Sweetcorn is easy to spot. Cornstarch, corn syrup, maltodextrin and dextrose aren’t — they’re tucked into sauces, snacks and ‘modified starch’ on half the labels in your kitchen. Our £49 hair screen covers corn and corn-derived items among 700+ items and gives you a shortlist of foods worth exploring first, so your elimination is systematic instead of guesswork. Report within 3 days of your sample arriving at our UK lab.
What this screen is — and what it is not
What it is
A hair-based screen covering 700+ items — including corn, cornstarch, corn oil, maltodextrin, dextrose, corn syrup and other corn-derived ingredients
A shortlist of foods worth exploring first, so your elimination and reintroduction is systematic instead of guesswork
Non-invasive — 9 or 10 strands of hair, posted to our UK lab, with your report within 3 days of your sample arriving
Most useful when paired with careful label-reading and an honest food-and-symptom diary, kept from day one
Backed by our 90-day money-back guarantee — follow your 6-week elimination plan, keep a food diary, and if your symptoms haven’t improved we’ll refund you in full
What it is not
A medical diagnosis, and not a test for coeliac disease, a corn allergy, or any medical condition
A measurement of your digestion — it doesn’t watch how your gut handles corn, and what you actually learn comes from removing corn, reintroducing it, and noting how you feel in your diary
A replacement for seeing your GP if you have severe symptoms, bleeding, unexplained weight loss, or symptoms that get worse despite changing your diet
A cure or treatment for anything
Proof that corn is ‘bad’ for everyone — plenty of people get on with corn perfectly well
A quick fix: the 6-week core plan asks for patience and consistent record-keeping — which is also exactly what our guarantee asks for
Why Corn Can Trigger Digestive Symptoms
Corn intolerance is the term people use when the digestive system seems to struggle with corn, whether that’s the proteins or some of the carbohydrates it contains. Parts of corn that aren’t fully absorbed in the small intestine can ferment further down in the large intestine, and that fermentation produces gas, which some people feel as bloating or wind. Sweetcorn in particular contains a sugar alcohol called sorbitol plus a good amount of fibre, both of which can be fermented. This is different from a corn allergy, which involves the immune system, and from coeliac disease or lactose intolerance, which have recognised medical tests. A corn sensitivity isn’t something any test — ours included — can pin down for you; the honest way to explore it is to remove corn for a while, watch whether your symptoms settle, then reintroduce it and see whether they return. Where our hair screen fits is the starting point: it screens your sample across 700+ items — including corn, cornstarch, corn oil, maltodextrin, dextrose and corn syrup — and your report gives you a shortlist of foods worth exploring first, so you’re not eliminating at random. One pattern worth knowing about: people sometimes find they’re fine with fresh corn but notice problems with processed foods. That isn’t because plain cornstarch is somehow more potent — cornstarch is almost pure starch, and refining strips out most of the fibre and fermentable sugars. A reaction to processed foods is more often down to other corn-derived ingredients (such as corn syrup or maltodextrin), the wider recipe, or simply how much you’ve eaten. Your diary is what untangles which of these matters for you.
Does this sound like you?
Bloating or a feeling of fullness after eating corn or corn-based foods
More wind or flatulence than usual
Abdominal discomfort, cramping, or a gripey, spasmodic pain
Looser stools or constipation
Nausea or feeling overfull too quickly
Symptoms tending to appear a few hours after eating corn
Symptoms easing when corn is removed for two to three weeks
Symptoms returning when corn is reintroduced
Related foods worth checking at the same time
Wheat and other cereal grains — some people who notice corn also notice patterns with related grains
Sorghum, a closely related grass grain that sometimes turns up in the same patterns
Barley or rye, worth watching in your diary if grains seem to be a theme for you
Peach and other stone fruits — relevant only for the minority sensitive to plant lipid transfer proteins (LTPs), and worth noting separately rather than assuming a corn link
Other high-fibre or higher-FODMAP plant foods, which can produce similar bloating and wind and be easy to confuse with corn — your diary helps tell them apart
Examples of what the 700+ item panel covers
Corn
Cornmeal
Cornstarch
Corn oil
Corn silk
Popcorn
Sweetcorn
Polenta
Maltodextrin (corn-derived)
Dextrose (corn-derived)
Corn syrup
High-fructose corn syrup
Modified food starch
How to run a focused elimination
Plan for 6 weeks of core elimination, then structured reintroduction one form of corn at a time.
