Low FODMAP diets are gaining recognition as an effective way to manage Irritable Bowel Syndrome (IBS); however, very little research exists about following a low FODMAP diet as a vegan.
This article reviews what a low FODMAP diet is, and important considerations for vegans who may be interested in trying the diet to manage their IBS.
Always seek medical advice from your primary care provider before making dietary changes. Due to its restrictive nature, the low FODMAP diet should only be used under the close supervision of a Registered Dietitian or other qualified professional.
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If you haven’t done so already, I recommend reading my article about IBS and a vegan diet before continuing with this post.
What are FODMAPs?
In recent years there has been growing interest in FODMAPs, and specifically the low FODMAP diet as a way to manage Irritable Bowel Syndrome (IBS).
FODMAP is an acronym that stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols. These terms represent a group of carbohydrates that may be poorly digested and/or absorbed when travelling through the digestive tract. This can lead to adverse effects in the digestive tract of some people, potentially creating symptoms associated with IBS 1.
Please note this does not mean that carbohydrates are “bad”, but some people may have difficulty digesting certain types of carbohydrates.
Types of FODMAPs
Here’s a brief overview of each type of FODMAP and short list of foods that contain higher levels of that FODMAP. These food lists are not exhaustive and there are many other high FODMAP foods in each category.
- Oligosaccharides: Includes fructans and galacto-oligossacharides (GOS) which are naturally found in foods including legumes, nuts, artichokes, onion, garlic, wheat, and rye products.
- Disaccharides: Includes lactose, the sugar found in milk products and requires the enzyme lactase for absorption. Individuals with adequate lactase production can digest lactose, and therefore are not required to restrict lactose from their diet.
- Monosaccharides: Includes fructose which is naturally found apples, pears, watermelon, mango, honey and sugar snap peas. Fructose is also used as a commercial sweetener as fructose or high fructose corn syrup.
- Polyols: Sugar alcohols that include sorbitol, xylitol, mannitol, maltitol. They can be found naturally in foods such as apples, pears, and stone fruits. However, they’re often added to food as artificial sweeteners such as chewing gum, mints, and sugar free or diabetic products. Sugar alcohols are becoming a more popular way to sweeten other products such as protein powders or energy bars, some of which contain very high amounts of this FODMAP.
FODMAPs are naturally found in foods such as fruits, vegetables, legumes, honey, dairy products and sweeteners. Many of these foods are nutritious and staples for ensuring proper nutrition on a plant-based diet. This can make navigating an IBS diagnosis particularly challenging for vegans, which is why it's so important to seek a nutrition professional if you are interested in exploring how a low FODMAP vegan diet could help your IBS symptoms.
It's important to reiterate that these foods are not inherently “bad” or “unhealthy”. It just means that some people have difficulty properly digesting and/or absorbing these components in food. When it comes to FODMAPs, the amount consumed in one meal can also make a huge difference.
How FODMAPs Trigger IBS Symptoms
There are two major ways FODMAPs could trigger IBS symptoms in people who are sensitive to high FODMAP foods:
- FODMAPs are not digested (not broken down properly or in large enough quantities). As these whole, undigested FODMAPs travel through the digestive tract they attract water which can cause symptoms such as bloating and discomfort. Essentially, water can get pulled into the intestines if high levels of FODMAPs are present.
- FODMAPs are not absorbed (or not absorbed in large enough quantities). If unabsorbed FODMAPS reach the large intestines, they’re rapidly fermented by bacteria for fuel; hence the F in FODMAP standing for “fermentable”. This results in gas production which triggers IBS symptoms such as bloating, abdominal pain, and discomfort 1, 2.
All FODMAPs are potential triggers for IBS, however everyone may react to FODMAP compounds differently. The amount of FODMAPs consumed also plays an important role. Someone may tolerate a larger amount of one FODMAP compound and a smaller amount of another 3.
To figure out which foods (in what amounts) trigger symptoms for an individual, it’s common to trial a low FODMAP diet under the guidance of a dietitian or qualified nutrition professional.
Low FODMAP Diet
The low FODMAP diet is becoming recognized as an effective dietary management strategy for IBS, but is not a one-size-fits-all approach, nor a diet meant for life 4.
Current research suggests that the low FODMAP diet can provide significant IBS symptom relief compared to other therapeutic diets and treatments 3.
