AIP Diet: Foods, Phases and What the Evidence Shows

The AIP, or autoimmune protocol, is a short-term elimination diet that removes a long list of foods, then adds them back one at a time to find out which ones trigger your symptoms. The evidence for it is early: it comes from small studies without control groups, so it is best seen as a structured way to test your own triggers with a clinician, not a proven treatment.

This guide covers the foods removed and allowed, how the phases work, what the studies in inflammatory bowel disease (IBD) and Hashimoto's thyroiditis found and did not find, and who should be careful. It is educational and does not replace advice from your doctor or a registered dietitian.

What is the AIP diet?

The GI Nutrition Foundation describes the AIP as having an elimination phase, a reintroduction phase and a maintenance phase. Unlike many therapeutic diets, it emphasizes and encourages adding tolerated foods back, to reach a healthy variety of foods you can eat. The elimination phase is described as a minimum of 30 days, and it may need to be longer.

Foods removed and foods allowed

During elimination, the GI Nutrition Foundation lists these as removed:

• Grains and legumes
• Nightshade vegetables
• Dairy and eggs
• Nuts and seeds
• Sugar
• Alcohol and coffee
• Processed foods and industrial seed oils

Foods that are encouraged include fish and seafood, poultry, unprocessed red meat (with grass-fed organ meats recommended), non-starchy vegetables, fruit in moderation, honey, and sweeteners such as date sugar and maple syrup. If you want background on the oil part of the list, see our guide to seed oils.

How reintroduction works

After the elimination phase, foods are tested one at a time while you watch for symptoms. Foods you tolerate are added back for good, and foods that cause symptoms stay out for now. The goal of the final maintenance phase is a diet built around the foods you personally tolerate, and the aim is variety, not permanent restriction.

What the studies found

Inflammatory bowel disease

An uncontrolled single-center trial enrolled adults with IBD and followed 15 of them (9 with Crohn's disease and 6 with ulcerative colitis) through a 6-week elimination phase and a 5-week maintenance phase. It reported that 73% reached clinical remission by week 6 and stayed in remission through the maintenance phase. The authors acknowledged a very small sample, no control group, and possible confounders such as lifestyle changes, medications and the natural course of the disease.

Hashimoto's thyroiditis

A 10-week pilot study of 17 women with Hashimoto's thyroiditis (16 completed it) combined the AIP with online coaching on sleep, stress, movement and time outdoors. Quality of life improved on all eight SF-36 measures, and average scores on a medical symptoms questionnaire dropped from 92 to 29. There were no statistically significant changes in TSH, T3, T4 or thyroid antibodies, and a marker of inflammation, hs-CRP, fell by 29%. The authors noted the small sample, the lack of a control group, the lack of blinding, and that the multi-part program made it hard to tell which element helped.

Taken together, these are promising signals in small studies, and neither shows that the diet itself caused the improvement. Larger controlled studies would be needed to say whether the AIP works better than other approaches.

Who should be careful

The AIP removes many food groups at once, which can make it harder to get enough nutrients, so it is best started with a doctor or registered dietitian. The GI Nutrition Foundation stresses that its guidance is not a guide to doing the diet alone, that the right starting point depends on symptom severity, and that the diet is a tool for conversations between patients and their clinicians. Talk to your care team first, especially if you are pregnant, have a history of disordered eating, take medicines that need to be taken with food, or are choosing it for a child.

Checking labels while you eliminate

Packaged foods hide many of the ingredients on the removed list, including seed oils, added sugars, gluten-containing grains, and spices or additives derived from nightshades such as peppers. Reading every ingredient list by hand is tiring.

Foodsage lets you choose conditions and your own sensitivities during setup, such as nightshade, gluten and soy, plus clean-eating avoid lists such as industrial seed oils, added sugars and gluten-containing grains. When you scan a product, it checks the ingredients against your choices and shows which ones matched. It is not an AIP program, and it does not replace guidance from your dietitian. For ingredient-by-ingredient references, see our guides for IBD and Hashimoto's, and our related guides on foods to avoid with IBS and the lupus diet.

Foodsage and the other MetricPoint apps are educational tools, not medical devices or medical advice. For decisions about your health, allergies, or a specific condition, talk to a qualified doctor or registered dietitian.