The Autoimmune Protocol (AIP) diet is an elimination diet designed to reduce inflammation and alleviate symptoms in individuals with autoimmune disorders. This article provides a comprehensive overview of the AIP diet, its potential benefits and risks, and how it compares to other dietary approaches.
Introduction to Autoimmune Diseases and the AIP Diet
Autoimmune diseases occur when the immune system mistakenly attacks healthy tissues, leading to chronic inflammation and a variety of symptoms. Examples of autoimmune disorders include rheumatoid arthritis, psoriatic arthritis, multiple sclerosis, Sjögren's syndrome, celiac disease, lupus, Hashimoto’s disease, inflammatory bowel disease (IBD), and polycystic ovary syndrome (PCOS).
The AIP diet aims to mitigate symptoms and improve the quality of life for individuals with autoimmune conditions by focusing on gut health and identifying specific food triggers. It starts with an elimination phase, removing foods that may cause inflammation, and continues with a reintroduction phase to personalize a tailored diet plan.
How the AIP Diet Works
The AIP diet consists of three main phases: elimination, reintroduction, and maintenance.
1. Elimination Phase
The first phase involves removing foods and medications believed to cause gut inflammation, imbalances between levels of good and bad bacteria in the gut, or an immune response. During this phase, foods such as grains, legumes, nuts, seeds, nightshade vegetables, eggs, and dairy are completely avoided. Tobacco, alcohol, coffee, processed vegetable oils, refined and processed sugars, food additives, artificial sweeteners, and certain medications like non-steroidal anti-inflammatory drugs (NSAIDs) should also be avoided.
Read also: The Hoxsey Diet
NSAIDs include ibuprofen, naproxen, diclofenac, and high dose aspirin.
This phase encourages the consumption of fresh, nutrient-dense foods, minimally processed meat, fermented foods, and bone broth. Lifestyle factors such as stress, sleep, and physical activity are also emphasized. The elimination phase typically lasts for 30-90 days, but can be maintained until a noticeable reduction in symptoms occurs, sometimes as early as three weeks.
2. Reintroduction Phase
Once a measurable improvement in symptoms and overall well-being occurs, the reintroduction phase can begin. During this phase, the avoided foods are gradually reintroduced into the diet, one at a time, based on individual tolerance. The goal is to identify which foods contribute to a person’s symptoms and reintroduce all foods that don’t cause any symptoms while continuing to avoid those that do, allowing for the widest dietary variety a person can tolerate.
Foods should be reintroduced one at a time, allowing for a period of 5-7 days before reintroducing a different food to allow enough time to notice if any symptoms reappear before continuing the reintroduction process. Foods that are well-tolerated can be added back into the diet, while those that trigger symptoms should continue to be avoided. Food tolerance may change over time, so reintroduction tests for foods that initially failed can be repeated periodically.
Step-by-step Reintroduction Protocol:
- Choose one food to reintroduce and plan to consume it a few times per day on the testing day, then avoid it completely for 5-6 days.
- Eat a small amount, such as 1 teaspoon of the food, and wait 15 minutes to see if any reaction occurs.
- If any symptoms are experienced, end the test and avoid this food. If no symptoms occur, eat a slightly larger portion, such as 1 1/2 tablespoons, of the same food and monitor how you feel for 2-3 hours.
- If any symptoms are experienced over this period, end the test and avoid this food. If no symptoms occur, eat a normal portion of the same food and avoid it for 5-6 days without reintroducing any other foods.
- If no symptoms are experienced for 5-6 days, the tested food can be reincorporated into your diet, and repeat this 5-step reintroduction process with a new food.
It’s best to avoid reintroducing foods under circumstances that tend to increase inflammation and make it difficult to interpret results, such as during an infection, following a poor night’s sleep, when feeling unusually stressed, or following a strenuous workout. It is also recommended to reintroduce dairy products with the lowest lactose concentration first, such as ghee or fermented dairy products.
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3. Maintenance Phase
The last AIP phase involves maintaining the protocol and has no specific duration. It aims to provide a healthy diet and lifestyle that will reduce autoimmune responses. In this manner, each patient adopts a dietary pattern associated with a lack of intolerances, considering the reintroduction phase responses.
Foods to Eat and Avoid on the AIP Diet
The AIP diet has strict recommendations regarding which foods to eat or avoid during its elimination phase.
