The GAPS diet is a type of elimination diet aimed at healing the gut and promoting overall gut health. The premise behind the diet is that a number of health conditions, specifically digestive disorders and neurodivergent conditions—like autism and attention deficit hyperactivity disorder (ADHD)—might be caused by what is scientifically known as intestinal hyperpermeability, commonly called leaky gut. The GAPS diet claims that healing a leaky gut might improve or cure these conditions.
However, research and scientific evidence is lacking to back up the GAPS diet. Let's take a deep dive into what the GAPS diet claims to treat, how to follow it, what you can and cannot eat, and the benefits and risks of the GAPS diet guidelines.
Best Foods to Eat for Gut Health
What Is the GAPS Diet?
GAPS stands for Gut and Psychology Syndrome, a term developed by Natasha Campbell-McBride, who holds degrees in medicine, neurology and nutrition, to describe connections between the digestive system and the brain. Campbell-McBride created the GAPS diet in 2004 after researching the relationship between food, nutrition, gut and brain health while seeking answers for her own child who was diagnosed with learning disabilities. She has since also added Gut and Physiology Syndrome (still GAPS) to Gut and Psychology Syndrome, which is concerned with the gut's potential role in some chronic physical conditions.
According to the GAPS diet website, GAPS theorizes that many health conditions are rooted in an unhealthy gut, and if one's gut is healed, then various digestive, neurological and autoimmune conditions might also be resolved. These claims are made related to conditions including autoimmune diseases, like celiac disease, Crohn's disease and rheumatoid arthritis; food allergies and intolerances; thyroid disorders; and other digestive disorders like irritable bowel syndrome (IBS). Neurological and psychiatric conditions like autism, ADHD, schizophrenia and bipolar disorder are also included in GAPS diet claims.
It is important to note that there are no peer-reviewed scientific studies examining the efficacy of the GAPS diet. Most success stories are anecdotal and come from Campbell-McBride's books and from her clinic based in the United Kingdom.
What Can You Eat on the GAPS Diet?
Introduction Diet
There are three phases of the GAPS diet: the introduction, the full GAPS diet and the reintroduction. There is also a dairy introduction phase, explained in more detail in the books. For those looking to follow the diet, Campbell-McBride recommends you purchase the books, Gut and Psychology Syndrome and Gut and Physiology Syndrome, so you can follow each stage as recommended.
The Introduction Diet has six stages, with the goal being to heal a leaky gut before moving on to the full GAPS diet. The intestinal lining is made up of cells that are supposed to absorb water and nutrients and get them into the bloodstream. Think of this intestinal lining as a protective barrier. If this barrier gets holes or cracks in it, undigested food and toxic bacteria can seep out into the body, causing inflammation and digestive issues. This is called intestinal hyperpermeability or leaky gut.
The foundational foods in the introduction phase include meat stocks and broths, soups and fermented foods. How long you stay in each stage varies anywhere from three to five days or four to six weeks or more. Once diarrhea or other severe digestive symptoms have resolved, you can move on to the next stage. Campbell-McBride says it's important to introduce small amounts of foods slowly as you move through the stages to see what you can tolerate. The foods allowed in the six stages of the Introduction Diet are as follows:
Stage 1: Homemade meat or fish stock; homemade soups with meat or fish stock; dairy- or vegetable-based probiotic foods; ginger tea.
Stage 2: Continue foods in Stage 1. Add raw organic egg yolks; stews or casseroles made with meats and vegetables; homemade yogurt or kefir; juice from sauerkraut or vegetables; fermented fish; homemade ghee.
Stage 3: Add ripe avocado; GAPS pancakes (recipe in book); eggs scrambled with ghee, goose fat or duck fat; sauerkraut; fermented vegetables.
Stage 4: Gradually add roasted and grilled meats; cold-pressed olive oil; freshly pressed juices; baked bread with ground nuts or seeds.
Stage 5: Add cooked apple puree and raw vegetables, starting with lettuce and peeled cucumber. Avoid citrus.
Stage 6: Add peeled raw apple; add other raw fruit and honey as tolerated.
Full GAPS Diet
The full GAPS diet introduces more foods aimed at healing and restoring the gut, according to Campbell-McBride. She recommends that people follow the full GAPS diet for 18 months to two years. On the diet, about 85% of the foods you consume daily should be from:
- Meat
- Fish
- Broth
- Eggs
- Fermented foods
- Vegetables
Fruit is also OK, along with baked goods made with nut or seed flours. See below for a more extensive list of foods you can and cannot eat.
