Nutrition for IBS on a Plant-Based Diet
June 3, 2022
If you are struggling with irritable bowel syndrome (IBS) on a plant-based diet then you aren’t alone. It’s estimated that about 1 in 7 people suffer from IBS worldwide but this number is likely much higher as many go undiagnosed (1).
The world of IBS can be challenging to navigate as it is but having IBS on a plant-based diet can be even more overwhelming. This article will take you through everything you need to know about managing your IBS on a plant-based diet.
Firstly, what is IBS?
Irritable bowel syndrome (or IBS) is a chronic condition that affects how the large intestine works. It is a ‘functional gut disorder’, meaning that there is no recognisable damage to your digestive tract, however, it still isn’t functioning correctly.
It isn’t entirely well understood what causes IBS yet, but there are 4 main mechanisms that may be at play:
- Altered gut motility where food passes through your digestive system either too quickly or too slowly, often causing diarrhoea or constipation
- Bacterial dysbiosis which means there is an imbalance between your good and bad gut bacteria
- Gut-related infections
- Increased gut sensitivity
This can cause a range of unpleasant symptoms such as bloating, abdominal pain, constipation, diarrhoea, fatigue, nausea and excessive flatulence. You may experience anywhere from one to all of these symptoms at varying degrees of severity (2).
Whilst these symptoms aren’t directly causing damage or inflammation, they can still significantly affect your day-to-day living and overall quality of life.
Because symptoms are so varied between different people, IBS can be difficult to diagnose and can take years. There are currently no accurate medical diagnostic tests available. At this stage, diagnosis of IBS happens through a process of elimination by assessing for more serious conditions first such as coeliac disease, Crohn’s Disease, ulcerative colitis, endometriosis, adenomyosis or bowel cancer.
Who is at risk of developing IBS?
- Women are more susceptible than men
- Family history of IBS – may be due to a genetic component or having similar food/environmental exposures
- Women with endometriosis are 3.5x more likely to also have IBS
- If you have anxiety, depression or other mental health struggles or are experiencing a lot of stress
- If you have recently experienced a foodborne illness or parasite (post-infectious IBS)
How does plant-based eating affect IBS?
When it comes to plant-based diets and IBS, there are both pros and cons.
On one hand, plant-based diets are mostly made up of plant foods so they tend to be naturally higher in fibre, which helps feed our good gut bacteria necessary for a healthy gut. Getting enough fibre is also one of the best ways to prevent constipation which is a common IBS symptom.
On the other hand, following a plant-based diet may also make IBS symptoms worse, especially gas and bloating.
Plant-based meals are often quite large in volume which can exacerbate bloating and abdominal distention after meals.
The high fibre content of plant-based diets can be a double-edged sword. Although fibre plays a key role in promoting good gut health, too much fibre can trigger symptoms such as bloating and abdominal pain in some individuals with a more sensitive gut. Especially if you have recently adopted a plant-based diet and are not used to eating so much fibre.
Plant-based diets are also quite high in many foods that may trigger IBS symptoms such as high ‘FODMAP’ foods.
IBS and the low FODMAP diet
If you have been diagnosed with IBS, it’s likely that you’ve come across the low FODMAP diet, either through your doctor or your own research. It is often one of the first dietary strategies promoted to help you improve symptoms, but without professional guidance, it can often be overwhelming and confusing to navigate on your own.
What are FODMAPs?
FODMAPs are types of carbohydrates found in many common (and nutritious) foods such as fruit and veg, legumes, nuts and seeds, whole grains and dairy. However, when we eat them, they are not digested well by the body. Instead, they stay in our large intestine and go down one of two paths.
- Some FODMAPs draw water into the intestines which can cause diarrhoea or increased pressure in your gut, leading to bloating or discomfort.
- FODMAPs may also be fermented by the bacteria living in our gut, which creates gas as a by-product. Whilst this is a very normal and healthy process, for those with IBS, this can trigger symptoms such as bloating, excessive flatulence, pain or discomfort.
