SIBO (small intestinal bacterial overgrowth) is a relapsing and remitting condition that may affect up to 10-15% of the general population.
The hallmark of SIBO is that the small intestine becomes colonised with normal occurring gut flora. The small intestine is normally void of any bacterial colonisation but changes in the environment within the small bowel can lead to overgrowth of bacteria which can manifest with a collection of symptoms which signify SIBO, (1).
There can be many reasons for SIBO occurring, such as low stomach acid, pancreatic enzyme insufficiency, poor diet, stress and motility disorders, (4). Several studies have also demonstrated that abnormalities in the migrating motor complex (slow movement in the bowels) may predispose an individual to the development of SIBO, (2).
Individuals who are immunodeficient are also prone to bacterial overgrowth, (3). Certain diseases such as gastroparesis affect the nerves in the stomach, causing a slow down in the digestive process, (3). Coeliac disease also affects the small intestines, causing problems with absorption in the digestive tract. People with coeliac disease are at higher risk for SIBO. For these individuals, strict adherence to a gluten-free diet is essential for improving symptoms and overall health, (3), and deficiencies in certain nutrients may also make an individual more prone to SIBO. These include vitamin C, vitamin B12, vitamin D, vitamin E, calcium and magnesium, (3).
This can all cause problems with digestion, absorption of food and damage to the membranes in the lining of the small intestine leading. If SIBO is left untreated, it may lead to malnutrition and dehydration. It’s important to receive treatment to avoid these complications. Maintenance of remission is very important as SIBO is a relapsing disorder in several cases, (1).
Limiting fermentable carbohydrates and following a diet such as the low FODMAP diet may help the luminal environment that is exposed to low fermentable foods by decreasing a less favourable environment for any residual bacteria to overgrow. The movement and motility of the small bowel also needs to be optimised by the use of pro-kinetics which help to stimulate the MMC (migrating motor complex) of the small intestine to prevent recurrence and recolonisation of bacteria, (1). The goals of symptom relief are threefold: 1) correct the underlying cause; 2) provide nutritional support, if necessary; and 3) treat the overgrowth. This may include using antibiotics to regulate intestinal bacteria, addressing nutritional deficiencies and/or avoiding foods that cause symptoms, (3). With SIBO, lactose and fructose may be poorly absorbed due to inflammation along the lining of the small intestine. In addition to these two, other non-absorbed fibres may be fermented by the bacteria, leading to bloating and other digestive symptoms, (3). It’s often the gas that is produced by the unwanted bacteria that causes the bloating, abdominal pain, and diarrhoea (hydrogen SIBO), or constipation (methane SIBO), (4), and so symptoms should ease once the unwanted microbes are removed. Studies have also found that herbal remedies such as oregano oil, berberine extracts, and lemon balm may be as effective as standard SIBO treatment, (4).
It may also be advisable to remove or reduce dairy, wheat, bread, crackers, beans, lentils, artichokes, asparagus, onions, garlic and high sugar and dried fruits, (4). Instead, base your meals on foods such as eggs, meat, certain types of dairy such as brie, camembert, cheddar and feta, almond milk, grains such as rice, quinoa and oats, vegetables such as potatoes, cucumbers and courgettes and fruits such as grapes, oranges. strawberries, blueberries and pineapple, (4).
Typically, including a probiotic is also useful if well tolerated. Studies have shown that the use of a probiotic can be as effective as antibiotic treatment. And in addition, hydrolyzed guar gum may also be beneficial as a supplement, (4).
It could also be easy to mistake SIBO for other conditions, such as a lactose intolerance, which is also known to cause abdominal pain, flatulence, and loose bowel movements, (5). Those with a gluten sensitivity or celiac disease may benefit from a similar dietary protocol. One study has shown that it may be the FOS fibre in the wheat rather than the gluten that causes IBS symptoms, (5). But what are these fibres? Well, FODMAPS refer to a group of carbohydrates that are poorly absorbed in the small intestine and subsequently ferment in the small or large intestine. These may include fructose, lactose, fructans, galacto-oligosaccharides and polyols or sugar in alcohol. SIBO is a complex picture, and an entire lifestyle approach is needed when looking at the picture in terms of what may have brought about the symptoms and what can be done to ease them. Stress plays a big role in the picture, and so when working with a nutritionist, we will always look at all aspects of your life to help where possible with diet, lifestyle and supplement interventions to ease symptoms.
1 – https://www.gastrolondon.co.uk/management-of-small-intestinal-bacterial-overgrowth-sibo/
2 – https://www.healthline.com/health/sibo#complications
3 – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3099351/
4 – https://chriskresser.com/why-diet-alone-is-not-enough-to-treat-sibo/
5 – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4918736/