For individuals managing Irritable Bowel Syndrome (IBS) or other gastrointestinal disorders, the low FODMAP diet is often recommended to alleviate uncomfortable symptoms like bloating, gas, and abdominal pain. FODMAPs (Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols) are specific types of carbohydrates that are poorly absorbed in the small intestine. These carbohydrates are fermentable short-chain carbohydrates. Translated, that means two things: They are sugar molecules that are linked together in chains, and they are fermentable by the bacteria in your gut. While this dietary approach can be highly effective, it often raises concerns about adequate fiber intake. Fiber is an essential nutrient that plays a crucial role in maintaining a healthy digestive system. Fiber truly is the foundation of a gut healthy diet. It is important to add more fiber into someone’s low fodmap diet because fiber directly boosts digestive health, further supporting the gut health crisis of those who follow a low fodmap diet. This article explores strategies and food choices to ensure sufficient fiber consumption while adhering to a low FODMAP diet.
The Importance of Fiber
Fiber is vital for overall health, aiding in digestion, regulating blood sugar levels, promoting satiety, and reducing the risk of chronic diseases. Fiber is an essential nutrient that plays a crucial role in maintaining a healthy digestive system. It is important to add more fiber into someone’s low fodmap diet because fiber directly boosts digestive health, further supporting the gut health crisis of those who follow a low fodmap diet. Consuming different types of fibre is important to keep our bodies healthy, and can help reduce constipation, diarrhoea, and irritable bowel syndrome (IBS) symptoms.
Recommended Intake
The USDA’s Dietary Guidelines for Americans provide specific recommendations for daily fiber intake based on age and gender. These recommendations aim to help people achieve optimal health benefits, such as improved digestion, reduced cardiovascular disease risk, and better blood sugar regulation. Despite recommendations that adult women consume 25g fibre per day and men consume 38g fibre per day, 95% of Americans eat less than this and the average fibre intake is just 16g fibre per day. People with IBS often consume even less fiber, reducing their intake to avoid triggering symptoms.
Soluble vs. Insoluble Fiber
There are two primary types of fiber: soluble and insoluble. It’s worth noting that while we often classify fiber as soluble or insoluble, this categorization isn’t directly related to FODMAPs.
- Soluble Fiber: Soluble fibre is found in some vegetables and fruits, oats, and in legumes like beans, peas and lentils. Soluble fiber acts like a sponge by absorbing liquid, and by making bowel movements softer and easier to move. Soluble fibre can help slow the digestion of food, manage diarrhoea, and reduce irritable bowel syndrome symptoms. Soluble fibre also acts as a gut prebiotic because it feeds gut bacteria and promotes gut health. Soluble fibers form a gel in the gut, helping eliminate unwanted substances. However, when gut bacteria feed on the high FODMAP soluble fibre like inulin, they produce gas which can cause IBS symptoms.
- Insoluble Fiber: Insoluble fibre is found in the skins of vegetables and fruit, brown rice and the bran portion of whole grains. Insoluble fiber adds physical bulk to your stools and helps to speed up the removal of waste from your gut. Insoluble fibers clean the gut lining. General practitioners often recommend increasing fibre, normally through an insoluble fibre supplement to help manage IBS symptoms . However, research indicates that many IBS patients do not tolerate insoluble fibre (like bran), and that increasing the insoluble fibre in their diets could worsen IBS symptoms.
We need to consume a mixture of both soluble and insoluble fibre each day. To help fibre work properly in your gut you need to drink between 4 to 6 glasses of water per day to prevent gas, bloating and diarrhoea . It is important that you increase high fibre foods gradually to give your body a chance to adjust. If you struggle with foods high in insoluble fibre, then choose more foods from the ‘Low FODMAP Foods Higher in Soluble Fibre’ table at the bottom of the page - just make sure you stick to the low FODMAP serving sizes in the Monash Low FODMAP app.