There are a few different types of FODMAPs in the diet. FODMAP is an acronym which stands for:
Oligosaccharides (fructans, galacto-oligosaccharides aka GOS) – found in many legumes and nuts, wheat and vegetables such as onion and garlic
Disaccharides (lactose) – found in dairy products
Monosaccharides (fructose) – found in high amounts in some fruit and veg such as apples, pears, mango and sugar snap peas as well as honey
Polyols (sorbitol, mannitol, xylitol) – found naturally in foods such as mushrooms and stone fruit and also commonly added as artificial sweeteners in sugar-free products
All FODMAPs have the potential to trigger IBS symptoms, but the types you react to and in what amounts will be different for everyone. The best way to identify this is by trialling the low FODMAP diet.
The stages of the low FODMAP diet
1: Elimination Phase
During this phase, all high FODMAP foods are eliminated from the diet. This phase should be followed strictly for 2-6 weeks or until symptoms have resolved. If there is no symptom improvement within this period, it should be discontinued to trial other diet or lifestyle strategies (with more on this later).
2: Re-introduction or Challenge Phase
If your symptoms resolve during phase one, then you may move on to phase two. During this phase, high FODMAP foods are challenged to determine the type and amount of FODMAPs that you can tolerate without triggering symptoms.
3: Diet Personalisation Phase
In this final phase, a personalised FODMAP diet is established based on the results of your challenges. It incorporates all the FODMAPs that you tolerate whilst only avoiding those that trigger your symptoms to allow for a greater diet diversity.
Because the low FODMAP diet is challenging to do correctly and has risks including developing nutrient deficiencies and disrupting the balance of good gut bacteria, it is recommended that it should be followed under the guidance of an Accredited Practicing Dietitian with training in the area. All of our dietitians at Plant Nutrition and Wellness are trained in the low FODMAP diet by Monash University.
Can you follow low FODMAP on a plant-based or vegan diet?
Whilst you can follow a low FODMAP diet as a vegan, it does come with added challenges. This is because vegan diets are made up mostly of plant-based foods such as fruit and veg, legumes, nuts, seeds and whole grains (which, as mentioned before, often happen to be high in FODMAPs).
This means that when following a vegan or a plant-based diet, you will likely be consuming a larger volume of high FODMAP foods than someone following an omnivore diet incorporating animal foods (which are low FODMAP with the exception of dairy which contains lactose).
Meeting protein needs
It can be challenging to meet your protein needs on a vegan or plant-based low FODMAP diet as a large proportion of plant-based protein sources such as beans and legumes, nuts and seeds and mock meats are high in FODMAPs compared to non-vegan proteins such as meat and eggs.
Risk of nutrient deficiencies
The next challenge is the risk of nutrient (vitamin and mineral) deficiencies. Plant-based diets, as with all diets that restrict certain foods, have an increased risk of not meeting your requirements for some nutrients such as vitamin B12, iron, zinc, calcium, protein and omega 3s.
Following a low FODMAP diet adds a further degree of restriction which amplifies this risk. The restrictive nature also means that it can be difficult to meet your energy (calorie) needs (9).
Identifying low FODMAP plant-based foods
Not only does following a low FODMAP diet as a plant-based eater put you at risk of not meeting your energy and nutrient needs, but it can also make it challenging to work out what you actually can eat in the first place!
The low FODMAP diet app designed by Monash University can be a great tool to help you get started with a comprehensive database of high and low FODMAP foods. It includes recipe ideas (including a few vegan options).
We have also put together a list of high and low FODMAP plant-based foods below.
NOTE: limit fruit to 1 cup and juice to ½ cup per serve then leave at least 3 hours between serves.
Nuts and Seeds
Low FODMAP certified snacks e.g.
We strongly recommend working with a dietitian experienced in managing IBS on a plant-based diet (for example, our team at The PNW Clinic) rather than attempting a low FODMAP diet on your own, as they will be able to provide some great low FODMAP meal and snack ideas as well as any necessary supplements to make sure your nutrition needs are met.
When is the low FODMAP diet not appropriate?
Just because you have IBS, it doesn’t mean you need to go down the low FODMAP route. In some cases, it can be harmful to your health and wellbeing to do so, often due to its restrictive nature.
The low FODMAP diet may not be suitable for the following individuals:
- Babies and children
- Those who are pregnant or breastfeeding
- Those who have certain other medical conditions
- Current or history of eating disorders, disordered eating or poor relationship with food
- At risk of an eating disorder
- If you have too many other dietary restrictions
- Those who are underweight
If the low FODMAP diet isn’t right for you, there are a few other diet and lifestyle strategies outside of a low FODMAP diet that can have an equally significant impact on reducing your symptoms. These are called ‘first-line’ strategies and we would usually trial these first for most clients (if appropriate) before trialling the low FODMAP diet.
