Trigger foods: how they are looked for

What a food and symptom diary is

It is a running note of what you ate and drank, roughly when, and how you felt afterward. The NHS mentions keeping one for IBS, and says people may be asked to keep one when a food intolerance is being looked into. For an IBS appointment, the NHS says it might help to write down details of your symptoms beforehand.

What the NHS lists as possible triggers

For IBS, the NHS lists alcohol, caffeine, certain foods such as spicy or fatty food, stress and anxiety, and regular antibiotic use as things that can trigger a flare-up. It also says flare-ups can happen for no obvious reason.

Why one bad day says little

The NHS says food intolerance symptoms usually start a few hours after eating. Because flare-ups can also happen for no obvious reason, a single rough day is hard to read. A pattern across many days is a question to raise with your doctor or dietitian, not a conclusion.

How a professional looks into it

According to the NHS, a doctor may refer you to a dietitian. Tests can include a special diet where a suspected food is avoided, and after a few weeks it is eaten again to see whether symptoms return. NICE says single food avoidance and exclusion diets should only be given by a healthcare professional with expertise in dietary management.

The NHS says it is important not to cut foods out without the advice of a GP or dietitian, because you could miss out on vitamins and minerals.

When to see a doctor

• The NHS says to see a GP if you think you might have IBS and have had symptoms for over 4 weeks.
• The NHS also says to see a GP if diet changes are not helping, or if you need to avoid lots of different foods to control symptoms.
• The NHS says to ask for an urgent appointment if you have lost a lot of weight for no reason, have bleeding from your bottom, or find a hard lump or swelling in your tummy.