Read also: High-Fiber Diet for Better Health
Challenges of Getting Enough Fiber on a Low FODMAP Diet
Now that we have established the benefits of a high fiber diet, it’s important to recognize that the low FODMAP diet is notoriously low in fiber. This is because so many high fiber foods - including beans and legumes, certain fruits and nuts, cruciferous vegetables, as well as wheat - are all restricted. The low FODMAP diet temporarily restricts these carbohydrates in order to relieve uncomfortable symptoms and give your digestive system a rest. Removing irritants gives your gut lining a chance to repair itself and can help restore a healthy balance of gut flora. Since the diet focuses on gut health and digestive wellness, it’s essential to maintain that balance in mind and help manage your IBS by introducing high-fiber, Low FODMAP foods that can help get things moving.
There are a number of reasons for this poor fibre intake, including the uptake of gluten-free, wheat-free, and grain-free diets which limit or eliminate fibre-rich grains from the diet; and beliefs that high fibre foods are expensive, unpalatable, and complicated to prepare.
Strategies for Increasing Fiber Intake on a Low FODMAP Diet
Maintaining a low FODMAP diet while ensuring adequate fiber intake may seem challenging, but it’s absolutely achievable when the right approach is taken. Here are several strategies to help you navigate this dietary balance:
1. Choose Low-FODMAP Fiber Sources
The first strategy is to choose low-FODMAP fiber sources. Fortunately, there are plenty of high fiber low FODMAP foods that can be included in your diet. Some low-FODMAP vegetables include carrots, zucchini, green beans, and potatoes, while some low-FODMAP fruits include strawberries, blueberries, kiwis, and oranges. Grains such as oats, quinoa, and brown rice are low-FODMAP options that contain significant amounts of fiber.
- Vegetables: corn, eggplant, green beans, broccoli, spinach, kale. Aim to have at least five serves of low FODMAP vegetables per day.
- Fruits: “ firm bananas, raspberries, rhubarb, kiwifruit, mandarin, strawberries, passionfruit and oranges”. Aim to have two serves of low FODMAP fruit per day.
- Grains: quinoa, brown rice, oats (in limited amounts), gluten free breads and cereals. Aim to have four to six servings of whole grain products per day.
2. Manage Portion Sizes
When starting to add more fiber into the diet while experiencing sensitivity to FODMAPs, it is important to make sure that the fiber foods you are consuming are eaten in portion sizes that fall within the green level of FODMAP content. To increase the amount of fiber foods that you are able to tolerate in one sitting, try to eat small servings of several different fiber foods rather than relying on a large serving of a single food to provide the fiber for your meal. When we do this, we are helping to avoid FODMAP stacking, which can cause GI upset. Additionally, it can be helpful to spread out fiber intake evenly throughout the day instead of focusing on high-fiber foods during only one meal or snack.
Read also: Guide to Keto Fiber
3. Be Mindful of Cooking and Preparation Methods
The last strategy is to be mindful of ways to reduce FODMAP content when cooking or preparing foods. Pickling certain higher FODMAP foods such as onions, garlic, and beets has been shown to reduce their FODMAP content by up to 80% making them suitable for a low FODMAP diet. Beets are high in fiber, so this is a great option that may work for you if you can tolerate beets. Certain cooking methods such as boiling can also help to reduce FODMAP content in certain foods. For example, boiling legumes such as lentils, or beans can reduce their FODMAP content and may make them more tolerable, especially if they are pre-soaked.
4. Gradually Increase Fiber Intake
For those with IBS or other digestive issues, gradually increasing fiber intake by a few grams per week helps prevent bloating, gas, and discomfort. Transitioning from a low to a high-fiber diet overnight is like attempting a marathon without training-it’s likely to cause discomfort and setbacks. Just as you wouldn’t lift heavy weights without building strength gradually, your digestive system needs time to adjust to more fiber. For those with IBS, this careful approach is even more critical, especially when incorporating low FODMAP high-fiber foods. Gradually increasing fiber intake prevents gastrointestinal (GI) symptom flare-ups.
The duration at each step can vary from 2 to 7 days, depending on individual tolerance. Begin by adding one slice of low FODMAP whole grain bread daily, gradually increasing to two slices. Increase low FODMAP fresh fruits and vegetables intake by starting with one serving of each daily, adding one serving per week as tolerated. Add 1-2 tablespoons of chia or flaxseeds into nondairy or lactose-free yogurt, cereal, smoothies, or fruit salads. Finally, consider adding a fiber product daily once adapted to the high-fiber diet.
