Understanding Small Intestinal Bacterial Overgrowth (SIBO) – Part 1
Understanding Small Intestinal Bacterial Overgrowth (SIBO) – Part 1
About the author : victoriafenton
I am fairly used to clients arriving in my clinic having been dismissed by the medical professionals with whom they have consulted thus far. Most recently, I have seen an alarming number of people seeking me out complaining of incredibly distressing digestive symptoms, having been sent away by their GP with a diagnosis of Irritable Bowel Syndrome (IBS). In almost all of these clients in the last few weeks I have found SIBO to be an underlying factor in their issues. So why is this going undiagnosed or misdiagnosed by conventional medicine?
What Might Be SIBO?
Roughly 60% of IBS cases have been shown to be linked to Small Intestinal Bacterial Overgrowth (SIBO). When you consider that IBS occurs in 25% of the UK population – and actually approximately 25% of the global population – this is a large majority of adults. When you consider that IBS is not always diagnosed, and many adults in the western world battle through digestive symptoms without seeking help, it could be considered that SIBO is a drastically underappreciated condition which affects the health, wellbeing and quality of life for the global adult population. If you’ve been to the doctor with the following symptoms, your doctor may have diagnosed you with Irritable Bowel Syndrome:
Bloating, distension, swollen belly
Diarrhoea and/or constipation – sometimes both
The sensation that food is stuck in the stomach
Food intolerances seeming to give GI symptoms
Food intolerances seeming to give rise to systemic issues
Fatigue, anxiety, brain fog (linked to the systemic issues mentioned above)
IBS is a catch-all term which covers some, or all, of the above. And it is deplorably unscientific and un-useful. It is just a description of a host of digestive disturbances and carries with it very little clinical utility. I have seen many, many patients who have been sent away from their GP with a prescription for a ‘remedy’ for whatever digestive complaint has been most prominent in their presentation: proton pump inhibitors (PPIs) for those with reflux, laxatives for the constipated, antiemetics for the nauseous and even Mebeverine (a motility agent) for those who seem to not digest food well. Or worse, and commonly, patients are dismissed with the assertion that “we know there is a stress component to IBS” (actually true but still unhelpful) so there is an erroneous accusation that it is ‘all in their head’ – and so they are prescribed an antidepressant. It is true that GI symptoms are highly correlated with anxiety and stress, you only need to read my work on Autoimmunity and Psychology to know that I believe this to be fundamental. However, it is naive to discount the fact that mood changes go hand in hand with gut issues, for a whole host of reasons, not least of which the presence of constant pain can be depressing and cause great anxiety. If you have read anything I have posted you will know that the relationship between gut and brain has been shown to be bi-directional. I.e. Our mood, anxiety and stress levels can affect digestive wellbeing, but these levels themselves are also directly affected by tension and irritation within the digestive tract. In the case of SIBO – which is an actual diagnosis, rather than a term which describes a collection of symptoms such as “IBS” – it is clinically proven that psychological and emotional issues, along with excessive anxiety, can be drastically improved by treating the pain and digestive symptoms affecting patients with excessive GI complaints.
Ruling Out Parasites and Bad Bacteria
Many people are now aware of the concept of the microbiome. In the light of digestive disturbance, many patients seek out a stool test from one of the Functional Medicine labs like Genova or Doctors’ Data. When these come back showing no pathogenic bacteria, patients could be forgiven for thinking that their GP was right – it’s just IBS. And yet there is a large cohort of patients who have been told by their GPs they have IBS AND who have then ruled out parasites and infections who may actually be suffering with SIBO. If you’re struggling to get to the bottom of things, it could easily be the case that SIBO is part of your clinical presentation.
Anatomy of a Hidden GI Issue
The small intestine takes up a remarkable amount of your gastrointestinal tract – it is the wiggly bit that starts beneath the stomach and winds around for a good, long distance prior to meeting the large intestine at the Ileocaecal valve. The small intestine itself has three sections or parts, and should ideally be a fairly acidic environment, with a good degree of flow through it. It is the main location from which nutrients are absorbed from the food we ingest. Small Intestinal Bacterial Overgrowth occurs when there is a bacterial accumulation in the small intestine of “normal” flora, which is just commensal bacteria (i.e. they’re not pathogenic and they’re supposed to be in our body) which has translocated into the place. Bacteria should NOT be in our small intestine for any length of time. It must be made clear that bacteria are supposed to enter our Small Intestine. They are, however, supposed to move through and swiftly leave. The problem occurs when the process of movement through the small intestine and flow into the large intestine is impaired. Instead of a consistent downward trajectory being maintained, perfectly healthy and normal bacteria proliferate in a place where they should not be. Symptoms like those on the list above are the result.