Reintroduction Phase
After six months of normal digestion and bowel movements, you can start the reintroduction phase. During this time, you can start to add foods back into your diet, slowly and a little at a time, to see how you tolerate them. If you have no symptoms, you can increase portions.
There is no exact order of foods to reintroduce; however, Campbell-McBride recommends starting with potatoes and fermented gluten-free grains. She also recommends that people following the GAPS diet continue avoiding highly processed foods and foods high in added sugar.
GAPS Diet Food List
For an extensive list of foods you can and cannot eat, refer to the GAPS website and books.
Foods You Can Eat on the GAPS Diet
- Eggs
- Meat
- Stock
- Fish
- Shellfish
- Fresh vegetables
- Fruit
- Nuts
- Seeds
- Garlic
- Olive oil
Foods You Cannot Eat on the GAPS Diet
- Grains
- Sugar
- Potatoes
- Parsnips
- Soy
- Commercial yogurt
- Cottage cheese
- Rice
- Oats
- Coffee
- Corn
- Artificial sweeteners
- All processed foods in packages or tins
- Milk from any animal; soymilk, rice milk or canned coconut milk
Other GAPS Diet Recommendations
- Consume fresh and frozen meat from high-quality sources only—no canned, smoked or processed meats
- Consume wild-caught, fresh or frozen fish only
- Consume only cold-pressed, organic, raw plant oils
- Cook only with animal fat, coconut oil or ghee
- Do not microwave food
It is important to reiterate that there is little—if any—scientific support for the restrictiveness and specificity of this diet. Additionally, meats and seafood can come from high-quality sources even if they are canned, though the diet excludes canned foods (confused yet?).
Are There Benefits to the GAPS Diet?
The GAPS diet emphasizes vegetables and fermented foods, both of which have been linked to a healthy gut. Studies, like a 2022 review in Microorganisms, suggest that eating a variety of fruits and vegetables, olive oil and fatty fish can help maintain a healthy balance of bacteria in the gut, whereas a diet high in saturated fat and refined carbohydrates and low in fiber—aka a traditional Western diet—might cause an imbalance of gut bacteria.
A 2022 review in Nutrients suggests that fermented foods like kefir and sauerkraut, along with probiotic-rich foods like yogurt, can help improve the gut microbiota. And limiting highly processed foods with added sugar, refined grains and artificial sweeteners is also beneficial to overall health. Refined carbohydrates and sugar can increase inflammation in the body, and some studies, like a 2021 review in Frontiers in Nutrition, have shown that consumption of artificial sweeteners can alter gut bacteria.
Downsides of the GAPS Diet
There are no peer-reviewed clinical studies assessing the GAPS diet or proving it effective at healing the gut and treating the conditions it claims to cure. In addition, it's unclear if a leaky gut is the result of having a certain condition and not the cause.
While scientists agree that leaky gut can occur, research hasn't shown that improving the intestinal barrier necessarily treats or improves any specific conditions, per a 2019 review published in the journal Gut.
The GAPS diet is extremely restrictive, which has several consequences. For starters, this makes it time-consuming to plan and cook meals. More concerning, however, is that the diet was originally developed to help children suffering from behavioral and digestive issues. Putting children—or adults for that matter—on an extremely restrictive diet can lead to malnutrition and/or disordered eating patterns. Not to mention, highly restrictive plans are not usually enjoyable or sustainable for a long period of time, which negates any results they might promise. In addition, it appears to be gluten-free as it doesn't allow any grains.
It's extremely important to weigh the risks and benefits of the GAPS diet, especially given that there is no substantial evidence that it provides any health benefits and its potential to cause harm.
Sample GAPS Diet Meal Plan
Breakfast
Egg scramble with zucchini, spinach, tomatoes and Gorgonzola cheese
Lunch
Spinach salad with broccoli, carrots, tomatoes, chicken, avocado, walnuts and blue cheese
Homemade dressing with olive oil and apple cider vinegar
Dinner
Lemon-garlic salmon with homemade tzatziki (Greek yogurt, lemon juice, cucumber, dill)
Roasted Brussels sprouts and butternut squash
The Bottom Line
So, should you try the GAPS diet? In my opinion, no. This dietitian does not recommend the GAPS diet, given that there is no research to back its claims or efficacy. In addition, it is extremely restrictive, time-consuming and relatively expensive. There are more effective, science-backed ways to improve digestive and neurological disorders that incorporate small changes that are sustainable. We highly recommend working with a gastroenterologist who can diagnose your condition and a registered dietitian nutritionist (RDN) who specializes in that condition and who can provide specific solutions tailored to your food preferences and lifestyle.
