Food reaction tracker UK — the diary your GP actually wants
Last reviewed: 7 May 2026
A reaction tracker is a diary tool, not a diagnostic. We make logging meals and symptoms easy so you can take a clear, dated record into your next NHS appointment or dietitian consultation. We don't tell you a food is your trigger — that's a clinical call.
Get NutraSafe on the App StoreWhat a food reaction diary actually is
A food reaction diary, also called a food and symptom diary, is a dated record kept over days or weeks. It pairs four things: what you ate (at ingredient level where you can), the time you ate it, the symptoms you experienced afterwards, and when those symptoms started and stopped. The timing is what turns a list of meals into clinically useful evidence.
It's the first piece of evidence a UK GP, dietitian or specialist allergist will ask for if you describe recurrent symptoms you suspect are food-linked. Recall doesn't cut it — by the time you sit down with a clinician, last Wednesday's lunch has merged with the rest of the week. A dated diary moves the conversation from "I think dairy might bother me" to "in the last fortnight I logged six episodes of bloating, and five followed meals containing dairy". That's all a reaction tracker needs to do well: capture the what, the when and the symptom, and make logging quick enough that you keep doing it.
What you record
The meal at ingredient level, the time you ate, the symptoms, and when those symptoms started and stopped.
What it isn't
Not a diagnosis. Not a verdict on individual foods. Not a substitute for a GP appointment or a dietitian referral.
Why dated logs beat memory
Recurrent symptoms blur in retrospect. A timestamped record gives a clinician something to work from.
How long for
NHS and BDA guidance both lean on 7 to 14 days as the first window. Long enough to surface patterns, short enough to keep up with.
What the NHS and BDA actually ask for
If you've been to a GP about recurrent gut symptoms, headaches after meals, fatigue, or skin flares, you'll likely have heard a version of "keep a food diary first". Here's the structure clinicians work from in the UK.
NHS food intolerance guidance: a diary comes before elimination
The NHS page on food intolerance is explicit that the first step, if you suspect an intolerance, is to keep a record of what you eat and any symptoms you have. Removing foods on a hunch makes any later assessment harder — there's no baseline to compare against.
BDA food fact sheets: 7 to 14 days, ingredient-level
The British Dietetic Association's food fact sheets on IBS, food intolerance and elimination diets all describe the food and symptom diary as the foundation of a dietitian-led workup. The recommended detail level is the ingredients in each meal, plus the timing of symptoms — not just the meal name.
For suspected allergy: a specialist clinical workup
Suspected food allergy is a different pathway. NHS allergy clinics use skin prick testing, specific IgE blood tests and, where needed, supervised oral food challenges. A diary is helpful background but isn't itself diagnostic. If a reaction has ever involved breathing difficulty, lip or tongue swelling, or anaphylaxis-like symptoms, the route is urgent medical advice and a referral, not an app.
What patterns are useful, and what aren't
Single meals followed by a single symptom rarely move a clinical conversation. Patterns over time do — repeated near-simultaneous reactions to a recurring ingredient, or a clear absence of reactions when a food wasn't eaten. That's why a diary needs ingredient-level detail and a fortnight of data, not a snapshot.
Allergy, intolerance, sensitivity — and why an app can't diagnose any of them
These three words are used interchangeably in everyday speech, but in clinical use they mean different things. The honest version of what an app can and can't do depends on which one you're dealing with.
Food allergy (IgE-mediated)
An immune-system response. Symptoms appear within minutes to a couple of hours — hives, lip or tongue swelling, vomiting, and at the severe end anaphylaxis. Diagnosed by an allergy specialist using skin prick tests, specific IgE blood tests and, where needed, supervised oral food challenges. Not something an app can confirm.
Coeliac disease
An autoimmune condition triggered by gluten. Diagnosed by a GP blood test (tissue transglutaminase antibodies) plus, in most adults, a confirmatory gut biopsy. Keep eating gluten until tested — stopping beforehand invalidates the result.
Lactose intolerance
A digestive issue from low lactase activity. Diagnosed clinically from history plus a controlled trial of lactose reduction, sometimes with a hydrogen breath test. Symptoms tend to map onto dairy intake at quantity, which a diary captures cleanly.
Other intolerances and "sensitivities"
Most non-coeliac, non-lactose intolerances have no single diagnostic test. The clinical route is supervised elimination and reintroduction with a registered dietitian, using the food and symptom diary as the input. Direct-to-consumer "IgG food sensitivity tests" are not endorsed by the NHS, BDA or Allergy UK for diagnosing food intolerance.
What you log, and why it has to be ingredient-level
"Curry" isn't a diary entry. "Curry containing garlic, cumin, cream, ground almonds and onion" is. The reason matters.
When a clinician reads back through a diary, they're looking for ingredients that recur across meals followed by symptoms, and don't recur across meals that weren't. "Curry on Tuesday" and "stir-fry on Friday" hides that both meals contained garlic and onion. Listing ingredients makes the pattern legible.
Capturing ingredients by hand is where most paper diaries fall down. Our barcode scanner pulls ingredients from UK supermarket and own-brand catalogues (Tesco, Sainsbury's, Asda, Aldi, Lidl, Morrisons, M&S, Waitrose). Meals without a barcode — sandwich made on site, takeaway, home cooking — log manually with whatever detail you have.
Common reaction types you can record alongside meals
Each reaction takes severity (mild, moderate, severe), a start time and a free-text note. Custom symptoms are supported.
The Big 14 UK allergens, and why Natasha's Law matters here
UK food law (the Food Information Regulations 2014, retained post-Brexit) requires 14 named allergens to be emphasised on ingredient lists. If you're keeping a reaction diary, these are the names you'll most often want to scan for.