5. Stay Hydrated
Drinking enough water is crucial when you increase your fiber intake to help with digestion and avoid discomfort. It’s recommended to drink at least 8 cups of water daily or half your body weight in ounces. To help fibre work properly in your gut you need to drink between 4 to 6 glasses of water per day to prevent gas, bloating and diarrhoea.
Low FODMAP, High-Fiber Food Choices
Here's a list of high fiber low FODMAP foods that can be included in your diet.
Read also: Gut Health on Carnivore Diet
High-Fiber Vegetables
Some low-FODMAP vegetables include carrots, zucchini, green beans, and potatoes.
- Carrots
- Zucchini
- Green beans
- Spinach
- Kale
- Eggplant
- Corn
High-Fiber Fruits
Some low-FODMAP fruits include strawberries, blueberries, kiwis, and oranges.
- Strawberries
- Blueberries
- Kiwis
- Oranges
- Firm bananas
- Raspberries
- Rhubarb
- Mandarin
- Passionfruit
High-Fiber Grains and Seeds
Grains such as oats, quinoa, and brown rice are low-FODMAP options that contain significant amounts of fiber.
- Oats (in limited amounts)
- Quinoa
- Brown rice
- Gluten-free breads and cereals
- Ground flaxseed
- Chia seeds
Other Fiber Sources
- Nuts and seeds (in moderation): Almonds, chia seeds, flaxseeds, and walnuts are good sources of fiber.
- Legumes (in limited quantities): A low FODMAP serving size of canned chickpeas is 1/4 cup and the safe serving size of canned lentils is 1/4 cup. Add safe serving sizes of canned chickpeas and lentils to salads and casseroles.
Low FODMAP Meal Ideas
Here are some meal ideas to incorporate high-fiber, low-FODMAP foods:
- Quinoa Salad with Toasted Almonds and Chickpeas: Create a quinoa salad with cucumber, bell peppers, and cherry tomatoes. Add toasted almonds and canned drained and rinsed chickpeas for protein and crunch.
- Pecan-Crusted Tofu: Coat firm tofu slices with crushed pecans mixed with gluten-free breadcrumbs, then bake until golden brown.
- Millet-Stuffed Bell Peppers: Cook millet with diced carrots, zucchini, and spinach. Stuff the mixture into halved bell peppers and bake until tender.
- Oat and Teff Breakfast Bowl: Cook a mixture of oats and teff in lactose-free milk until creamy.
- Tempeh Stir-Fry with Polenta: Stir-fry tempeh with low FODMAP veggies like bok choy, carrots, and green beans in a gluten-free soy sauce.
Fiber Supplements
When aiming to increase fiber intake on a low FODMAP diet, some people find it tricky to meet their needs solely through food. The sneaky option to upping your fiber intake while on the Low FODMAP diet is to try adding a fiber supplement to your daily routine. Although we don’t officially endorse any specific brands, there are definitely a few out there that are labelled “Low FODMAP fiber supplements.” All you have to do is look!
- Rice bran and oat bran are low FODMAP fibre supplements that can be used on the Low FODMAP diet.
- Kate Scarlata, a registered dietitian well known for her specialisation in the low FODMAP diet, recommends using chia seeds as a fibre supplement as one tablespoon has five grams of fibre.
- Dr Jane Varney, from Monash University, recommends choosing a fibre supplement made from sterculia . She recommends this fibre because it is considered “less ‘gas forming’ than other fibre supplements”, which means it may help to treat constipation in people with IBS.
- Other research suggests that the use of psyllium husk, as a dietary supplement to increase soluble fibre, can help to reduce IBS symptoms in some patients. However, psyllium may not suit those with SIBO, as it can potentially worsen symptoms. It’s my top recommendation for many of my clients.
- Avoid using fibre supplements that contain wheat bran, All Bran, inulin and chicory root as these are high FODMAP ingredients.
Additional Tips for Healthy Bowel Habits
- Eat a varied, high fibre diet that includes fibrous foods such as fruit, vegetables, nuts, seeds and pulses.
- Keep active.