Week 1–4: Remove corn and corn-derived ingredients: corn, cornmeal, cornstarch, corn oil, maltodextrin, dextrose, corn syrup, high-fructose corn syrup and ‘modified food starch’ (which is often corn). Read labels on sauces, dressings, processed meats, baking powder and packaged snacks — the ‘Where does corn hide in food?’ question below lists the trickier E-numbers if you want to go deeper. Start your food and symptom diary on day one.
Week 5–6: Give things time to settle and keep the diary going. Many people notice bloating or wind easing within the first week or two, but a gut that’s been unsettled for a long time needs the full six weeks to calm properly — and a clean baseline is what makes your reintroduction readable.
After week 6 — first test: Pick your first reintroduction food. Start with fresh corn (corn on the cob, sweetcorn, or polenta), since it’s closest to the whole food. Eat a normal-sized portion and watch how you feel over the next 48–72 hours. Log everything: what you ate, the portion size, and any symptoms.
Next: If fresh corn was fine, wait three clear days, then try a different form — cornstarch, corn oil, or a processed food containing corn syrup. Again, observe for 48–72 hours and log what happens.
Carry on through your shortlist one food at a time, three to four days apart. If a food brings symptoms back, wait until they’ve fully cleared before testing the next one. If corn in some form lines up with your symptoms, your diary has found your likely trigger; if nothing does, corn looks fine for you — and you can explore the next foods on your report instead.
Reintroduction is where the picture comes together. If removing corn for six weeks settles your symptoms, and bringing it back lines up with bloating or wind returning, that’s a strong personal signal — confirmation through your own response, recorded in your own diary. Some people find fresh corn sits fine but a particular corn-derived ingredient doesn’t; others find all forms are best limited. Reintroduction can take a few more weeks to map fully, and that’s normal. The 90-day guarantee asks you to follow your plan for at least 6 weeks with a food diary — start your diary on day one. By the end you’ll have a clear, written map of which foods and forms work for your body.
One customer’s experience
Greg, a 42-year-old IT manager, had been getting bloating and cramping after lunch for over a year. His GP ran the usual checks and everything came back normal, which left him feeling stuck — and guessing. His IntoleranceLab report flagged corn-derived ingredients among the items worth exploring first, which is where he started: a 6-week elimination of corn in all its forms, with a daily food and symptom diary from day one. Over the first couple of weeks his bloating eased noticeably. During the careful reintroduction that followed, sweetcorn on the cob didn’t seem to bother him, while several processed foods made with corn-derived ingredients lined up with his worst afternoons. He now reads labels with confidence and feels he understands his digestion far better. Greg’s pattern is his own; the point of the process is to help you map yours — the report tells you where to start, and the diary does the real work.
Common questions
Where does corn hide in food?
Corn turns up all over processed food, sometimes under its own name and sometimes not. Things to look for: cornstarch and ‘modified food starch’ (thickeners in sauces, soups, custards and gravies — modified starches often appear as E1404–E1450 on labels), corn syrup and high-fructose corn syrup (sweeteners in soft drinks, condiments, confectionery and some low-fat snacks), maltodextrin (a bulking agent in protein powders, instant foods and supplements), dextrose and glucose syrup (sweeteners and anti-caking agents, usually corn-derived), corn oil (cooking oil, salad dressings, baked goods) and ‘natural flavours’ (which can include corn-derived compounds). Even everyday additives such as citric acid (E330) and xanthan gum (E415) are often produced from corn glucose — most people are fine with these highly refined forms, but they’re worth knowing about if you’re being thorough. Corn also crops up in tinned vegetables, processed meats, instant noodles and some vitamins and medicines. Reading labels carefully is the single most useful habit — and your report’s shortlist tells you which foods to scrutinise first.
How does the IntoleranceLab screen actually help with corn?
Honestly: it gives you the starting point, not the verdict. Your £49 Gold screen checks your hair sample across 700+ items — including corn, cornstarch, corn oil, maltodextrin, dextrose and corn syrup — and your report lists the items worth exploring first. No hair screen can tell you that corn is definitely your trigger; what yours does is turn ‘it could be anything’ into a focused shortlist, so your six weeks of elimination are spent testing the likeliest candidates instead of guessing. Any improvement you notice comes from the elimination process you follow — the report is the map, not the journey.
Is corn intolerance the same as a corn allergy?