Foods to Avoid
- Grains: rice, wheat, oats, barley, rye, etc., as well as foods derived from them, such as pasta, bread, and breakfast cereals
- Legumes: lentils, beans, peas, peanuts, etc., as well as foods derived from them, such as tofu, tempeh, mock meats, or peanut butter
- Nightshade vegetables: eggplants, peppers, potatoes, tomatoes, tomatillos, etc., as well as spices derived from nightshade vegetables, such as paprika
- Eggs: whole eggs, egg whites, or foods containing these ingredients
- Dairy: cow’s, goat’s, or sheep’s milk, as well as foods derived from these milks, such as cream, cheese, butter, or ghee; dairy-based protein powders or other supplements should also be avoided
- Nuts and seeds: all nuts and seeds and foods derived from them, such as flours, butter, or oils; also includes cocoa and seed-based spices, such as coriander, cumin, anise, fennel, fenugreek, mustard, and nutmeg
- Certain beverages: alcohol and coffee
- Processed vegetable oils: canola, rapeseed, corn, cottonseed, palm kernel, safflower, soybean, or sunflower oils
- Refined or processed sugars: cane or beet sugar, corn syrup, brown rice syrup, and barley malt syrup; also includes sweets, soda, candy, frozen desserts, and chocolate, which may contain these ingredients
- Food additives and artificial sweeteners: trans fats, food colorings, emulsifiers, and thickeners, as well as artificial sweeteners, such as stevia, mannitol, and xylitol
Some AIP protocols further recommend avoiding all fruit - both fresh or dried - during the elimination phase, while others allow the inclusion of 10-40 grams of fructose per day, which amounts to around 1-2 portions of fruit per day. Some also suggest avoiding algae, such as spirulina or chlorella, during the elimination phase, as this type of sea vegetable may also stimulate an immune response.
Foods to Eat
- Vegetables: a variety of vegetables except for nightshade vegetables and algae, which should be avoided
- Fresh fruit: a variety of fresh fruit, in moderation
- Tubers: sweet potatoes, taro, yams, as well as Jerusalem or Chinese artichokes
- Minimally processed meat: wild game, fish, seafood, organ meat, and poultry; meats should be wild, grass-fed or pasture-raised, whenever possible
- Fermented, probiotic-rich foods: nondairy-based fermented food, such as kombucha, sauerkraut, pickles, and coconut kefir; probiotic supplements may also be consumed
- Minimally processed vegetable oils: olive oil, avocado oil, or coconut oil
- Herbs and spices: as long as they’re not derived from a seed or a chilli pepper
- Vinegars: balsamic, apple cider, and red wine vinegar, as long as they’re free of added sugars
- Natural sweeteners: maple syrup and honey, in moderation
- Certain teas: green and black tea at average intakes of up to 3-4 cups per day
- Bone broth
Despite being allowed, some protocols further recommend moderating intake of salt, saturated and omega-6 fats, natural sugars (such as honey or maple syrup), as well as coconut-based foods. Small amounts of fruit may also be allowed, usually amounting to a maximum intake of 10-40 grams of fructose per day, or the equivalent of about 1-2 portions of fresh fruit. Moderating intake of high glycemic fruits and vegetables, including dried fruit, sweet potatoes, and plantain, may also be suggested.
Potential Benefits of the AIP Diet
Research on the AIP diet is limited, but some evidence suggests that it may reduce inflammation and symptoms of certain autoimmune diseases.
Read also: Weight Loss with Low-FODMAP
May Help Heal a Leaky Gut
People with autoimmune diseases often have a leaky gut, and experts believe there may be a link between the inflammation they experience and the permeability of their gut. A healthy gut typically has a low permeability, acting as a good barrier and preventing food and waste remains from leaking into the bloodstream. A highly permeable or leaky gut allows foreign particles to crossover into the bloodstream, possibly causing inflammation.
Foods can influence gut immunity and function, and in some cases, even reduce the degree of inflammation experienced. By helping heal leaky gut, the AIP diet may help reduce the degree of inflammation a person experiences.
May Reduce Inflammation and Symptoms of Some Autoimmune Disorders
To date, the AIP diet has been tested in a small group of people and yielded seemingly positive results.
In an 11-week study in 15 people with IBD on an AIP diet, participants reported experiencing significantly fewer IBD-related symptoms by the end of the study. However, no significant changes in markers of inflammation were observed. Similarly, a small study had people with IBD follow the AIP diet for 11 weeks. Participants reported significant improvements in bowel frequency, stress, and the ability to perform leisure or sport activities as early as 3 weeks into the study.
In another study, 16 women with Hashimoto’s thyroiditis followed the AIP diet for 10 weeks. By the end of the study, inflammation and disease-related symptoms decreased by 29% and 68%, respectively. Participants also reported significant improvements in their quality of life, despite there being no significant differences in their measures of thyroid function.
Although promising, studies remain small and few. Also, to date, they have only been performed on a small subset of people with autoimmune disorders. Therefore, more research is needed before strong conclusions can be made.
Risks and Considerations
The AIP diet is considered an elimination diet, which makes it very restrictive and potentially hard to follow for some, especially in its elimination phase.
- The elimination phase of this diet can also make it difficult for people to eat in social situations, such as at a restaurant or friend’s house, increasing the risk of social isolation.
- There’s no guarantee that this diet will reduce inflammation or disease-related symptoms in all people with autoimmune disorders.
- Remaining in the elimination phase for too long can make it difficult to meet daily nutrient requirements, increasing the risk of developing nutrient deficiencies, as well as poor health over time. The reintroduction phase is crucial and should not be skipped.