So Why Isn’t the Small Intestine Clearing Its Bugs?
Risk factors for SIBO form a long list. From genetics to surgery, antibiotics to stress, HCL levels to dietary choices and many, many more. Additionally, issues with immunity and autoimmunity can affect the flow of the small intestine, along with thyroid function, hormone levels, vagus nerve enervation issues as well as heritable conditions of collagen disorders. This is where I really geek out on the science of this – for professional and personal reasons. For those who aren’t aware, my own trajectory into healthcare arose out of the chronic and life-altering implications of a genetic connective tissue disorder, Ehlers Danlos Syndrome, combined with neurological complications, POTS and vagus nerve issues, alongside dramatic digestive disturbances. This is actually quite a common grouping of issues, but healing my intestines became vital for my survival on several separate occasions. This is why gut health is so dear to my heart. Yet, beyond my complications, our digestive system is complex – and it can go wrong, for many, many reasons. A common cause of inhibition in this flow-process is a deficiency of stomach acid, or hypochlorhydria, which is actually remarkably common. This means that the bacteria (in the air, food and in every part of everyday life) aren’t killed in the mouth/stomach and so enter into the small intestine in larger amounts than normal. Acid reflux can be due to LOW stomach acid and occur with SIBO – so you can see how here, where a GP might offer a dismissive prescription for a PPI (designed to minimise stomach acid), they are actually doing more harm than good. When a lack of stomach acid may have contributed to the bacterial proliferation in the first place, lowering acid levels still further is a recipe for disaster. However, not everyone with low stomach acid gets SIBO. So what else is forming the development of this pathology?
The Migrating Motor Complex – the Caretaker of the GI Tract
The small intestine is built in such a way to move bacteria through and out into the large intestine where bacteria are supposed to feed off the remaining substrate in our diet. The Migrating Motor Complex (MMC) is the physical function that is there to facilitate this process and ensure continuous downward motion of food through the digestive system. This is not the peristalsis that we think of as the ‘squeezing’ of the gastrointestinal tube which is responsible for moving food down our oesophagus after a meal, and for our bowel movements. Instead, the action of the MMC occurs when we are NOT eating (or after around 90 minutes with no food). The function of this MMC is a sort of ‘house cleanse’ process, like a brushing of all of the bacteria through the small intestine and into the large intestine. The command to do this is given through the parasympathetic nervous system to cells in the small intestine (on which more later). If the MMC breaks for any reason, flow is interrupted and bacteria hang around too long – SIBO is the result. The anatomy of the small intestine is important for effective MMC motions. Many life circumstances can give rise to adhesions and abnormal alignment of the small intestine tubes, such as operations, accidents or diverticula issues. Appendicitis can cause obstructions and adhesions, as can endometriosis and other fallopian tube or womb issues such as fibroids and, perhaps obviously, in Inflammatory Bowel Disease the bowel abnormalities might influence the structure of the small intestine and therefore affect the bowel transit. If structural issues affect the alignment of the small intestine, it may seem obvious that the MMC gets interrupted in its actions.
But there are other issues which can give rise to GI tract issues which affect MMC and SIBO.
Breaking the Migrating Motor Complex
As mentioned above, the MMC is driven by cells which are connected both to gut tissue and to the parasympathetic nervous system. These cells are called the Interstitial Cells of Cajal (ICC). Whilst you don’t need to remember this, it is important to understand that without effective functioning of these Cells of Cajal, the MMC cannot fully function. The natural result is slowed MMC and bacterial proliferation.
The reasons why the ICC may become dysfunctional are still being discovered. However, there are some interesting proven mechanisms, the most common of which being Food Poisoning (or travellers’ diarrhoea from bacterial infections from food etc.)
Very simply, the bacteria responsible for this sickness produce toxins which are very similar (from an immune perspective, at least) to the Interstitial Cells of Cajal. If our immune system is primed to attack the bacteria and toxins in traveller’s sickness, it can also develop an immune sensitivity to the ICC. If a significant portion of our ICC are eliminated, the MMC is disrupted and slowed which prevents the quick, smooth flow of bacteria into the large intestine.
