What the AIP diet asks you to remove, what the small studies behind it actually found, and the two claims we have taken off this page.
The AIP diet, short for autoimmune protocol, is a time-limited elimination diet. You remove a long list of foods for about six weeks, hold that line for another five, then add foods back one at a time to see which ones you react to.
It is used by people with autoimmune conditions, and there is real research behind it. There is less than the internet suggests. This page has been rewritten to say exactly how much, because two of the claims that used to be here were not supported, and one of them concerned celiac disease.
Key Takeaways
- All the published trials are small and uncontrolled; none is randomised (1, 2, 3).
- In Hashimoto’s, symptoms improved but thyroid function and antibodies did not (3).
- Get tested for celiac disease before removing gluten, not after (6).
- It is a diagnostic tool with an end date, not a permanent diet (5).
- It does not replace treatment for an autoimmune condition (8).
What It Involves
Autoimmune disease is what happens when the immune system attacks the body’s own healthy tissue, and it covers a wide range of conditions with different treatments (8).
The protocol removes grains, legumes, dairy, eggs, nuts, seeds, nightshade vegetables, alcohol, coffee, refined sugars and food additives, leaving meat, fish, most vegetables, fruit, and a few oils. It is stricter than paleo eating, which allows nuts, seeds and eggs.
The reasoning is that these foods may provoke immune responses in susceptible people, and that removing them and then reintroducing them one by one reveals which ones matter for you. A 2025 review describes it as a personalised elimination approach aimed at symptoms and quality of life, and appraises it critically rather than promoting it (5).
The Three Phases
Save- Elimination, about six weeks in the studied version. Everything on the list comes out (1).
- Maintenance, about five weeks. You hold the same diet and see whether anything settles (1).
- Reintroduction. One food at a time, in small amounts, with a few days between each, recording what happens.
The third phase is the point of the whole exercise, and it is the one people skip. An elimination diet that never ends is not a diagnostic tool, it is just a very narrow diet, and the narrowness is where the nutritional risk sits.
What the Research Actually Found
Save| Condition | What the actual study was | How far it goes |
|---|---|---|
| Inflammatory bowel disease | An uncontrolled trial in 15 adults with active Crohn’s disease or ulcerative colitis. Disease activity scores fell substantially over 6 weeks of elimination and 5 weeks of maintenance, and faecal calprotectin dropped, though C-reactive protein did not change significantly. The authors wrote that randomised controlled trials are warranted (1) | Encouraging, not proven |
| Quality of life in IBD | The same small cohort reported significantly better quality-of-life scores as early as week 3, along with fewer bowel movements and less stress. Again uncontrolled, and the authors asked for larger randomised trials (2) | Encouraging, not proven |
| Hashimoto’s thyroiditis | A 10-week pilot in 16 women combined the diet with online health coaching. Quality of life and symptom scores improved and hs-CRP fell, but there were no significant changes in any thyroid function test or in thyroid antibodies (3) | Symptoms only |
| Rheumatoid arthritis | There is no trial of this diet in rheumatoid arthritis. A Cochrane review of 15 trials of dietary manipulation found the effects still uncertain, with higher drop-out and significant weight loss in the diet groups (4) | Not shown |
| Blood sugar and blood fats | The source previously cited here was a journal article we could not verify. We have removed the claim rather than repeat it (5) | Claim removed |
| Celiac disease | Cutting grains is not a treatment for celiac disease, and going gluten-free before testing makes the diagnosis harder to reach (6, 7) | Claim removed |
The IBD studies, in proportion
This is the strongest evidence the diet has, and it is worth stating precisely because it is usually reported as more than it is.
Fifteen adults with active Crohn’s disease or ulcerative colitis followed the protocol for six weeks of elimination and five of maintenance. Mean partial Mayo score fell from 5.8 to 1.0 in ulcerative colitis and mean Harvey-Bradshaw index from 7 to 3.4 in Crohn’s disease. Faecal calprotectin fell from 471 to 112, although that change did not reach statistical significance, and C-reactive protein did not change (1). Quality-of-life scores in the same cohort improved significantly by week 3 (2).
Those are real improvements in real patients. What the study cannot tell you is whether the diet caused them, because there was no control group, nearly half the participants were on biologic therapy, and the authors themselves concluded that randomised controlled trials are warranted (1).
Hashimoto’s: what did and did not change
The earlier version of this page said the diet appeared to slow damage to the thyroid. The study it refers to found the opposite of that.
Sixteen women with Hashimoto’s thyroiditis completed a 10-week programme combining the diet with online health coaching. Health-related quality of life improved on all eight subscales of the SF-36, symptom burden fell sharply, and hs-CRP decreased. But there were no statistically significant changes in TSH, free or total T4, free or total T3, or in thyroid peroxidase and anti-thyroglobulin antibodies (3).
Feeling better matters. It is not the same as the disease process slowing, and the page should not have said that it was. Note too that there was no control group and the diet came bundled with ten weeks of coaching, which is its own intervention.
