Bread bundles three separable suspects into every slice — wheat, gluten and baker’s yeast. Get a personalised shortlist of bread-related items worth exploring first, then work through them one at a time with a focused 6-week plan, instead of cutting everything and hoping.

What this screen is — and what it is not

What it is

• A screening tool to help you decide whether bread is worth exploring through a structured elimination diet
• A starting point for a focused 6-week elimination and reintroduction, which is what actually tells you about your own tolerance
• Based on a hair sample, with your report delivered within 3 days of your sample reaching our UK lab
• Non-invasive (just 9 or 10 strands of hair) and non-diagnostic
• A prompt to experiment carefully, not a verdict on what you must eat

What it is not

• A measurement of histamine, biogenic amines, FODMAPs or fructans, a hair test does not and cannot measure any of these
• A measurement of how your gut will react to bread, gluten or yeast in real time
• A diagnosis of coeliac disease, wheat allergy, gluten intolerance, or any medical condition
• A replacement for your GP’s testing (blood tests, gut biopsy, or allergy testing)
• A permanent answer or proof that you must avoid a food forever, it’s a tool to explore and experiment, not medical advice

Why Bread Triggers Discomfort: The Three Components

Bread isn’t a single food — it’s wheat flour, added yeast, and sometimes much more. You might get on badly with one component, two, or all three, and working out which spares you cutting out more than you need to.

Wheat and FODMAPs: wheat contains fructans, fermentable carbohydrates that gut bacteria turn into gas. For some people that means bloating within a couple of hours of a sandwich — nothing to do with gluten at all.

Gluten: the protein some people associate with bloating, stomach discomfort and tiredness (often described as non-coeliac gluten sensitivity — different from coeliac disease, which is a medical matter for your GP). Gluten is in wheat, barley and rye.

Yeast and amines: commercial bread is proofed for only an hour or two. During fermentation and storage, yeasted breads can develop biogenic amines such as histamine and tyramine, which some people seem to feel a few hours later.

Why sourdough is different: true sourdough fermented for 12–24 hours breaks down a good portion of the gluten and much of the FODMAP content. If sourdough suits you but regular sliced bread doesn’t, your sensitivity more likely sits with quickly fermented carbohydrates or gluten than with wheat itself.

One honest note: a hair screen can’t measure any of this happening in your body — no amines, no FODMAPs, no antibodies, no gut response. Your report is a prompt: a shortlist of bread-related items worth exploring first. Everything you actually learn about your own tolerance comes from removing them and reintroducing them one at a time — which is exactly what the 6-week plan is for.

Does this sound like you?

• Bloating or abdominal distension within 1 to 4 hours of eating bread
• Wind or gas after bread-based meals
• Stomach pain or cramping
• Loose stools or diarrhoea following bread
• Constipation
• Nausea or feeling full very quickly
• Foggy, tired or sluggish feeling after eating bread
• Mouth itching, throat irritation or tingling (especially with fresh bread)

Related foods worth checking at the same time

• Wheat and wheat-containing products (pasta, couscous, cereals, cakes)
• Other gluten-containing grains (barley, rye, and some oats depending on processing)
• Fermented foods often higher in amines, if amines from yeasted bread seem to be your trigger (aged cheese, cured meats, soy sauce, fermented condiments)
• FODMAP-rich foods like onions, garlic and apples, if fermentable carbohydrate sensitivity seems to be present
• Other yeasted products (beer, certain commercial sauces, and spreads made with baker’s yeast)

Examples of what the 700+ item panel covers

• Wheat
• Gluten
• Yeast (Baker’s)
• Barley
• Rye
• Spelt
• Kamut
• Oats

How to run a focused elimination

Plan for a 6-week core elimination plan, then optional component-by-component reintroduction.

1. Week 1: Remove all bread and wheat-containing products; carry on eating everything else as normal. Start your food diary on day one — the 90-day guarantee asks you to follow your plan for at least 6 weeks with a diary. (Feeling a bit off around days 3–5 is common as your gut adjusts.)
2. Week 2: If nothing has shifted, also remove other gluten-containing grains (barley, rye) and yeasted products (beer, some commercial sauces). Keep the diary short and daily.
3. Weeks 3–4: Continue the elimination. This is where many people notice change — less bloating, clearer-feeling thinking, easier digestion, steadier energy. Write down whatever you see, including nothing.
4. Weeks 5–6: Hold steady to the end of the core plan. If nothing has changed by week 6, bread may not be your trigger, or more than one food is involved — your report covers 700+ items, and a registered dietitian can help you take stock.
5. After week 6 (optional reintroduction): Test one component at a time — plain white bread one day, true sourdough a few days later, then a gluten-free loaf — eating a normal portion at breakfast and watching the next 24–48 hours. Two to three days between tests is what lets you tell wheat carbohydrates, gluten and yeast-related amines apart.