There are also other factors which can influence all of this – such as hypothyroidism (which creates a sluggish movement), diabetes (often associated with gastroparesis or slowed stomach emptying).
And of course, close to my heart is Ehlers Danlos Syndrome which is a connective tissue disorder which potentially affects both the distribution of the Interstitial Cells of Cajal and also the responsiveness of the muscular tissue to which they are connected. Additionally, the relationship of the nervous system to these cells means that other neurologically-related conditions can affect the function of the ICC and MMC.
Stress and the Migrating Motor Complex
You will know if you have read my previous writings about healing autoimmunity that I have a deep respect for the role of mental, emotional and spiritual distress in the journey to health and recovery. However, my first insistence when dealing with a client for whom trauma, emotional distress and psychological issues form part of their complexity of issues, is that there aren’t any underlying features of physiological challenge which can be feeding their mental and emotional issues. SIBO is one of these areas where stress is both a contributing factor to mental health and psychological concerns, but can also be exacerbated by mental anxiety and stress.
In the digestive tract, parasympathetic nervous system tone and activity is key. “Rest and Digest” is associated with parasympathetic activity, for obvious reasons: this is the branch of the nervous system that helps with both switching off the adrenalised active nature of ourselves, but it is also responsible for the innervation of the digestive tract. Therefore in high-stress situations, where the mind and emotions (and life circumstances) are keeping the psyche in high alert, parasympathetic activity is quelled. This results in a slowed transit, reduced absorption, lower stomach acid levels and enzymes and impaired digestive function overall. So stress can cause slowed transit time and impaired GI function and can contribute to all of the factors that give rise to SIBO. However, SIBO can also cause stress – in two very direct ways. The most obvious is that being in constant digestive pain, distress, distention and discomfort is actually quite stressful. I regularly deal with the psychology of healing with my clients, and the presence of constant symptoms which affect quality of life is a huge factor affecting the emotional and mental wellbeing. Symptoms CAUSE stress a lot of the time. The second factor is that inflammation and immune conditions within the bowel which are accompanied by bacterial issues give rise to increased levels of Lipopolysaccharides (LPS), which is just a type of endotoxin produced by bacteria. Raised LPS levels trigger the release of inflammatory cytokines, but also, once released, these endotoxins have been shown to have systemic effects throughout the body – causing issues from arthritis in joints, tingling in nerve endings, flushing in capillaries near the skin surface… and also altering mood and cognition through affecting the vagus nerve and also causing neuroinflammation. Therefore, I regularly see that a patient with SIBO who has been through intense gastrointestinal distress, often having tried several dietary approaches which have failed, presents as a nervous and hyper-sensitive individual. There is often a good degree of fear: fear of treatments and if they don’t work, fear of the length of time that treatment might take, fear of all foods, fear of eating. Food phobia, so often seen as a psychological phenomenon, is highly correlated with such digestive issues, in my experience. I have even had clients hesitant to even do the testing for SIBO because it requires a special diet for a few days before the tests and this alone has completely freaked them out.
Can We Treat SIBO?
Because SIBO is close to my heart I stay on the edge of the research and the treatment understandings in this area. The truth is that SIBO can be tricky, it can be recalcitrant – and depending on the real ‘cause’ (i.e. adhesions and structural abnormalities vs. functional concerns such as hypothyroidism and diabetes) there are different treatment protocols and expected healing trajectories. Remission and relapse phases are almost to be expected – particularly if, for any reason, you have a persistent underlying cause (or indeed, there is some uncertainty about what your specific underlying cause might be). There is, however, life beyond the agony and the constant issues of SIBO. If you, or someone you know, is confused about whether this is part of the picture of your health, I would encourage you to contact a Functional Medicine practitioner who can help you. SIBO is not really something that can be treated using a ‘cookie-cutter’ online protocol. There are variations in antibiotics (prescriptions, herbal treatments and all associated therapeutic supplements) and also variations in recommended diets to help tackle this condition. This really is not a condition that should be tackled alone, or just using an internet plan. If you’re interested in my help then please do contact me. There is real distress and a hidden epidemic of people who suffer through their GI problems, frightened to eat ‘off-plan’ in case of symptoms. In my next post I am going to highlight one of the key ways I have seen SIBO flying under the radar in my clients, so do sign up (top right of this page) to receive my updates. If you’d like to see if SIBO is perhaps a key for you – we can arrange a consultation and fully go through all of your symptoms and concerns to see whether the answers you need for your health lie in treating this condition.