Getting Enough Fibre on the 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. However some high fibre foods are also high FODMAP and need to be removed while you are on the low FODMAP diet. This means getting enough fibre on the low FODMAP diet is important. If you are concerned about your fibre intake and IBS symptoms then talk to your doctor and dietitian. Keep reading to find out about low FODMAP fibre sources.

What is Fibre?

There are two different types of fibre:

Insoluble fibre is found in the skins of vegetables and fruit, brown rice and the bran portion of whole grains. Insoluble fibre acts as a ‘bulking agent’ for our stools which, when combined with soluble fibre, helps keep us regular (1 2). This effect is useful in the treatment of conditions such as constipation, diverticular disease and hemorrhoids (2).

General practitioners often recommend increasing fibre, normally through an insoluble fibre supplement to help manage IBS symptoms (4 5). 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 (4 5 6). This means you should speak to your doctor and a dietitian who specialises in IBS dietary management before increasing insoluble fibre.

Soluble fibre is found in some vegetables and fruits, oats, and in legumes like beans, peas and lentils (1 2). Soluble fibre acts like a sponge by absorbing liquid, and by making bowel movements softer and easier to move (1 2). Soluble fibre can help slow the digestion of food, manage diarrhoea, and reduce irritable bowel syndrome symptoms (1). Soluble fibre also acts as a gut prebiotic because it feeds gut bacteria and promotes gut health (1 7). However, when gut bacteria feed on the high FODMAP soluble fibre like inulin, they produce gas which can cause IBS symptoms (8). This is why some fibre sources are removed when on the low FODMAP diet. Soluble fibre can also help to lower blood cholesterol, improve blood glucose control, and reduce the risk of intestinal ulcers  (1 2).

Example of Foods High in Soluble or Insoluble Fibre

(Sourced from: Dietitians of Canada, 2013; NZ Nutrition Foundation, 2015; NHS Choices, 2015; Prebiotin, 2015)

See the bottom of the article for extensive lists of low FODMAP foods that are high in either soluble fibre or insoluble fibre.

How much fibre do you need per day?

We need to consume a mixture of both soluble and insoluble fibre each day (1 2). Recommended daily intake is between 25-30g of dietary fibre per day (1 2 8).

In the USA fibre guidelines are based on age:

(Table source: Institute of Medicine, 2002)

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 (1 2 8).  It is important that you increase high fibre foods gradually to give your body a chance to adjust (2). If you are feeling concerned, discuss what fibre levels are right for you with your dietitian.

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. You can also reduce the amount of insoluble fibre you consume by peeling your fruit and vegetables and by using processed grains (like white rice) instead of whole grains (like brown rice).

Can Fibre supplements be used on the Low FODMAP diet?

Rice bran and oat bran are low FODMAP fibre supplements that can be used on the Low FODMAP diet (8). 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 (10). Dr Jane Varney, from Monash University, recommends choosing a fibre supplement made from sterculia (3). 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 (3). FODMAP trained dietitian, Kate Watson, also recommends Citrucel as a fibre supplement because it is non fermentable and causes less bloating and gas (Source: personal communication, 29 August 2015).

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 (4 6). However, fibre supplements should be introduced slowly to allow the body to readjust and to reduce the possibility of aggravating IBS symptoms (6).

Avoid using fibre supplements that contain wheat bran, All Bran, inulin and chicory root as these are high FODMAP ingredients (8). Also check that fibre supplements do not contain high FODMAP sweeteners like sorbitol (10).

Check for Hidden High FODMAP Fibre Ingredients

Avoid fibre supplements and processed food products that contain chicory root or inulin as these are high FODMAP fibre sources.

Tips for Increasing Fibre Consumption

1. Aim to have seven servings of vegetables and fruit every day (11). This works out to be at least five serves of low FODMAP vegetables and two serves of low FODMAP fruit per day. Dr Jane Varney from Monash University recommends snacking on a wide range fruit like “ firm bananas, raspberries, rhubarb, kiwifruit, mandarin, strawberries, passionfruit and oranges” (3). Make sure you check the Monash University FODMAP Diet app for serving size information. Additionally, she suggests including a variety of vegetables in your meals, such as “carrot (skin on), green beans, potato (skin on), corn, silverbeet and eggplant (skin on)” to help increase fibre intake (3).
2. Aim to have four to six servings of whole grain products per day (11). This could include, quinoa, brown rice, oats (in limited amounts), gluten free breads and cereals. When selecting low FODMAP bread and cereals, compare the labels and choose brands with higher fibre levels (3).
3. Add toasted nuts, chia seeds, sesame seeds, sunflower or pumpkin seeds to salads, pasta dishes, and cereals like quinoa porridge (11).
4. Add safe serving sizes of canned chickpeas and lentils to salads and casseroles (3). A low FODMAP serving size of canned chickpeas is 1/4 cup and the safe serving size of canned lentils is 1/4 cup (3). Make sure you rinse the canned chickpea/lentils well before using to reduce the FODMAP content (3).

What low FODMAP foods are good sources of fibre?

(Source: Dietitians of Canada, 2013; Monash University App, 2014; Palmer, 2008; USDA, 2015)

What low FODMAP foods are high in soluble fibre?

The serving sizes listed in the table are the serving sizes that were tested for fibre content and may not be low FODMAP.  Please, make sure you only eat the low FODMAP serving sizes recommended in the Monash Low FODMAP app.

(Information sourced from Prebiotin, 2015)

What low FODMAP foods are high in insoluble fibre?

The serving sizes listed in the table are the serving sizes that were tested for fibre content and may not be low FODMAP.  Please, make sure you only eat the low FODMAP serving sizes recommended in the Monash Low FODMAP app.

(Information sourced from Prebiotin, 2015)

Final Thoughts

There are plenty of low FODMAP foods that are full of fibre, so try and get as much variety into your meals as possible. Happy cooking everyone!