The low FODMAP diet is not just an avoidance or elimination diet. The diet’s three phases provide information to individuals who have IBS about personal tolerance level for FODMAP foods. This enables the person to modify their intake of newly discovered food triggers for long-term management and relief of IBS symptoms.
Individuals should implement the low FODMAP diet under the expert guidance of a dietitian. The dietitian will first take a detailed history of IBS symptoms and usual intake. Based on information provided, the dietitian will individualize and tailor the low FODMAP diet accordingly 4.
The low FODMAP diet is not appropriate for everyone because it’s highly restrictive (albeit temporary). Since vegans already have a more limited diet, there are further concerns for nutrition adequacy when trialing the diet.
The low FODMAP diet is a three-phase process which includes: 5
Elimination Phase
The elimination phase is a strict restriction of all high FODMAP-containing foods for 4-8 weeks. The elimination phase is highly restrictive, therefore guidance from a dietitian during this phase is crucial to ensure adequate nutrition.
The elimination phase has been shown to improve symptoms for 75% of people with IBS within 6 weeks 4. The diet’s restrictive phase should only continue until symptoms improve. The length of time for this phase, and degree of symptom improvement, will vary between individuals 6.
This is the most challenging phase of a low FODMAP diet. Even though it’s temporary, it can lead to increased stress and/ or anxiety. Being prepared, and working with a dietitian, can help mitigate the difficulty of this phase.
Managing stress and anxiety while implementing the low FODMAP diet is important as these are two common triggers of IBS symptoms.
Individuals on the low FODMAP diet, especially during the elimination phase, will have to shop for, cook and prepare most of their meals. It can be extremely challenging to eat out while on the elimination phase of a low FODMAP diet, so prepare to eat at home most of the time. When eating outside the house, you may need to prepare meals in advance and bring them with you.
Many vegans understand the challenge of eating with fewer options outside the home, so this may not be a huge change from normal. Just know that many convenience options will not be available during the elimination phase.
If you require support, contact a dietitian to guide and educate you during this process!
Once symptoms improve, it’s important to move onto the reintroduction phase. The most common mistake people make when following a low FODMAP diet is staying in the elimination phase. This is NOT meant to be a long-term elimination of all high FODMAP foods, and it is critical to move through to the next phases.
Reintroduction Phase
During the reintroduction phase, foods high in FODMAPs are gradually reintroduced to identify tolerance. Typically, one category of FODMAP foods is introduced at a time (ex. starting to reintroduce foods high in monosaccharides before foods high in oligosaccharides).
It’s important to monitor (and record) symptom types and severity during this phase while remaining on a low FODMAP diet and reintroducing high FODMAP content foods one at a time. Each introduction is completed over a three-day period 6.
Individuals should take a three-day break in between each introduction to ensure no cross over effects occur 6. Once tolerance of certain FODMAPs is identified, the next step is to investigate their tolerance at higher doses, increased frequency, and when combined with other high FODMAP foods 6.
For those who have additional dietary requirements, such as vegans, a dietitian is essential. Dietitians can help reintroduce foods of highest nutritional concern first. For example, legumes are higher in FODMAPs but contain important nutrients for vegans. Therefore, a dietitian could implement legumes early during the reintroduction phase to assess tolerance and ensure daily protein requirements are being met 6.
Not every person will react to all FODMAPs. This is important to learn so you can add these foods back into your diet. This phase also allows you to learn the volume or frequency of certain high FODMAP foods you can tolerate. For example, someone may find they can eat ½ C of chickpeas and be fine, but a full cup is too much in one meal or day.
Personalization Phase
Once the reintroduction phase is complete, individuals are encouraged to follow their own modified version of the low FODMAP diet. At this time individuals will be more informed about their personal tolerance and triggers.
This modified low FODMAP diet will not be as restrictive as the elimination phase, considering this diet is only as restrictive as one’s symptoms require 6. Many people can add some amounts of high FODMAP foods back in, so it’s critical to move through the reintroduction phase to figure out the amounts and types of high FODMAP foods you can tolerate.
Since high FODMAP foods are generally nutritious, it’s helpful to include them in your diet if possible.
Nutritional adequacy has been a concern for those on a low FODMAP diet, especially during the elimination phase. However, in the long-term, a modified low FODMAP diet seems to be nutritionally adequate for most individuals 5. Keep in mind there hasn’t been any studies of low FODMAP diets in vegans (to my knowledge).
Since there aren’t many resources available for vegans with IBS, it’s important to work with a dietitian who can help ensure nutritional adequacy through all phases of the diet.