Reintroduce one possible trigger at a time, with 2 to 3 days’ rest between each test, so you can tell them apart. For example: Test 1 (Day 1) two slices of white bread at breakfast. Test 2 (Day 4) two slices of traditional sourdough. Test 3 (Day 7) a bowl of oats or a serving of barley. Note bloating, gas and any digestive changes as you go.

One customer’s experience

Nadia loved her morning toast until bloating and a foggy, sluggish feeling started arriving mid-morning. She assumed gluten was the culprit and went gluten-free for two months on her own — no difference, and no idea what to try next. Her IntoleranceLab report flagged bread-related items as worth a closer look, which was the nudge to stop guessing and run a structured 6-week elimination with a food diary instead. Working through reintroduction one component at a time afterwards, she found the problem didn’t behave like gluten or wheat itself: fast-proofed commercial bread brought the bloat back, while slowly fermented sourdough didn’t. It was the change in what she ate, not the screening, that made the difference — but the shortlist is what turned two months of random guessing into six focused weeks. She’s since brought other wheat foods back without cutting out more than she needs to.

Common questions

Is bread intolerance the same as coeliac disease?

No. Coeliac disease is an autoimmune disorder that only your GP can identify, using a blood test and a gut biopsy, and you need to be eating gluten regularly for those tests to be meaningful. In coeliac disease the immune system reacts to gluten and damages the small intestine, and it means avoiding gluten entirely for life. Bread intolerance or sensitivity doesn’t involve that autoimmune or allergic response, it’s more about feeling digestive discomfort after one or more components of bread — and people who simply feel sensitive to bread may get on fine with certain types, such as sourdough, or with specific grains. Our screening cannot rule coeliac disease in or out. If it’s on your mind, see your GP before changing your diet, because cutting out gluten beforehand can make the blood tests unreliable.

Why do some people get on with sourdough but not regular sliced bread?

Long fermentation changes the bread. Sourdough fermented for 12 to 24 hours goes through a process where wild yeast and bacteria break down a good portion of the gluten and reduce much of the fermentable carbohydrate (FODMAP) content. Regular sliced bread is usually proofed for only 1 to 2 hours, so gluten and FODMAPs are left largely intact. If you react to regular bread but get on with sourdough, your sensitivity is more likely to sit with quickly fermented wheat carbohydrates or gluten than with yeast itself. It isn’t a guarantee, which is why testing it yourself matters.

What’s the difference between wheat sensitivity and gluten sensitivity?

Wheat sensitivity means you react to something in wheat, which could be gluten, but could equally be fructans (a FODMAP), other proteins, or another compound. Gluten sensitivity (often called non-coeliac gluten sensitivity) means the gluten protein specifically is what bothers you. A careful elimination helps you tell them apart. If you react to regular wheat bread but get on with well-fermented sourdough, the issue is more likely carbohydrate-based than gluten. If you react to both, gluten may be involved. If you’re fine with wheat pasta but not wheat bread, the fermentation or another ingredient may be the factor.

Can a reaction to yeasted bread show up hours later?

It can. Yeast itself contains very little histamine, but yeasted breads can develop biogenic amines (such as histamine and tyramine) during fermentation and storage, more so when conditions are warm or dried yeast is used. Some people seem to react to these amines a few hours later, with digestive symptoms and tiredness, much like other intolerances. Fresh yeast tends to be lower, dried yeast higher. If your symptoms follow bread made with fresh yeast, the factor may not be yeast at all but the carbohydrates or other fermentation products. A hair screening can’t confirm any of this, it only flags foods to try, the elimination is what tells you.

How do I tell if it’s the bread or something in my sandwich?

Use the elimination process to isolate bread as a single variable. When you test bread, eat it plain or with something you’ve already confirmed is fine for you (like butter or a little salt). Eat it on its own at breakfast, then stick to foods you know suit you for the rest of the day. If you eat bread alongside cured meats, cheese and pickles all at once, you can’t tell which ingredient is behind it. Testing one thing at a time is what makes it clear.

Should I avoid all bread forever if it’s flagged in my screening?

Not necessarily. A screening points to foods worth exploring, it doesn’t mean you must avoid them forever. The aim is to use elimination and reintroduction to confirm which components actually affect you, then make informed choices. You might find you get on with sourdough but not regular bread, or heritage grains but not modern wheat, or bread without commercial yeast. Working through it carefully is how you avoid restricting more than you need to and keep enjoying the foods that suit you.

Related reading

• Gluten Intolerance Guide
• Histamine & Fermented Foods
• Dairy Sensitivity Explained
• Managing Bloating Symptoms
• Wheat Sensitivity Explained