The term “GAPS” stands for “gut and psychology syndrome.” The GAPS diet follows the notion that gut health is linked with overall physical and mental health.
In this theory, improving gut health can improve other health conditions.
Researchers have not yet fully explored this diet. There is currently limited evidence to suggest that the diet can treat the health conditions it claims to, and there are several controversies around the premise of this diet.
In this article, we look at the evidence for the GAPS diet’s claims, how to follow it, and its possible benefits. We also provide example food lists and meal plans.
What is the GAPS diet?
The GAPS diet involves replacing foods that are difficult to digest with nutrient-rich food.
Dr. Natasha Campbell-McBride, who invented the GAPS diet, believes that poor nutrition and a leaky gut, or increased intestinal permeability, are responsible for many psychological, neurological, and behavioral issues.
At the core of the GAPS diet, people avoid foods that are difficult to digest and might damage the gut flora or gut lining. They replace them with nutrient-rich foods that help the gut heal.
According to the GAPS theory, a leaky gut releases harmful bacteria and toxins into the bloodstream, which then travel to the brain and interfere with the brain functioning. The theory says that eliminating foods that damage the gut could help treat conditions such as autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD), and dyslexia.
Although current research suggests that there is a connection between the brain and the gut, particularly for conditions such as anxiety and depression, there is no strong evidence to suggest that following the GAPS diet will improve psychological or behavioral conditions.
Which conditions does the GAPS diet target?
Dr. Campbell-McBride originally designed the GAPS diet with the aim of treating her son’s autism. Some people also use the GAPS diet as an alternative therapy for a range of psychological and behavioral conditions, including:
Dr. Campbell-McBride’s initial aim with the GAPS diet was to help children with behavioral and mood disorders. However, some adults now use it to improve digestive problems.
The GAPS diet and autism
Dr. Campbell-McBride believes that children develop autism due to poor nutrition and leaky gut syndrome. She claims that the GAPS diet can “cure” or improve symptoms of autism.
ASD causes a range of symptoms that affect how a person experiences the world and interacts in social settings. Scientists believe that a combination of genetic and environmental factors contribute to the development of ASD.
Most experts agree that there is no cure for ASD. Many people with ASD do not see autism as something that they need to cure or treat. It is possible, however, to improve health conditions associated with ASD, such as gastrointestinal (GI) problems.
One 2014 systematic review found that children with ASD had significantly higher rates of GI symptoms than those without. The authors say that children with ASD were more prone to abdominal pain, constipation, and diarrhea. It is not yet clear why this is the case.
One case study reported that a 12-year-old boy showed significant reductions in GI symptoms and core autism symptoms after 4 weeks of probiotic treatment.
However, findings from a 2014 study that tested 133 children found no association between intestinal permeability and the presence of ASD symptoms.
To date, there is no solid evidence to suggest that dietary changes can substantially affect ASD.
Are there benefits to the GAPS diet?
There is no strong evidence to suggest that the GAPS diet can help treat the conditions it claims to.
Following this diet could, however, improve a person’s gut health. It encourages people to eat fewer processed foods and more fruits, vegetables, and natural fats. These simple dietary changes could improve gut health and overall health.
However, GAPS diet guidelines do not explicitly account for all nutritional needs. When following this diet, people should make sure that they are getting enough vitamins and minerals to avoid developing nutritional deficiencies.
The following sections discuss the evidence for possible benefits of the GAPS diet.
Improving gut health
The GAPS diet could improve gut health in three main ways:
- Eliminating artificial sweeteners: According to some animal studies, artificial sweeteners can create imbalances in gut bacteria and increase the risk of metabolic problems.
- Focusing on fruits and vegetables: A 2016 study involving 122 people showed that eating fruits and vegetables can prevent a potentially harmful strain of bacteria from growing in the gut.
- Including probiotics: Probiotics contain many beneficial bacteria. One study suggests that eating probiotic yogurt may help lower blood sugar levels among people with metabolic syndrome.
Possibly managing some psychological and behavioral conditions
According to a review study, recent clinical studies have suggested that microbes in the gut can significantly affect brain function.
The researchers suggest that gut imbalances could contribute to schizophrenia and other complex behavioral conditions.
Findings from a 2019 systematic review suggest that probiotics have strong therapeutic potential for treating depressive symptoms.
However, there is currently no solid research to suggest that changing the diet can effectively treat these conditions.
How do you follow the GAPS diet?
To follow the GAPS diet, eliminate grains, sugar, soy, pasteurized dairy, starchy vegetables, and processed foods from the diet.
