Non-fermentable bulking agents (NFBAs)

What are NFBAs?

NFBAs are natural sources of fibre which can help to regulate bowel movements by softening and increasing the bulk of the stools. This makes them easier to pass and therefore can help to relieve or prevent constipation.

Why do I need to take a NFBA?

There are two main reasons that you may have been asked to take an NFBA:

1. To help manage symptoms of constipation
2. Whilst following a low fibre or low FODMAP diet

Dietary fibre is fermented by bacteria in your gut, producing gases which can lead to wind and bloating for some people. Following a low fibre diet can reduce these symptoms. However, decreasing dietary fibre can sometimes lead to constipation which the NFBA can help to prevent or treat. NFBA are not fermented by bacteria in your gut and therefore will not cause wind and bloating.

How long should I take a NFBA for?

The majority of people see benefits with linseeds for constipation within four weeks but the improvements can be very gradual. You should take a NFBA whilst you are following a low fibre diet. You should also continue to take a NFBA whilst you reintroduce fibre back into your diet although you may need to reduce the dose gradually as you introduce more fibre. It is safe to take NFBAs in the longer term as they are a natural source of fibre.

What types of NFBAs can I take?

There are three types of NFBAs which are suitable to take while following a low fibre diet. You only need to take one bulking agent at a time.

It is important that you take each dose of bulking agent with at least 300ml (1/2 pint) of non-caffeinated fluid such as water or squash or you may experience increased bloating, wind or constipation.

NFBAs can be taken either with or without food. Do not take bulking agents just before you go to bed.

1. Golden or cracked linseeds or flaxseeds

These are seeds from the flax plant which have had the outer husk removed. They can be milled or ground or taken as whole seeds. Sprinkled the seeds onto prepared foods such as breakfast cereals, yoghurt, salads or soups. Alternatively they can be placed on the tongue and swallowed immediately with water.

Dose - Initially, try taking one tablespoon twice a day, this can be split up into smaller doses spread out throughout the day if you cannot tolerate the whole dose at a time. If you are still experiencing constipation after a few days, try increasing the dose to two tablespoons twice a day.

2. Normacol (also known as sterculia)

Normacol granules are a vegetable gum from the karaya tree. They should be placed on the tongue and swallowed whole without chewing or crushing. Alternatively, they can be sprinkled over soft foods such as yoghurt or pureed fruit.

Dose - Initially, try one heaped 5ml teaspoon or one sachet twice a day after meals. If you are still experiencing constipation after a few days try increasing the dose by an extra 5ml teaspoon or one sachet per day. Please ask your dietitian about a suitable change in dose if you are unsure.

3. Celevac (also known as methylcellulose)

Celevac is a pink chewable tablet. It is recommended that the tablets should be broken in the mouth before swallowing. Celevac tablets swell in contact with water and should therefore be swallowed carefully.

Dose - Initially, try taking three tablets twice a day after meals. If you are still experiencing constipation after a few days, try increasing the dose to four tablets twice a day. Please ask your dietitian about a suitable change in dose if you are unsure.

Where can I get NFBAs from?

Celevac and Normacol are available to buy from pharmacies. Cracked and golden linseeds can be purchased from some larger supermarkets (in the baking section) and health foods stores.

Are NFBAs gluten and lactose free?

All NFBAs are gluten free. Normacol and linseeds are lactose free. Celevac contains lactose.

Where can I find more information?

Please contact your dietitian on 01223 216655 if you have any questions. Your local pharmacist and GP should also be able to provide more information.