Predominantly inhabiting the large intestine, bacteria can also migrate to the small intestine, an area usually devoted to assimilating nutrients from liquified food, not a place suited to hosting bacterial overgrowths.  

Small Intestinal Bacterial Overgrowth, more commonly known by its acronym SIBO, is becoming more widely recognised and understood now that we have tests to identify the problem. An overgrowth of yeast is also a possibility, meaning it’s not strictly SIBO, but SIFO (fungal overgrowth), a common culprit being candida yeast.  

When these microbes move up too high into small intestine, this results in sensitivity, inflammation, reduced absorption of nutrients and offers a feeding ground for the bacteria, causing fermentation and gas production, resulting in bloating, flatulence, abdominal pain and diarrhoea.

As digestive symptoms can overlap wildly between digestive conditions, being able to differentiate between groups of symptoms is key when deciding on tests and nutrition protocols. If conditions such as inflammatory bowel disease and coeliac disease have been ruled out by a GP, delve into the specific symptoms.

Bloating and diarrhoea may be common to both IBS and SIBO, but gas production in the form of burping is more specific to SIBO. Feeling nauseous or a feeling of being constantly full and food not easily passing through can also be a sign of slow mobility, common in those with SIBO. (1) 

Fatigue may also be a side effect due to the lowered absorption of vitamins and minerals, especially iron and B12 which could lead to anaemia. Fat-soluble vitamins A, D, E and K may also be poorly absorbed. These deficiencies may present with dry skin, brittle hair and nails, dizziness and frequent colds. 

It is common to see inflammatory skin issues for individuals with SIBO, especially rosacea. (2) Other inflammatory skin issues, including acne and eczema, may also be exacerbated with increasing redness.  

Anyone can have SIBO, however certain groups of people are more likely to than others, especially those with gut motility issues (e.g. hypothyroidism, diverticulosis and diabetes) and existing bowel diseases which may affect the ability to break down food properly. SIBO is particularly prevalent in those with inflammatory bowel diseases (3), pancreatitis (4), hypothyroidism (5), and IBS. (6)

Also consider those who have experienced a bout of food poisoning or may have a history of frequent courses of antibiotics, resulting in vulnerability to bacterial infection. Individuals using Proton Pump Inhibitor medication (to reduce stomach acid production) may also be more likely to have SIBO. (7)  

If you suspect SIBO may be the issue, there is a simple test which measures the gas produced in the breath after consuming lactulose (in a fasted state). If high levels of methane and hydrogen are detected, this identifies an overgrowth of bacteria feeding on carbohydrates in the small intestine.

SIBO often coincides with other types of bacterial imbalances, yeast overgrowths or even parasites in the large intestine, so it may be worth doing a comprehensive digestive stool analysis to rule these out too. Don’t ever assume there is only one digestive issue to deal with.  

Before starting any nutritional protocol, it’s important to get a good overall understanding of your client’s medical history. The more you investigate, the more likely you are to understand the cause of their SIBO, which may help you to tweak their protocol to be personalised to that client. If someone has a history of regular use of antibiotics, for example, you may want to consider a high dose and broad-spectrum probiotic early on. Although antibiotic therapy is effective for SIBO, recurrence is high (8) so nutrition intervention is often needed for long-term elimination.

Whatever the cause, whether slow motility, insufficient ability to break down food or food sensitivities, there are a few aspects in common to all of these issues which can give the digestive system a break.

Firstly, and very simply, is to concentrate on digestion within the mouth. Telling people to ‘chew more’ doesn’t quite cut it when it comes to habit change; however, incorporating new environments and routines for eating can increase the likelihood of proper chewing. Meals should, ideally, be eaten at a table, from a plate, with the individual focusing on and appreciating the food. Eating on the go and multitasking while eating a meal are common causes for gulping down unchewed food, leaving big chunks for the stomach to deal with inadequately. 

Timing of eating and the size of meals can also affect the health of the digestive tract. Both binge-eating and snacking may be to blame. Over-eating can cause significant stress on the stomach and small intestine, with undigested food more likely to cause inflammation. Snacking too often also stimulates digestive juices, prolonging gut healing time. 3 main meals a day would be ideal, and up to 2 low-carbohydrate snacks a day would be fine, to reduce additional fermentation in the small intestine between meals. 

Where there is significant bloating and gas, and a long gastric emptying time (i.e. feeling over-full for more than 2 hours after eating a meal), then you may also want to consider a digestive enzyme supplement.  

‘Temporarily’ is the key word here. Digestive complaints and negative associations with foods can lead to very restrictive diets, and with dairy and gluten often cut out of the diet by this point, following a strict diet long term does not fix the root cause, but simply masks the body’s inability to cope with them for now.

A low FODMAP diet (low in fermentable carbohydrates such as cabbage, legumes, onion, dairy and some fruits) can be very effective at managing symptoms of bloating as you are limiting the food source for the bacteria, meaning less gas by-products are produced. Dietary FODMAPs induce prolonged hydrogen production in the intestine and influence the amount of methane produced. (12) A low FODMAP diet also significantly reduces histamine levels by 8-fold (13), which could explain improvements seen in inflammatory skin conditions. 

Following a low FODMAP diet for 2-4 weeks is a very effective tool for lowering fermentation for long enough to initiate gut healing. This can be done at the same time as taking the antimicrobial herbs, although it’s best to start after introducing new supplements, i.e. week 3. 

It is important to note that this diet is not a permanent fix as reducing FODMAPs only results in a temporary reduction in symptoms. As prebiotic foods in FODMAPs are very beneficial to the diversity of bacteria in the gut, a low FODMAP diet is not beneficial in the long term.  

When 2-4 weeks have passed on a low FODMAP diet, these individual foods can then be gradually reintroduced, ideally one food at a time. Keeping a ‘food and symptom diary’ would be useful at this stage to identify any foods which significantly worsen symptoms on reintroduction; they may then be excluded for a longer period of time.

Fermented foods such as kombucha, kimchi and sauerkraut should be introduced very slowly. These are highly beneficial in the long term but may cause symptoms of bloating in the short term if the SIBO has not been controlled to a healthy level.  

Once SIBO is confirmed by testing, the goal of the SIBO protocol is to ease stress on the digestive system, clear the bacterial overgrowth with antimicrobials, introduce healthy strains of bacteria, temporarily reduce aggravating foods such as FODMAPs, allow the gut lining to heal with the support of supplements such as l-glutamine, reduce inflammation with omega-3 EPA and gradually reintroduce FODMAPs with a nutrient-rich diet to replenish essential nutrients the body hasn’t been absorbing well. 

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