Low FODMAP reintroduction, explained
General information, not health advice. Talk to your doctor or dietitian about your own symptoms.
What reintroduction is for, and why it is done with a dietitian.
Last updated 2026-10-31 ยท By Torstein Skulbru
The short version
FODMAPs are groups of fermentable carbohydrates. A low FODMAP diet restricts them, and reintroduction is the later step where groups are tested back in, one at a time, to see which ones cause symptoms and in what amounts. It is done with a dietitian.
Where this fits
In UK guidance (NICE), a low FODMAP diet is an option when IBS symptoms continue after general diet and lifestyle advice, and it should only be given by a healthcare professional with expertise in dietary management. The British Dietetic Association suggests asking your doctor for a referral to a dietitian. The NHS notes that cutting foods out without advice can mean missing vitamins and minerals.
Why reintroduction exists
One NHS hospital leaflet says it is important to reintroduce FODMAPs even if symptoms have improved. It gives four reasons:
- To identify which groups of FODMAPs a person is sensitive to. Not everyone reacts to all of them.
- To identify the quantity that triggers symptoms. Small amounts may be well tolerated.
- To make the diet more varied and healthy.
- To keep gut bacteria healthy.
How it is done
Groups are tested back in one at a time, on a schedule set with your dietitian. This page leaves out the steps on purpose: they depend on your own situation and are not something to follow from a website.
Why a dietitian is involved
The leaflet says it should be used alongside advice from your dietitian. NICE says a low FODMAP diet should only be given by a healthcare professional with expertise in dietary management, and the British Dietetic Association suggests asking your doctor for a referral to a dietitian. If you are thinking about any of this, your doctor or dietitian is the person to ask.
Sources
- Gloucestershire Hospitals NHS Foundation Trust: Re-challenging after the low FODMAP approach (PDF). Why reintroduction is done. The leaflet says it should be used alongside advice from your dietitian.
- NICE guideline CG61: Irritable bowel syndrome in adults. A low FODMAP diet is an option when symptoms persist after general advice, and should only be given by a professional with expertise in dietary management.
- British Dietetic Association: IBS and diet. Suggests asking your doctor for a referral to a dietitian for a diet restricted in fermentable carbohydrates.
- NHS: Food intolerance. Foods should not be cut out without advice from a GP or dietitian, because vitamins and minerals can be missed.
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