The Big 14 (Food Information Regulations 2014)
- Celery
- Cereals containing gluten (wheat, rye, barley, oats)
- Crustaceans
- Eggs
- Fish
- Lupin
- Milk
- Molluscs
- Mustard
- Peanuts
- Sesame
- Soybeans
- Sulphur dioxide and sulphites (above 10 mg/kg or 10 mg/L)
- Tree nuts (almonds, hazelnuts, walnuts, cashews, pecans, Brazil nuts, pistachios, macadamia)
Natasha's Law (October 2021)
Pre-packed for direct sale (PPDS) items — sandwiches made on site, salad bowls assembled at the counter, pastries finished at the bakery — must now carry a full ingredient list with the 14 named allergens emphasised. Before Natasha's Law these items often went out unlabelled, leaving on-the-go meals as a blank spot in any food diary.
What we record on our side
When you scan a UK retail product, we surface allergen warnings against the ingredient list we have on file (allergen warning detail is part of NutraSafe Pro). We won't tell you a product is allergen-free — ingredients change between batches, cross-contamination varies. The packaging on the item in your hand is the source of truth.
What we surface, and what we deliberately don't do
The honest line between "useful summary for a clinical conversation" and "a verdict the app shouldn't be making". We sit firmly on one side of it.
What suspected-triggers analysis does (Pro)
For Pro users, we show correlations across logged meals and reactions: "you logged a reaction within 3 hours of eating this ingredient four times in the last 30 days." A count, with timing, in plain English. We do the comb-through; not the interpretation.
What it isn't
Not a diagnosis. We don't say "this is your trigger" or attach a confidence score that invites people to treat it as a clinical readout. A correlation in a personal diary is suggestive, not causal — confounders include stress, sleep, illness and medications. A clinician weighs that.
Things we won't write
We won't tell you to remove a food. We won't recommend an elimination protocol. We won't label a product as allergen-free. We won't suggest your symptoms are or aren't a particular condition. Those calls belong to your GP, dietitian or specialist allergist.
What you take to your GP
Share or screenshot the diary view for your appointment. NHS GPs typically have ten minutes; a structured 7 to 14 day record of meals and symptoms with timing lets them make a more informed call about whether to refer on to a dietitian or allergy clinic.
Free vs NutraSafe Pro
Free covers logging up to 25 foods per day, barcode scanning with our processing grade, and your five most recent reactions visible. Pro is £3.99/month (monthly only, no annual tier) and unlocks full reaction history, suspected-triggers analysis, allergen warning detail on barcode scans, and processed-food and NRV insights.
Where we differ from "allergy apps"
Some apps in this category present close to a diagnostic — letter-grading individual foods, generating "your trigger profile" pages. We don't, on principle. The diary here is the same kind a registered dietitian would ask you to keep on paper. The interpretation belongs to the clinician.
Related reading
Build the reaction diary your GP can actually use
Log meals and reactions in NutraSafe and share them at your next appointment. Free to log up to 25 foods/day and 5 visible reactions · NutraSafe Pro £3.99/month for full reaction history, suspected-triggers analysis and allergen warning detail.
Get NutraSafe on the App StoreFrequently asked questions
What is a food reaction diary, and why do GPs ask for one?
A dated record of what you ate (ideally at ingredient level), meal timing, symptoms and symptom timing. NHS guidance on food intolerance and BDA food fact sheets both recommend keeping a 7 to 14 day diary before seeing a dietitian or attempting elimination. The patterns over time are what a clinician needs to interpret.
Can a food reaction tracker app diagnose a food allergy or intolerance?
No, and we don't try to. Food allergy is diagnosed by a specialist using skin prick testing, specific IgE blood tests or supervised oral food challenges. Most non-coeliac, non-lactose intolerances have no single diagnostic test — the route is supervised elimination and reintroduction with a registered dietitian. Coeliac disease is diagnosed by a GP blood test plus a confirmatory gut biopsy in most adults, and you should keep eating gluten until tested.
What does the suspected-triggers analysis actually do?
It surfaces correlations across your logged meals and reactions, in plain English: "you logged a reaction within 3 hours of eating this ingredient four times in the last 30 days." It does not call that ingredient your trigger. It surfaces the data your GP, dietitian or registered allergist can interpret. Part of NutraSafe Pro.
What is free, and what is in NutraSafe Pro?
Free covers logging up to 25 foods per day, barcode scanning with our processing grade, and your five most recent reactions visible (older entries blur). NutraSafe Pro is £3.99/month, monthly only with no annual tier, and unlocks full reaction history, suspected-triggers analysis, allergen warning detail on barcode scans, and processed-food and NRV insights.
How do I record meals from sandwich shops, bakeries and takeaways?
UK retail items scan via barcode against our supermarket and own-brand catalogues. Pre-packed for direct sale items — sandwich made on site, salad assembled at the counter, pastry finished at the bakery — carry a full ingredient list under Natasha's Law (October 2021) but no barcode, so we provide manual ingredient logging. Restaurant meals are logged at meal level with whatever detail the menu or kitchen shares.
Will the app tell me a product is allergen-free?
No. We surface allergen warnings against the ingredient list we have on file for a product, but we won't make a negative claim about a specific item. Ingredients change between batches and cross-contamination varies by manufacturing line. The packaging on the item in your hand is the source of truth.
Always read the label. We surface ingredients and allergens against the data we have on file for a product — but ingredients change between batches and cross-contamination varies by manufacturing line. The packaging on the item in your hand is the source of truth. We are a tracking tool. We don't replace medical advice from your GP, registered dietitian or specialist allergist.