SIBO (Small Intestinal Bacterial Overgrowth)

SIBO occurs in the small intestine as suggested and it can cause debilitating symptoms. When microorganisms from the large bowel find their way into the small intestine, due to a faulty ileocecal valve or other trauma to the bowel, such as a bout of gastroenteritis or surgery, they multiply quickly and become excessive in number. This can impact the health of the bowels and small intestine, compromising the integrity of the intestinal mucosa and causing slow motility


Two-thirds of patients experience uncomfortable symptoms such as abdominal pain, gas, extreme bloat or distended stomach, constipation or diarrhoea, nausea, heartburn, cramping, food sensitivities, skin symptoms (eg. eczema or rashes), respiratory symptoms (eg. asthma), mood symptoms (eg. depression and anxiety), joint pain and others. In extreme cases, weight loss, nutrient deficiencies and mucosal inflammation of the small intestine can also occur. Many people complain that their symptoms worsen as the day progresses, even after drinking water. People with SIBO may find it hard to digest and absorb nutrients, especially protein and carbohydrates, resulting in malabsorption. Further, damage to the gut barrier can increase immune activity due to inflammatory changes, which may worsen SIBO severity.

Causes of SIBO

  • Low stomach acid reduces the body’s ability to moderate bacterial growth. Factors that can reduce stomach acid levels are: prolonged use of certain medications, such as antacids and proton pump inhibitors, gastric bypass surgery and H Pylori bacterial infection.
  •  Food poisoning or gastroenteritis
  •  Endometriosis
  •  Dysmotility of the small intestine means that waste is retained for too long in the small intestine before emptying into the large bowel. Some dysmotility disorders include gastroparesis and hypothyroidism.
  •  Structural problems in the small intestine can inhibit motility and regular clearing of residual bacteria, as occurs in small bowel diverticulitis and abdominal adhesions, and a dysfunctional ileocecal valve.
  •  Overuse of certain medications, such as antibiotics, narcotics and gastric acid suppressants (reflux medications).
  •  Complications of abdominal surgery, including gastric bypass.
  •  Certain medical conditions, including Crohn’s disease, coeliac disease and diabetes can slow movement of wastes through the small intestine.
  •  Acid blockers
  •  Initial poor colonisation of gut bacteria due to caesarian birth and/or lack of breast feeding.

Impacts on health

Instead of allowing the villi in your small intestine to absorb nutrients from food, the bacteria digest it and cause it to ferment. A by-product of the bacteria’s digestion is methane and hydrogen gas, which is only produced by the bacteria and not our bodies. These gases cause bloating, flatulence, cramping, diarrhoea, belching, constipation and more. The presence of SIBO may also aggravate other disorders, such as IBS (irritable bowel syndrome) and IBD (inflammatory bowel disease), as well as chronic fatigue syndrome (CFS), acne, rosacea, leaky gut, fibromyalgia and restless leg syndrome. This is directly linked to the damaged villi being unable to absorb nutrients . Other drivers of this condition can include: 

  •  Chronic stress – this can cause a change in bowel habits, intestinal dysbiosis and low-grade gut inflammation, which can worsen SIBO severity.
  •  Toxin overload – alcohol and bacterial toxins can cause oxidative stress in the gut, resulting in widespread inflammation.
  •  Medication use – long term use of gastric acid suppressors can impact the mucosal lining.
  •  Ageing – elderly people can experience reduced gastric acid secretion as they age, which can increase their risk of developing SIBO.
  •  Certain gastrointestinal conditions – these can affect intestinal motility: diabetes, lupus, coeliac disease, IBS, scleroderma, cirrhosis of the liver, IBD, pancreatitis, colon cancer and chronic renal failure. 

Foods that may trigger SIBO

While foods are not usually the original cause of SIBO, certain foods can encourage the overgrowth of the wrong bacteria in the small intestine and exacerbate the symptoms of SIBO. These include:

  • Sugars and sweeteners
  •  Fruits and starchy vegetables, like potatoes
  •  Dairy products
  •  Grains 

The general recommendation for a treatment diet plan is a low carbohydrate diet, with the intention of starving the problematic bacteria of their favourite food. Foods containing fermentable fibre, starch, lactose and fructose can make SIBO symptoms worse. Foods such as gluten and grains, starches such as potatoes, legumes and pulses, fruits and some vegetables can be problematic. Although a high fibre diet is an optimal choice for good health, people with SIBO may feel their symptoms exacerbated by fibre. SIBO generates toxins, which puts pressure on the lymphatic system and our body’s own detoxification system. Unfortunately, SIBO goes largely undiagnosed which can result in years of damage to the small intestine. People may develop intolerances to certain foods like gluten, lactose or fructose, as the small intestine becomes less equipped to manage it. It can be difficult to treat other digestive problems if SIBO remains present, and the longer it remains in the small intestine, the more damage it can cause.


SIBO is diagnosed with a SIBO pathology breath test, which can be arranged for you if required by our experienced Adelaide naturopath. This simple, non-invasive test measures hydrogen and methane levels in your breath to determine the presence of gas-producing bacteria in your gut. If your levels are above a certain number, it suggests an abundance of bacteria. You may also need to undergo a stool test to rule out other infective agents. 


If left untreated or unmanaged, SIBO can cause more serious complications with long-term consequences. Malabsorption of fats, proteins and carbohydrates can lead to malnutrition and vitamin deficiencies. SIBO is treatable with the right diet, lifestyle changes and anti-bacterial herbal formulas. In addition, support may be required to encourage the growth and diversity of gut bacteria and to promote gut healing and improved motility.