms

Gut symptoms

Small Intestine Bacterial Overgrowth (SIBO) occurs 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 methane-dominant SIBO. People who have battled with eating disorders often are 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 while the body is in starvation mode or during purging episodes. It does not resolve on its own, so it will need a healing hand to help the tummy feel more comfortable and settled.

Histamine intolerance and SIBO
Many people with histamine intolerance see dramatic improvements when 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 perfectly ‘healthy’ foods like tomatoes, spinach and avocado, which are all naturally high in histamine. If you’ve found yourself suddenly unable to eat foods you used to love, SIBO disrupting your DAO production could be the hidden culprit.

Pancreatic enzyme function and SIBO
SIBO can also seriously compromise your pancreatic enzyme output, which shows up as low pancreatic elastase on testing. When bacteria are lingering where they shouldn’t be in your small intestine, they interfere with your ability to digest a wide range of carbohydrates, proteins and fats.

If you feel like you react to ‘everything you eat’, SIBO may well be at play. And the ripple effect can be significant – 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 pancreatic function and brings relief across the board.

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 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 breathe 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 tests now look at a wide array of microbial markers, including 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. This way of testing is not offered through gastroenterologists or health insurance yet, but 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 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 right stool tests. Hydrogen-dominant SIBO is still best carried out by a breath test.

Types of SIBO	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 enjoy a high-fat and high-bile environment and are normally more abundant on diets that are rich in saturated fats, especially dairy, meat and coconut oil. If you eat a more balanced diet, then Bilophila wadsworthia should be really quite low.

The hydrogen sulfate bacteria are more far-reaching than the gut and are linked with poor glucose control, as well as affecting circulation and 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 key four 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.

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 and there is more of a sluggish constipation picture, add in flax seeds, chia seeds, hemp seeds, berries, nuts, brown rice, quinoa and green tea as well as kiwi fruit. Herbal blends like Triphala can also help as well as specific 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) maybe helpful in methane-dominant SIBO and it has been found to improve the effectiveness of the antibiotic Rifaxamin sometimes used in SIBO treatment and is also excellent for populating the large intestine microbiome.

Table – herbal/prebiotic support for 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 and nutritional guidance, 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. You should feel lighter and brighter all over.

Breath testing and stool testing can be invaluable tools for assessing if SIBO is the problem. Our NatureDoc practitioners can help you with selecting the correct tests and the results of these tests will help guide you and them with which herbal and nutritional supplements to recommend. Contact them today if you are really keen to work on your bloating and gut issues.

References

• Breath tests and irritable bowel syndrome
• Clinical importance of Bilophila wadsworthia
• A glycyl radical enzyme enables hydrogen sulfide production by the human intestinal bacterium Bilophila wadsworthia
• Microbial pathways in colonic sulfur metabolism and links with health and disease
• Implications of Hydrogen Sulfide in Glucose Regulation: How H2S Can Alter Glucose Homeostasis through Metabolic Hormones
• Intestinal Microbiome, Small Intestinal Bacterial Overgrowth and Inflammatory Bowel Diseases – What are the Connections?
• Irritable Bowel Syndrome, Particularly the Constipation-Predominant Form, Involves an Increase in Methanobrevibacter smithii, Which Is Associated with Higher Methane Production
• Methane positive small intestinal bacterial overgrowth in inflammatory bowel disease and irritable bowel syndrome: A systematic review and meta-analysis
• Clinical evidence of the role of Methanobrevibacter smithii in severe acute malnutrition
• Methanobrevibacter smithii is the predominant methanogen in patients with constipation-predominant IBS and methane on breath
• Small Intestinal Bacterial Overgrowth and Irritable Bowel Syndrome – An Update
• Methanogens, methane and gastrointestinal motility
• Methanobrevibacter attenuation via probiotic intervention reduces flatulence in adult human: A non-randomised paired-design clinical trial of efficacy
• Therapeutic Modulation of Gut Microbiota in Functional Bowel Disorders
• Herbal Therapy Is Equivalent to Rifaximin for the Treatment of Small Intestinal Bacterial Overgrowth
• Effects of essential oils on methane production and fermentation by, and abundance and diversity of, rumen microbial populations
• Effect of combined herbal feed additives on methane, total gas production and rumen fermentation
• Effects of Microbiota Imbalance in Anxiety and Eating Disorders: Probiotics as Novel Therapeutic Approaches
• Gut Dysbiosis in Patients with Anorexia Nervosa
• Gut Microbiome Changes in Anorexia Nervosa: A Comprehensive Review
• The intersect of gastrointestinal symptoms and malnutrition associated with anorexia nervosa and avoidant/restrictive food intake disorder: Functional or pathophysiologic?—A systematic review
• Identification of SIBO Subtypes along with Nutritional Status and Diet as Key Elements of SIBO Therapy
• Personality, Anxiety, and Stress in Patients with Small Intestine Bacterial Overgrowth Syndrome. The Polish Preliminary Study
• Association between small intestine bacterial overgrowth and psychiatric disorders
• Nutritional Approach to Small Intestinal Bacterial Overgrowth: A Narrative Review