Nutrition briefing
Challenging foods
After an elimination phase, reintroducing foods one at a time is how you find out which ones actually trouble you. Done carefully, the challenge gives a clear answer. Done too soon, it only muddies the result.
How to do the challenges
Choose a pure form of the food
Reintroduce the food in its simplest form so nothing else clouds the result. For example: wheat as VitaBrits or pasta, barley as pearl barley, rye as rolled rye, oats as rolled oats, dairy as plain milk with nothing added, cocoa as plain cocoa powder.
Start at breakfast
On a day you have chosen for the challenge (ideally not a working day), eat the selected food as the first thing in your breakfast. If you get symptoms, stop. You are probably sensitive to this food.
Build up across the day
If you get no symptoms after breakfast, include the food at lunch and dinner as well. As before, stop at any point if symptoms appear.
Continue for three days
If you still feel fine the next day, keep the food in your diet at breakfast, lunch, and dinner for another two days (three days in total). Gut and breathing symptoms can come on very quickly, but skin changes can take a few days to surface.
Clear after a week, then move on
If you are still well after a week, it is fine to keep this food in your diet. You can then choose the next food to challenge using the same process.
Watch for the processed-food difference
You may feel fine on the simple pure form but unwell on the same food in processed products. Keep a record. The culprit may be preservatives, colours, or yeast rather than the food itself. Many people tolerate pure wheat but react to bread, where the trigger is one of the many bread additives.
Subtle and delayed signs
Important safety note
Frequently asked questions
How do you reintroduce foods after an elimination diet?
Foods are reintroduced one at a time, in their purest form, and only once you are completely well and symptom-free. The approach is to test a single food at breakfast, and if there is no reaction, include it at lunch and dinner, continuing for three days, then leaving about a week clear before the next food. Using simple, unprocessed forms, for example wheat as plain pasta or dairy as plain milk, keeps the test clean and the result clear.
What symptoms should I watch for when challenging a food?
Watch for more than just obvious physical symptoms. Subtle signs can include cravings, and changes in mood or behaviour, alongside digestive or skin reactions. The symptom window can also be delayed, with skin changes sometimes taking a few days to appear, which is why each food is tested over three days with a clear gap before the next. Keeping notes helps you spot patterns you might otherwise miss.
Is it safe to reintroduce foods that caused a severe reaction?
No. Foods that have previously caused anaphylaxis or a severe allergic reaction should not be challenged at home. This food-reintroduction process is intended for identifying milder intolerances after an elimination diet, not for testing serious allergies. Any reintroduction of a food linked to a severe reaction must be done under appropriate medical supervision, not as part of a home challenge.
Reviewed by Rohan Smith, BHSc Nutritional Medicine · Elemental Health & Nutrition, Adelaide. Last reviewed 13 June 2026.
Important: This summary is general information, not personalised medical advice, diagnosis, or a treatment protocol. Speak with a qualified practitioner about your individual situation. Book a consultation →