No. A corn allergy involves the immune system and can cause severe, fast reactions such as swelling, hives, breathing problems or anaphylaxis. A corn sensitivity is a digestive thing — your gut seems to struggle with corn, and you might notice bloating, wind, cramping or changes in your bowel habits a few hours later. You can explore a corn sensitivity through elimination and reintroduction at home. A suspected corn allergy is different: that needs proper testing arranged by your GP or an allergy specialist, and you should never deliberately reintroduce a suspected allergen without medical supervision.
Can I react to cornstarch but not fresh corn?
Some people do notice this pattern, though the reason is often misunderstood. It usually isn’t because cornstarch is somehow stronger — cornstarch is almost pure starch, and refining removes most of the fibre and fermentable sugars, so plain cornstarch tends to be low in fermentable carbohydrates. If a processed food made with corn upsets you while sweetcorn on the cob doesn’t, the more likely explanation is the other ingredients in that food (corn syrup, additives, fat, or simply the portion size) rather than the cornstarch itself. This is exactly why systematic reintroduction is worth the effort: testing fresh corn first, then individual processed forms, helps you see what your body is actually responding to.
How long before I notice a difference after removing corn?
Many people notice bloating or wind easing within the first week or two of removing corn. If your symptoms have been going on for a long time, your gut can take longer to settle fully, which is why the core elimination runs to six weeks — it gives things time to calm down properly. Keep your food diary throughout; small early improvements often help you stick with it. If you’ve seen no change by week three or four, corn may simply not be your trigger — keep going to the end of the plan for a clean baseline, then turn your attention to the other foods on your report shortlist.
What if I react during reintroduction?
Stop eating that food. Wait until your symptoms have fully cleared — usually 48–72 hours — before testing the next one. Your diary will point to which food was involved. If fresh corn brought symptoms back, leave at least four clear days before testing cornstarch, so there’s a clean gap between tests and no confusion about what caused what. If every form of corn seems to line up with symptoms, corn looks like a consistent trigger for you, and you can decide whether to leave it out for now or keep your intake small and occasional.
Can I ever eat corn again if it seems to be a trigger?
Possibly — reintroduction is about finding out what’s workable for you, not slamming a door. If corn lined up with symptoms, you can revisit it in a few months to see whether things have changed. Some people notice corn only seems to bother them when they’re run-down or eating a lot of processed food at the same time. Others find they’re fine with small, occasional amounts, and a few decide it’s easier left out. Your diary is your guide. By the end of your elimination and reintroduction you should have a clear sense of whether corn is best avoided or something you can manage in certain forms or amounts.
Should I avoid corn if the elimination shows it isn’t a trigger?
No. If your elimination and reintroduction show corn doesn’t drive your symptoms, there’s no reason to cut it out. Corn is a nutritious food and most people get on with it fine. The whole point of the process is to remove foods only when your own results clearly point to them. Cutting out foods you don’t need to avoid just narrows your diet and makes mealtimes harder than they need to be.
Can a corn sensitivity cause symptoms beyond bloating and gas?
Most of what people notice with corn is digestive: bloating, wind, cramping, and changes in bowel habits. Some people also report feeling tired or getting headaches that seem to ease when they remove corn, but those are far less common and have many possible causes, so it’s wise not to jump to conclusions. The most useful thing is to track digestive symptoms and your energy in your diary. If a genuine pattern shows up — say, tiredness that reliably follows sweetcorn — write it down. The diary is what separates a real pattern from a coincidence.
What’s the difference between FODMAP sensitivity and a corn sensitivity?
Sweetcorn contains some fermentable carbohydrates — mainly the polyol sorbitol, plus fibre — which can cause bloating and wind in people who are sensitive to FODMAPs. That’s one reason corn bothers some people. Some are sensitive to FODMAPs across the board; others react mainly to corn. If removing corn helps but you still struggle with foods like onions, garlic, wheat or beans, you may have a broader FODMAP sensitivity worth exploring — your report covers those items too, and your diary will show the pattern. Worth knowing: plain cornstarch is typically lower in FODMAPs than whole sweetcorn, so if you’re fine with cornstarch but not fresh corn, FODMAPs may well be part of the story for you.
When to speak to your GP. This screen is for self-exploration and dietary guidance only — it is not a medical diagnosis, and it cannot test for coeliac disease, lactose intolerance, or a corn allergy, which all need proper testing arranged through your GP. If you have severe or persistent digestive symptoms, unexplained weight loss, blood in your stool, or symptoms that get worse despite changing your diet, please see your GP first. If you think you may have a food allergy rather than a sensitivity — especially if you have a family history of allergies or have had rapid, severe reactions — talk to your GP about a referral for proper allergy testing.
