I often see the question “Can a plant-based diet cure IBS?” pop up in vegan Facebook groups. Since a) April is IBS Awareness Month and b) I’m seeing ever-increasing numbers of clients with IBS and other functional gastroenterological problems in my practice, I thought I’d grab the opportunity to address this burning question.
First, what is IBS? This is an important question to answer, because I often see clients with gut problems who have been told by their GP or other health practitioner that they have IBS, but when I ask them what symptoms they’re having, it quickly emerges that they don’t have IBS at all, but rather, a different functional digestive disorder. That’s important, because in order to be able to treat a condition effectively, you need to know what it is, and what’s causing it!
Irritable bowel syndrome, or IBS, is defined by the Rome IV Diagnostic Criteria as
Recurrent abdominal pain on average at least 1 day/week in the last 3 months, associated with two or more of the following criteria:
1. Related to defecation
2. Associated with a change in the frequency of stool
3. Associated with a change in the form (appearance) of stool
(These criteria should be fulfilled for the last 3 months with symptom onset at least 6 months prior to diagnosis.) *
There are 4 subtypes of IBS:
- IBS-C: IBS with predominant constipation;
- IBS-D: IBS with predominant diarrhoea;
- IBS-M: IBS with mixed bowel habits; and
- IBS, unsubtyped.
What this means in plain language is that people with IBS suffer from abdominal pain accompanied by either overly frequent and loose stools, or constipation (infrequent and/or hard-to-pass stools), or an alternating pattern of diarrhoea and constipation. They frequently experience bloating or abdominal distention (my clients frequently complain that they look ‘6 months pregnant’ and can’t zip up their jeans by the end of the day) and abdominal cramping, and may sometimes pass mucus with their bowel movements.
IBS is characterised as a brain-gut dysfunction, in which the enteric nervous system (‘gut brain’) responds to neurological signals sent by the central nervous system (‘main brain’) in an abnormal way, causing irregular or increased contractions of the smooth muscle lining the digestive tract. In turn, the gut brain sends signals back to particular regions of the main brain that cause the person to perceive the contractions of their gut muscles as painful. This causes more signalling from the main brain which intensifies contractions in the gut, creating a vicious circle of overreaction by both brains. As a consequence, even normal contractions within the gut are perceived as painful by the brain of an IBS sufferer.
While it’s not entirely clear why this brain-gut dysfunction develops, it’s thought that either physiological trauma to the gut (for example gastroenteritis, abdominal surgery, or pregnancy) or psychological trauma may play a role. Interestingly, a history of abuse in childhood (either emotional, physical or sexual) has been linked with a higher risk of developing IBS.
Now that I’ve covered the basics of IBS, let’s return to the question with which I opened this article – can a plant-based diet cure IBS? As you may have gathered by now, the answer is that depending on the IBS subtype, switching to a plant-based diet can make IBS symptoms either better or worse, or have no effect at all, but a change in diet does not fix the underlying brain-gut dysfunction.
For people with IBS-C, including more fibre-rich plant foods in their diet will certainly help them to have softer and more regular bowel movements. IBS-D and IBS-M sufferers, on the other hand, may find that their bowel movements become even more loose and frequent.
A diet rich in fermentable carbohydrates such as fructose (found in high amounts in fruits such as apples, cherries, mangoes, watermelon and pears) and oligosaccharides (found in artichokes, asparagus and legumes) can make bloating worse in all subtypes of IBS.
Let’s be clear here: none of these carbohydrates cause IBS, but consumption of them at levels found in a healthy plant-based diet may exacerbate symptoms of pre-existing IBS.
Restriction of these fermentable carbohydrates is the basis of the low FODMAP diet which has been extensively researched by scientists at Monash University. The low FODMAP diet brings relief to anywhere between 50 and 86% of adults with IBS, according to clinical studies, and a new test may help health professionals distinguish which IBS patients are likely to experience symptom reduction from FODMAP restriction.
However, the diet can’t be followed for long without risking nutritional deficiencies (especially for vegans, given the strict limits set on legume intake), may induce eating disorders in susceptible individuals, and has adverse effects on the gut microbiome including a substantial drop in Bifidobacteria – bacterial species which are already depleted in IBS sufferers, with lower Bifidobacteria numbers associated with higher IBS pain scores.
To cap it off, a low FODMAP diet – or any other diet that restricts carbohydrates, including the Specific Carbohydrate Diet (which appears ineffective for IBS in any case), SIBO Biphasic Diet, and Paleo Autoimmune Diet, just to name a few of the most popular iterations of this genre – in no way, shape or form addresses the brain-gut dysfunction that underlies IBS.
That’s why I utilise a low FODMAP diet for the shortest practicable time to provide symptom relief to my IBS clients, while working intensively on their gut health using evidence-based prebiotics, probiotics and, where necessary, herbal antimicrobials; and also on the brain-gut axis using mind-body practices such as the Wim Hof method and other breathing techniques, yoga, and my favourite method for resolving trauma and reducing stress, EFT (Emotional Freedom Technique).
Visceral mobilisation techniques performed by a physiotherapist or osteopath can greatly assist IBS sufferers who have undergone abdominal surgery (including laparoscopy) and who developed IBS after pregnancy.
Attention to eating behaviour also plays a hugely important role in resolving IBS. Eating too quickly, drinking during meals, eating while under stress, eating too late at night and frequent snacking are all behaviours that contribute to IBS symptoms, as well as other functional gastroenterological disorders such as functional dyspepsia and functional bloating syndrome.
If you already have IBS and are thinking of adopting a plant-based diet, I would strongly recommend seeking professional advice on how to ease your dietary transition while addressing the underlying driver/s of your IBS. If you are already on a plant-based diet and are suffering IBS, you will also benefit from professional guidance – I’ve seen too many clients who, based on advice given in blogs and popular books, put themselves on such restrictive diets that by the time they come to see me, they are literally only eating 4 or 5 foods…. and have started reacting to those too!
Has IBS backed you into a corner… or chained you to the bathroom? Wondering how to tame your irritable bowels without giving up on a plant-based diet? Apply for a Roadmap to Optimal Health Consultation today!
"I was suffering from IBS flare-ups and chronic pain throughout my body. I had gone to doctor after doctor, and got scan after scan but they all came back healthy. None of the doctors I saw could help or even diagnose me – no one could understand where my almost daily migraines were coming from or the chronic pain I was feeling, and as for the IBS, I was told to live with it."
Read Lila's story "From IBS, near-daily migraines and chronic pain to pain-free and thriving".
Lila
Sydney
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