The diet is very restrictive and may take up to 2 years to complete.
There are three stages to the GAPS diet:
1. The introduction diet
A person can add avocado at stage 3 of the introduction diet.
Dr. Campbell-McBride recommends that people follow the introduction diet before starting the full GAPS diet.
While highly restrictive, this phase aims to heal the gut and reduce digestive symptoms quickly. It can last anywhere from a few weeks to 1 year.
The introduction diet has six progressive stages. Each stage introduces new foods. People should not progress to the next stage if they experience digestive symptoms, which may include:
- abdominal pain
In stage 1, the diet consists of:
- homemade bone broth
- boiled meat or fish
- well-cooked vegetables
- probiotics, such as fermented vegetable juices, yogurt or kefir, and homemade fermented whey
- ginger or chamomile tea with raw honey
- purified water
In stage 2, add the following foods:
- raw, organic egg yolks
- casseroles made with meats and vegetables
- fermented fish
- homemade ghee
In stage 3, add the following foods:
- sauerkraut and fermented vegetables
- GAPS pancakes
- scrambled eggs made with ghee, goose fat, or duck fat
- probiotic supplements
In stage 4, add the following foods:
- roasted or grilled meats
- cold-pressed olive oil
- freshly pressed carrot juice
- GAPS milkshake
- GAPS bread
In stage 5, add the following foods:
- cooked apple purée
- raw vegetables, such as lettuce and peeled cucumber
- pressed fruit juice
In stage 6, add the following foods:
- raw, peeled apple
- raw fruit
- increase honey
- baked goods sweetened with dried fruit
After completing the introduction diet, many people move onto the full GAPS diet.
2. The full GAPS diet
During the GAPS diet, avoid all grains, sugars, starchy vegetables, refined carbohydrates, and processed foods. This stage lasts 1.5–2 years.
Acceptable GAPS foods include:
- meat, fish, and shellfish (fresh or frozen only)
- fresh vegetables and fruit
- natural fats, such as olive oil, coconut oil, and ghee
- a moderate amount of nuts
- GAPS baked goods made using nut flour
The GAPS diet also recommends that people:
- use organic food as often as possible
- avoid all processed and packaged foods
- eat fermented food with every meal
- drink bone broth with every meal
- avoid eating fruit with meals
- combine all protein food with vegetables, which the theory says will keep body acidity levels normal
3. The reintroduction phase
After at least 6 months of normal digestion, people can choose to move on to the reintroduction phase.
The final stage of the GAPS diet involves gradually reintroducing food items over the course of several months.
The diet recommends starting with potatoes and fermented grains. Start with small portions and gradually increase the amount of food, as long as no digestive issues arise. Continue this process with starchy vegetables, grains, and beans.
After completing the GAPS diet, many people continue to avoid refined, highly processed foods.
The GAPS diet food list
People can eat eggs on the GAPS diet.
People can eat the following foods on the GAPS diet:
- bone broth
- meats, preferably hormone-free or grass-fed
- animal fats
- fresh fruits and non-starchy vegetables
- fermented foods and beverages
- hard, natural cheeses
- coconuts, coconut milk, and coconut oil
- dry wine
- white navy beans
Foods to avoid on the GAPS diet include:
- sugar and artificial sweeteners
- alcohol, but adults can have a glass of dry wine occasionally
- processed and packaged foods
- grains such as rice, corn, wheat, and oats
- starchy vegetables, such as potatoes and yams
- beans, except white and greens beans
- strong tea
Sample GAPS diet meal plan
Start the day with one of the following:
- a glass of filtered lemon water and kefir
- a glass of freshly pressed fruit and vegetable juice
- GAPS pancakes topped with butter or honey
- one cup of lemon and ginger tea
- meat or fish with vegetables
- one cup of homemade bone broth
- one serving of probiotics, such as kimchi, sauerkraut, yogurt, or kefir
- homemade vegetable soup made with bone broth
- one serving of probiotics, such as kimchi, sauerkraut, yogurt, or kefir
The GAPS diet claims to help treat autism and other behavioral and psychological conditions. However, no credible research findings support these claims.
As is common in the diet industry, the GAPS diet appears to be part of a larger marketing scheme. Alongside offering dietary advice, the official website sells books, supplements, DVDs, essential oils, organic bitters, and more.
People should therefore proceed with caution.
Those interested in trying the GAPS diet can consult a licensed GAPS practitioner to learn more. However, people should first consider consulting a registered dietitian or other healthcare provider.