What Is the Autoimmune Protocol (AIP) Diet?

Last updated: May 2022

Rheumatoid arthritis (RA) occurs when your immune system attacks joints, cartilage, and other body parts. Experts do not know what causes this autoimmune reaction. One theory is that certain genetic factors make people with RA more vulnerable to environmental factors, such as infections.

Gut health and the gut microbiome

Many environmental factors affect your gut microbiome (the bacteria in your intestine). These bacteria help maintain the gut lining, which prevents bacteria and toxins from triggering immune reactions outside the gut. People with autoimmune conditions like RA often have a weaker gut lining.

The gut microbiome is sensitive to the foods we eat. Certain food ingredients may strengthen the gut lining, while others may cause inflammation. Experts have developed diets, such as the autoimmune protocol (AIP) diet, based on this idea. It will not cure RA, but it may reduce symptoms such as inflammation.

How is diet linked to rheumatoid arthritis?

There is no evidence that any specific diet relieves symptoms of RA. However, there is a growing theory that certain foods can improve your gut health and reduce inflammation. The goal is to eliminate foods that may cause inflammation and reintroduce them slowly to see how each food affects you.

What is a leaky gut?

Many diets designed to reduce inflammation are based on the idea that people with autoimmune conditions have a “leaky gut.” The gut lining (also called the intestinal barrier) contains the pro-inflammatory bacteria and toxins within the intestine. When this barrier is permeable or “leaky,” food toxins can enter the bloodstream and trigger inflammatory reactions.1,2

The bacteria in your intestine (your gut microbiome) help maintain the gut lining. Nutrients and food ingredients can affect how well the microbiome maintains the gut lining. For example, vitamin D and fiber help maintain the gut lining. Stressors like alcohol weaken the gut lining. This is why many experts think dietary changes can reverse gut leakiness and reduce symptoms of RA.1,3

What is the autoimmune protocol diet?

The AIP diet includes foods with nutrients that heal the gut lining. It tries to avoid foods that may cause inflammation. The goals of the AIP diet are to:4

  • Avoid irritating the gut with food
  • Heal holes in the gut lining
  • Reduce inflammation and immune reactions

The AIP diet usually removes the same foods as the Paleo diet, as well as nuts, seeds, and artificial sweeteners. In general, it allows you to eat:4

  • Meat and fish
  • Most vegetables
  • Fruit
  • Sweet potatoes
  • Coconut milk
  • Fresh, non-seed herbs
  • Green tea
  • Vinegar
  • Dairy-free fermented foods (like kombucha)
  • Avocado, olive, and coconut oil

The AIP diet does not allow you to eat:4

  • Grains (oats, wheat, and rice)
  • Dairy
  • Eggs
  • Nuts, seeds, legumes, and beans
  • Tomatoes, potatoes, eggplants, peppers
  • Sugars (including sweeteners)
  • Butter
  • Oils
  • Herbs from seeds
  • Processed foods
  • Chocolate
  • Alcohol

This diet is very restrictive and is not meant to be used long-term. Over time, it can result in nutrition deficiencies and complications. The AIP diet is instead meant to identify foods that trigger symptoms by slowly reintroducing them after you eliminate them.

Can the AIP diet help people with RA?

There is not much research done on the AIP diet for people with RA. Two small studies have shown that the AIP diet can help people with inflammatory bowel disease (IBD) and Hashimoto’s thyroiditis (HT). Many people with RA develop these conditions.5

One study enrolled 15 people with IBD (Crohn’s disease or ulcerative colitis). They phased out the foods not allowed in the AIP diet over 6 weeks before maintaining the diet for 5 weeks. Eleven of the 15 participants showed complete remission by week 6.6

Another study enrolled 17 women with Hashimoto’s thyroiditis, which is an autoimmune condition affecting the thyroid gland. They carried out the AIP diet over 10 weeks. The AIP diet reduced symptom burden and indicators of inflammation.7

However, these studies are very small and are not proper clinical trials. We still need more research to understand exactly how the AIP diet should be used by people with RA and other autoimmune conditions.

Other diets for people with RA try

One diet that may reduce symptoms for people with RA is a lectin-free diet. Lectins are proteins that may damage the gut lining. This diet excludes beans, lentils, grains, and most dairy products.4

Another diet that helps some people with RA is a low FODMAP diet. FODMAPs are sugars that are not easily digested. For people with RA who experience bloating, gas, or diarrhea, a low FODMAP diet may help by reducing inflammation. This diet excludes wheat and certain fruits, vegetables, and dairy products.4

If you are considering the AIP or any other diet, talk to your doctor. They can help you develop a plan to ensure you still get enough nutrients. They may encourage you to eliminate certain foods before slowly reintroducing them back into your diet.

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