SIBO (Small Intestinal Bacterial Overgrowth)...

SIBO stands for small intestinal bacterial overgrowth and it occurs when abnormally high levels of bacteria are resident in the small intestine, where they don’t belong in large numbers. Normally, most of our gut bacteria live in the colon (large intestine), and the small intestine hosts relatively few. In SIBO, not only do bacteria overgrow in the small intestine, but the types of bacteria found there also resemble those typically found in the colon.

This bacterial imbalance can interfere with digestion and nutrient absorption, leading to a wide range of symptoms. It’s also increasingly recognised as a contributing factor in several chronic conditions such as irritable Bowel Syndrome (IBS), fibromyalgia, and chronic fatigue syndrome. In fact, it is thought that approximately 80% of those with IBS have SIBO.

What Causes SIBO?

The majority of microflora should be in the colon, but during digestion, some bacteria migrate into the small intestine. The body has a clever system for keeping bacteria in the right place. In a healthy digestive system, bacteria are kept in check by the migrating motor complex (MMC). This housekeeping mechanism involves a series of muscle contractions (peristalsis) that help to sweep residual bacteria and undigested food from the stomach and small intestine through the digestive tube and into the colon. This cycle is aided by secretions from the stomach, pancreas, and liver and starts approximately 90 minutes after food is consumed. The process can take up to roughly 3 hours to complete, but eating interrupts the process, including milk in a cup of tea or coffee.

When this cleaning wave is disrupted, whether by poor motility, food, low stomach acid, or other digestive dysfunctions, it creates an environment perfect for bacteria to overgrow.

Symptoms of SIBO

SIBO can present with a wide range of symptoms, many of which mimic other digestive disorders including:

• Bloating, burping, and gas—especially after meals

• Abdominal pain or cramping

• Diarrhoea or constipation (or alternating between both)

• Fatty or floating stools

• Lactose intolerance

• B12 or iron deficiency anaemia

• Reflux, heartburn, or nausea

• Brain fog, memory issues, and headaches

• Joint pain

• Food sensitivities

If you’ve been diagnosed with IBS or have ongoing digestive issues that haven’t resolved with conventional treatments, or if your symptoms reduce when you are taking antibiotics, or are exacerbated when eating probiotic foods, SIBO may be worth exploring.

Testing for SIBO

The most common method for testing SIBO is through a breath test, which measures the levels of hydrogen and methane gases exhaled after drinking a mixture of glucose and water. A rapid rise in exhaled hydrogen or methane may indicate bacterial overgrowth in your small intestine.

Other tests, such as a stool analysis, may be suggested to check aspects of digestive function that might be causing or contributing to your symptoms, such as pancreatic function or poor fat absorption. Stool analysis can also identify the presence of specific microflora which are known methane or hydrogen sulphide producers; their presence may lead to further recommendations to test for SIBO.

Factors that can increase the risk of developing SIBO:

• Low stomach acid – Inadequate stomach acid leads to poorly digested food in the small intestine, which acts as a food source for bacteria, allowing them to overgrow. Long-term use of proton pump inhibitors such as omeprazole is therefore a risk factor as these reduce the acidity of the stomach acid.

• Pancreatic insufficiency – Reduced enzyme production leads to poorly digested food, which feeds bacteria.

• Stress – The digestive process, including secretion of digestive juices and motility, is controlled by the parasympathetic nervous system. Stress shuts down this part of the nervous system, impairing digestion and compromising the action of the MMC.

• Damage or scar tissue in the digestive tract - Structural changes from surgeries, coeliac disease, radiation damage, diverticular disease, adhesions, obstruction, or scleroderma can compromise the regulation of digestive juice secretion and the function of the MMC.

• Hypothyroidism – Low thyroid function can reduce the activity within the gastrointestinal tract, slowing the migrating motor complex. It can also impact bile flow. Bile is a natural antimicrobial which helps to limit bacterial overgrowth in the small intestine, when bile flow is compromised, bacterial colonisation may occur there.

• Diabetes – High blood sugar can damage nerves that control the MMC.

• Weakened immunity –Various immunodeficiency syndromes have been associated with increased risk for bacterial overgrowth, including IgA deficiency. Secretory IgA in the gastrointestinal tract helps prevent bacterial proliferation. It can be negatively affected by stress, gut infections, long term toxin exposure and food reactions.

• Infections – Viruses such as Epstein-Barr or Lyme disease have been linked to poor gut motility.

• Hormonal imbalances – Oestrogen can inhibit the production and excretion of bile. Reduced bile flow can be a predisposing factor for SIBO. Oestrogen also delays gastric emptying and motility.

• Ageing – Older adults are more likely to have low stomach acid and impaired motility, making SIBO more common with age.

Conventional Treatment & Holistic Support

Conventional treatment of SIBO typically involves antibiotics, and while many people experience relief after taking them, symptoms often recur if the underlying root cause hasn’t been addressed.

Numerous herbs also exhibit antimicrobial actions and can support SIBO eradication. However, they should always be used under the supervision of a qualified Medical Herbalist.

Nutritional therapy looks at resolving the underlying drivers contributing to the development of SIBO and several SIBO-specific diets can also help reduce symptoms. It’s worth noting that some probiotic and fibre supplements can worsen symptoms in people with SIBO because certain bacteria ferment fibre into gas, which exacerbates bloating and discomfort.

If musculoskeletal imbalances are driving digestive symptoms and impacting the MMC then Osteopathy can add another string to the bow when supporting SIBO. Likewise if your nervous system is contributing to the symptoms Cranio-Sacral therapy can also offer support.

SIBO Lifestyle Tips

Lifestyle changes can play a big role in preventing SIBO relapses and promoting long-term gut health:

• Eat mindfully: take your time to eat, engage fully with your meal and chew everything really well to help maximise digestive secretions and motility

• Only eat when calm: The parasympathetic nervous system aka the “rest and digest” arm needs to be activated for digestion to function optimally. Eating in a stressed state impairs motility and enzyme production.

• Stimulate your vagus nerve daily: Add a daily practice to your routine which supports activation of the parasympathetic nervous system. Choose something that makes your digestive system gently gurgle! This is a good sign that you’ve switched on your rest and digest functions. Breathwork, meditation, yin yoga, using a shakti mat and guided visualisations can all help.

• Space your meals: Try to allow at least 4 hours between meals to let the MMC run its course. Constant snacking can interrupt this natural cleansing wave.

SIBO is a complex condition that can significantly affect your wellbeing, but with a personalised, multidisciplinary approach, symptoms can be resolved.

If you're experiencing persistent digestive symptoms, fatigue, or food intolerances, don’t hesitate to speak with our clinic team. We're here to support your gut health journey from all angles from nutritional therapy, to herbal medicine, osteopathy, and beyond.

By Holly Rothschild (Registered Nutritional Therapist)