First-line strategies for IBS
Just because you have IBS, it doesn’t mean that your symptoms are occurring because of a FODMAP intolerance. In fact, the key to your symptom relief may be as simple as making a few changes to your diet and lifestyle such as adjusting your caffeine and fibre intake or altering your eating environment (10).
Some first-line strategies we might recommend trialling include:
For bloating and abdominal pain
- Avoid skipping meals or leaving long gaps between them – try the rule of 3:
- 3 meals and 3 snacks every 3-4 hours
- Take your time to eat mindfully and avoid other distractions whilst eating
- Chew your food well to applesauce consistency before swallowing
- Avoid large meals
- Avoid swallowing excess air by slowing down your pace and avoiding straws, chewing gum and fizzy beverages
- Avoid tight waistbands
- Regular exercise and stretching – get up and move around every hour if you can (try setting a phone reminder to help)
- Avoid sugar alcohols (xylitol, mannitol, erythritol, sorbitol, isomalt) commonly found in sugar-free and diet products
- Aim for 30g fibre per day by including fruit, veg, whole grains, legumes, nuts and seeds at each meal
- Add in more soluble fibre: oats, barley, flax and chia seeds, psyllium husk, lentils, beetroot, sweet potato – these foods help draw water into the bowels to soften them
- Include 2 kiwi fruits daily – high in fibre plus contain an enzyme called actinidin that may help promote laxation
- Aim for 1.5-2.5L fluid per day
- Incorporate physical activity daily – this can be as simple as going for a walk
- Consider your toileting posture and routine
- Try a pelvic floor physio
- Opt for smaller more frequent meals – e.g. 6-8 small meals each day
- Potential trigger foods to limit – caffeine, high-fat meals, spicy foods, alcohol
- Ensure adequate hydration
- Try a pelvic floor physio
- Focus on including more soluble fibre – oats, barley, flax and chia seeds, psyllium husk, lentils, beetroot, sweet potato
There is increasing research that supports a link between gut health and IBS symptoms with our mood, stress levels and overall mental health.
This happens through a mechanism called the gut-brain axis. Essentially, we have a nerve called the vagus nerve which acts as a ‘communication highway’ connecting the brain and our digestive system. If you have ever experienced the sensation of ‘butterflies in your stomach’ when you get nervous, this is the gut-brain axis in action.
This means that psychological factors such as stress and anxiety can play a huge role in the onset of some of our gut-related symptoms such as bloating and diarrhoea.
As such, adopting a few stress management techniques in your daily life can play a big role when it comes to improving your IBS symptoms. What works for you may look different to what works for someone else, but a few common techniques you may like to try include:
- Taking some time out and allowing yourself to fully relax (guilt-free)
- Yoga, stretching or other forms of gentle physical activity such as walking
- Engaging in some self-care practices
- Professional support from a counsellor or psychologist
Gut-directed hypnotherapy is a more recent tool for managing IBS symptoms by working with the gut-brain axis. It is thought that in IBS, there is a miscommunication in the gut-brain axis which may play a large role in triggering symptoms.
Gut-directed hypnotherapy aims to repair the communication between the gut and the brain, subsequently relieving gut symptoms. So far, it appears to have pretty promising results with research suggesting symptom improvement in 70% of IBS patients (11).
A study conducted by Monash University (2016) compared the low FODMAP diet to gut-directed hypnotherapy in people with IBS. It found that after 6 weeks, both groups had equally significant improvements in their gut symptoms. This improvement was even maintained at the 6-month mark (12).
If you think gut-directed hypnotherapy might be for you, there are two ways you can trial it:
- You can do it in person with a psychologist trained in the area
- Alternatively, there is now a gut-directed hypnotherapy app called Nerva which is a much more cost-effective alternative (13)
With so much information available from Google searches, social media, family and friends and other health professionals, tackling your IBS can often be an overwhelming and confusing experience. Especially if you have IBS on a plant-based diet. However, if this is you, we recommend booking in with one of our dietitians to help you navigate all of the information, get to the bottom of your triggers and work out a suitable plan to help you live as symptom-free as possible without compromising your health and wellbeing.
You can book a discovery call today.
This article was written by PNW clinic dietitian Georgia D’Andrea.