Low FODMAP Diet and Vegan Foods
Restrictive diets like the low FODMAP diet increase the risk of nutritional inadequacy.
For vegans, this risk is amplified, considering many vegan friendly nutrient-dense options are high in FODMAPs.
Vegans solely rely on plant-based products for dietary protein, making it a challenge for vegans to reach their daily requirement of protein when high FODMAP foods like legumes are removed.
Beyond protein, other potential nutrients of concern for vegans on a low FODMAP diet include overall energy intake, fiber, iron, calcium and zinc 3.
However, researchers have tested FODMAP content in common vegan foods. Vegan protein sources such as soy cheese, tempeh, pea protein, rice protein, false chicken (potentially other vegan mock-meat products) and vegan egg yolk or egg replacer were found to be low in FODMAPs. In addition, other vegan or vegetarian friendly foods low in FODMAPs included macadamia milk, canned coconut milk, nutritional yeast, dulse and kelp noodles 7.
Furthermore, the FODMAP content of soy products seems to be variable. Firm tofu and soy protein-based soy milk are low in FODMAPs compared to silken tofu and whole soybean-based soy milk 7.
The level maturity of the soybean itself can influence the FODMAP content too. For example, edamame (soybeans that have not yet reached maturity) are low in FODMAPs unlike matured soybeans.
Food processing and cooking can lower FODMAP content too. For example, pickling and sprouting lowered FODMAP content of foods.
Canned legumes (ex. red kidney beans) were shown to be lower in FODMAP content too compared to dried forms 7. In addition, straining and cooking legumes for a specific amount of time reduced the FODMAP content. For example, it was demonstrated that cooking lentils for 5 minutes and straining them reduced FODMAP content by 43% 7.
Although these foods are avoided during the elimination phase of a low FODMAP diet, knowing how processing methods lower FODMAP content can be beneficial in improving tolerance for individuals with IBS. It can be helpful to try several cooking methods during the reintroduction or personalization phases to help fine-tune tolerance levels and liberalize the diet as much as possible. This can provide more nutritious food options for vegans and help ensure nutritional adequacy long-term.
However, a low FODMAP diet led by a dietitian will ensure adequate nutrient intake despite the restriction of nutrient dense foods. If required, your dietitian will recommend supplementation to ensure daily nutrient requirements are being met.
Long-term Implications of a Low FODMAP Diet
The low FODMAP diet is a complex and restrictive diet, therefore it’s no surprise that concerns have been raised about following the diet long-term.
A study reported long-term implications of the low FODMAP diet while following dietitian led education. It was determined that individuals educated by the dietitian were equipped to continue a modified low-FODMAP diet and manage their symptoms long-term. In fact, 57% reported long-term symptom relief 8.
Furthermore, participants found that the modified low-FODMAP diet is achievable and did not negatively impact their food related quality of life or use of healthcare resources 8.
Keep in mind this research featured people following traditional, non-vegan diets which provides additional food options. Vegans could still have a fairly restrictive diet even after reintroduction, depending on symptom severity.
It’s also important to note that the researchers looked at people who worked with a dietitian and completed all 3 phases. The most common mistake people make with the low FODMAP diet is staying in the elimination phase which is NOT meant to be followed long-term. Reintroduction is critical to ensure an individual has the widest range of food options, allowing for better nutrition and easier long-term management of their IBS symptoms.
However, the low FODMAP diet does not improve symptoms in all individuals with IBS. In the event of a poor response, other dietary, psychological and pharmacological treatments should be considered with assistance from your primary care provider 9.
If the low FODMAP diet does not suit your lifestyle or needs, please contact your healthcare provider or dietitian for more information on other treatment options.
Summary: Low FODMAP Diet for Vegans
The low FODMAP diet is an effective dietary intervention for those diagnosed with Irritable Bowel Syndrome (IBS). Its long-term goal is to find a balance between symptom relief and a varied diet that meets intake requirements.
For vegans, the low FODMAP diet may be a challenge, but it’s not impossible! Guidance by a dietitian can be essential to success, because if not properly managed, the low FODMAP diet could adversely affect one’s nutritional status.
The elimination phase of the low FODMAP diet is not a diet for life. It’s important that individuals are aware that once they achieve symptom relief, the next steps of food reintroduction and personalization need to happen.
References cited:
Please note that this is a curated list of references for the topics above and not intended to be comprehensive.
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