Rheumatoid arthritis
No trial has tested this specific protocol in rheumatoid arthritis. The broader question of diet in RA was examined by a Cochrane review of 14 randomised trials and one controlled trial covering 837 patients, which found the effects of vegetarian, Mediterranean, elemental and elimination diets still uncertain, with studies small and at moderate to high risk of bias. Drop-out was about 10% higher in the diet groups, and participants lost significantly more weight (4).
Unintended weight loss is listed there as a harm, not a benefit, which is the right way to read it for anyone already underweight or unwell.
The Celiac Correction
The previous version of this page suggested that cutting grains eases the symptoms of celiac disease. We have removed it, because the framing is actively unhelpful.
NIDDK is explicit: doctors do not recommend starting a gluten-free diet before diagnostic testing, because a gluten-free diet affects the test results (6). European guidelines say the same, that serology and biopsy should be performed on a gluten-containing diet (7). Someone who reads a diet article, removes gluten, feels better and never gets tested has made their own diagnosis harder to obtain for months.
And if celiac disease is confirmed, the treatment is a strict, lifelong gluten-free diet with education and follow-up (7). That is a medical diagnosis with a defined treatment, not a food group you experiment with.
The Nightshade Question
Cutting tomatoes, peppers, aubergine and potatoes is one of the features that distinguishes this protocol from paleo, and it is also the part with the least behind it.
There is no trial showing that nightshades worsen autoimmune disease. A randomised trial of a nightshade elimination diet in rheumatoid arthritis has been registered and published as a protocol (9), which is exactly the signal that the question has not yet been answered. Reintroducing them properly in phase three is therefore worth doing rather than assuming they are out for good.
Who Should Be Careful
- Anyone with a history of disordered eating. A long forbidden-foods list and close symptom monitoring is a difficult combination.
- Anyone underweight or losing weight unintentionally. Diet trials in rheumatoid arthritis showed significantly greater weight loss in the intervention groups (4).
- Anyone not yet tested for celiac disease. Test first (6).
- Children, pregnancy and breastfeeding. Requirements are higher and the margin for error is smaller.
- Anyone on treatment for an autoimmune condition. This sits alongside that treatment, never instead of it (8).
Removing grains, legumes, dairy, eggs, nuts and seeds at once takes out most of the usual sources of calcium, fibre and several B vitamins. That is manageable with a dietitian and hard to manage without one.
Where It Fits
If your symptoms are digestive rather than systemic, the low FODMAP diet has considerably more trial evidence behind it and is also structured as a temporary elimination with reintroduction. Our elimination diet guide covers the general method, the paleo guide covers the less restrictive version, and the arthritis diet guide covers what has been tested for joint symptoms specifically.
Frequently Asked Questions
Does the AIP diet work?
For symptoms in inflammatory bowel disease there are two small uncontrolled studies with promising results, in a total of 15 patients. There is no randomised controlled trial of it in any condition. That is the honest state of the evidence: worth trying with support, not established.
Does it help Hashimoto’s thyroiditis?
A 10-week pilot in 16 women found better quality of life and fewer symptoms, but no significant change in any measure of thyroid function or in thyroid antibodies. The diet was delivered alongside a coaching programme and there was no control group, so some of the improvement may come from the support rather than the food.
Is it safe if I might have celiac disease?
Get tested first. Testing for celiac disease has to be done while you are still eating gluten, and starting a gluten-free diet beforehand can make the results unreliable. If celiac disease is confirmed, the treatment is a strict lifelong gluten-free diet, which is a different thing from this protocol.
How long does it last?
The studied version ran six weeks of elimination followed by five weeks of maintenance, then reintroduction. It is designed as a time-limited diagnostic exercise, not a permanent way of eating. If you are still eliminating everything months later, something has gone wrong.
Should I cut out nightshades?
There is no trial evidence that nightshades worsen autoimmune disease. A randomised trial of nightshade elimination in rheumatoid arthritis has been registered, which tells you the question is still open rather than settled.
The Bottom Line
The AIP diet is a structured, time-limited elimination diet with genuinely interesting early results in inflammatory bowel disease: two small uncontrolled studies in the same 15 patients, whose authors both called for randomised trials. In Hashimoto’s, the pilot that is usually cited found better symptoms and quality of life but no change in thyroid function or antibodies, and it is not honest to report that as the disease slowing. There is no trial of it in rheumatoid arthritis, and it is not a treatment for celiac disease, which has to be tested for before gluten comes out. If you try it, treat it as an eleven-week experiment with a reintroduction phase, run it with a dietitian, and keep taking your medication.
This article is for informational purposes only and is not a substitute for professional medical advice. Talk with your doctor or a registered dietitian before starting a restrictive elimination diet, and do not stop or change treatment for an autoimmune condition without medical advice.
Related Articles
Paleo Diet Plan Benefits, Foods, and Risks
FODMAP Diet: The 3 Steps and the List Errors
Arthritis Diet: Foods That Help, Foods to Limit and Evidence
Elimination Diet: How to Do It and What to Ignore