- The restrictive nature of the diet may lead to feelings of frustration or anxiety, or may even trigger disordered eating, particularly in individuals with a personal history of it.
It is essential to consult with a healthcare provider or a registered dietitian before starting the AIP diet to ensure it is appropriate and safe for individual needs.
Comparison with Other Diets
AIP Diet vs. Paleo Diet
The AIP diet resembles the paleo diet, both in the types of foods allowed and avoided, as well as in the phases that comprise it. Due to their similarities, many consider the AIP diet an extension of the paleo diet - though AIP may be seen as a stricter version of it.
The Paleo diet originated in the Paleolithic age, at the time of the primitive Homo sapiens, who relied mainly on hunting for food. Thus, the Paleo diet was based on grass-fed, pasture-raised and game meat, small fish, eggs, fruit, leafy vegetables, nuts, and seeds, according to the geographic region. It consists of a whole-food diet, with nutritionally dense foods of high quality.
Several foods are eliminated during its implementation, including processed foods, added sugars (except for honey), artificial sweeteners, grains, dairy, and legumes. Thus, the Paleo diet consists of a specific, horizontal dietary pattern, similar for each patient. On the contrary, the AIP is personalized, with different foods allowed or eliminated, depending on individual tolerance.
Both diet patterns include an elimination phase, but the AIP goes a step beyond the Paleo diet, aiming to minimize the existence of any possible antigen that might trigger an autoimmune response. Individuals who follow the AIP will develop a personalized dietary pattern based on their food tolerances. Accurately implementation of the AIP requires guidance and support, as it is crucial to correctly follow the phases to address individual food sensitivities and health concerns, while the Paleo diet does not require this level of expert guidance and assistance. The AIP elimination phase is stricter, with more foods being excluded than the Paleo diet, including eggs, nuts and seeds, nightshades, food additives, refined oils, coffee, and alcohol.
AIP Diet vs. Other Elimination Diets
The basis for elimination diets dates back to the Paleolithic era due to the need to search for food and the limited options available at different times. The subsequent reference to food elimination was made by Hippocrates in 400 BC, referring to lactose intolerance, suggesting eliminating dairy products to relieve discomfort. The term “elimination diets” was first reported in 1926 by Dr. Rowe in 1944. During the same period, the elimination of gluten among patients with celiac disease was reported. In the early 2000s, the fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAP) diet emerged as another iteration of elimination diets recommended for alleviating symptoms of irritable bowel syndrome. Over the past decade, specific forms of elimination diets, including the AIP and the Wahls protocol, appeared and were recommended for autoimmune diseases and multiple sclerosis, respectively.
Clinical Evidence and Research
Elimination diets have long been used to manage diseases, including celiac disease, allergies, and inflammatory bowel disease (IBD). Regarding autoimmune diseases, the AIP diet has been implemented in organ-specific and systemic autoimmune diseases such as Hashimoto thyroiditis (HT), IBD and rheumatoid arthritis (RA), improving QoL and disease-related symptoms.
Studies on Hashimoto's Thyroiditis (HT)
Two uncontrolled clinical trials concluded that patients undergoing the AIP improved and showed that the physical and emotional statuses had less malaise and enhanced general health subscales. One study reported improvement in physical and emotional well-being, while the other reported decreased thyroid gland volume and lower free tri-iodothyronine (fT3) and free thyroxine (fT4) concentrations. At the same time, anti-thyroid autoantibodies (anti-TPO) increased, and thyroid stimulating hormone (TSH) concentrations decreased. Since fT3 and fT4 concentrations were reduced, while TSH and anti-TPO concentrations remained unchanged, adherence to the AIP may worsen thyroid function. Inflammatory markers improved significantly post-intervention. Regarding the anthropometric indices, one study reported a decrease in body mass index (BMI), body fat (as a % of body weight) and muscle mass, indicating a calorie deficit, while the other recorded a decrease in body weight and BMI.
Studies on Inflammatory Bowel Disease (IBD)
One uncontrolled trial implemented the AIP in patients with active disease for 11 weeks. Clinical remission and endoscopic improvement were documented in most patients as opposed to inflammatory markers (C-reactive protein, fecal calprotectin), which remained unaltered. Based on further analysis, treatment with biological therapy did not affect outcomes.
Studies on Rheumatoid Arthritis (RA)
In systemic autoimmune diseases, a non-randomized, crossover trial was conducted in patients with RA, comparing QoL measures following the AIP against the usual diet.
Adverse Events
The HT studies had no moderate-to-severe adverse events, although some participants had mental challenges during the elimination phase.
Practical Considerations
- Consultation with Healthcare Professionals: Before starting the AIP diet, it’s crucial to consult with a healthcare provider or a qualified health coach to ensure nutrient needs are met.
- Comprehensive Approach: Managing autoimmunity requires a comprehensive and holistic approach that extends beyond dietary changes, including regular exercise, good sleep, and stress management.
- Personalization: The goal of the AIP diet isn’t to follow it indefinitely, but to identify and remove trigger foods, heal the gut, and then gradually reintroduce foods back into the diet.