What is GAPS Diet? Does It Work?

Are you determining whether or not GAPS diet is a good fit for you or your family? You may have heard amazing healing journeys from some friends, and not-so-positive ones from others. Mixed experiences like this can be very confusing for people, especially parents who want to heal their children. I see both of these categories in my functional medicine clinic in Singapore, often when GAPS fails. I will explain, to the best of my ability, why GAPS may sometimes fail.

What is the GAPS Diet?

GAPS diet first originated from the Specific Carbohydrate Diet, popularized by Elaine Gottschall in her book, Breaking the Vicious Cycle. This was slightly modified by Dr. Campbell-McBride, further restricting certain foods and focusing on healing nutrients. The aim of the GAPS diet is to reduce intestinal dysbiosis, limit carbohydrates or starches that feed gut dysbiosis, and simultaneously provide gut-healing nutrients.

Her experience has been that healing the gut provides beneficial effects in the nervous system, which reduces symptoms of autism, ADHD, depression and schizophrenia. I second that experience, as I have personally helped patients improve psychological symptoms by healing the intestines. This is a core tenet of gastrointestinal medicine at my practice.

Has the GAPS Diet Been Proven To Work?

The GAPS diet has never been scientifically validated for “curing” schizophrenics, autistic children, depressed patients, or those with ADHD. There are many doctors concerned about the GAPS diet, saying it lacks certain essential nutrients, and that it is not a long-term healthy diet. I agree with this sentiment.

I have recommended GAPS to some families, but more often than not, I recommend the specific carbohydrate diet mentioned above. Now, why would I recommend it if it’s not scientifically validated, per se?

Because I do believe it can benefit some patients. Remember, the goal of a naturopathic physician like me is to uncover the underlying cause of why someone is ill. For many children with ADHD, autism, depression, etc, the underlying cause is malabsorption, gut dysbiosis, leaky gut syndrome, or intestinal inflammation. This may be the underlying cause for many children, but not for all!

The purpose of the GAPS diet is not to replace a normal diet. The GAPS diet, I believe, should be used for a short to moderate amount of time, usually 2- 6 months but sometimes longer, to eliminate gut dysbiosis and inflammation and stimulate healing of enterocytes (the intestinal cells). The goal is to completely heal the gut, discover which food allergens/sensitivities are a problem, and then progress to a long-term well-rounded diet. I highly recommend the anti-inflammatory diet as a long-term dietary strategy. A lot of research has supported long-term anti-inflammatory diets like the Mediterranean diet for disease prevention and health promotion.

Why Would The GAPS Diet Fail?

There are three primary reasons why a patient’s experiment with GAPS may be viewed as a failure:

1) The gastrointestinal system was not the main underlying cause, although it can play a role
2) The GAPS diet failed to address the gastrointestinal problem
3) Other fundamental issues which potentially brought more obvious issues to the surface

If the GAPS diet fails because of #1, parents and physicians need to spend quite a bit of time investigating other options. I highly recommend seeing a competent physician who can order basic blood tests, including a whole-blood lead test (every child should be screened at least once in their lifetime), complete blood count (to screen for anemia), ferritin to check for low iron, thyroid, and vitamin D.

If the GAPS diet fails because of #2: We need to talk.
There are a lot of things I really love about the Gut and Psychology Syndrome book. Dr. Campbell-McBride does a great job of explaining basic anatomy and physiology of the gastrointestinal system. She explains how enzymes work to digest our food, insulin and blood sugar, the role of the immune system in the gut, and the role of beneficial bacteria in the intestines.

There are a few things, though, that I don’t care for, and I will explain them here:

First and foremost, the method claims to be a cure-all for children with autism and other neurological disorders. Not only does this sometimes lead to false hopes, but it also perpetuates Mom Guilt if the diet does fail. The GAPS diet CAN work – but as I mentioned earlier, it does not work for all kids. When trying the GAPS diet I tell parents that they should think of it as a therapeutic trial – if leaky gut and malabsorption is the cause of their child’s condition, then the GAPS diet will improve their symptoms. If their symptoms do not improve then we need to look elsewhere. Autism, ADHD, depression, schizophrenia, anxiety – all of these are multifactorial diseases and disorders – it is unrealistic to expect that all people will be cured with the GAPS diet.

Secondly, there are a few things that I don’t agree with in the book. One is the idea that putting a small amount of food on the skin (she recommends the wrist) is an accurate test for food sensitivities. There is no research to support this. If a patient does have a skin reaction it is quite likely they will have an intestinal reaction (almost undoubtedly). But the opposite is not true at all: the absence of a skin reaction does not mean there is no food allergy. There are several other small points in the book that I disagree with too (using aspirin for fevers, length of the diet, etc., etc), but I won’t get nit-picky here, I just want to remind readers that one book is not the be-all-end-all for health.

Thirdly, the book fails to identify common insensitivities and allergies. Many of my patients (if not most) do not tolerate dairy in any form, whether fermented or not. Similarly, many patients have coconut, egg, tomato, potato or tree nut sensitivities. When these patients start adding these foods on the GAPS diet they sometimes forget to go slow and add foods one at a time. If the symptoms do not resolve in the elimination phase (bone broth only), then something is wrong.

I also think it is unreasonable that the GAPS diet includes fermented foods, considering the target audience. I would say about 50% of my patients cannot tolerate any amount of fermented products, even homemade. Obviously they are incredibly beneficial. But, in few people, it can excacerbate dysbiosis especially yeast and can definitely screw up thyroid issues especially in people dealing with hashimotos. I use a FOS-free probiotic for my patients (my favorite is, Klaire Labs SCD compliant probiotic and sometimes I do use the 5 strain Bifido powder custom probiotics, no affiliation).

Additionally, coffee, wine, and vinegar are present in the diet. Most of my patients do not tolerate these beverages as they seem to irritate the gut lining. Vinegar is often better tolerated, but for some sensitive patients they just cannot handle it, at least initially.

Lastly, the GAPS diet contains too many animal fats. This is by far the biggest limitation of the GAPS diet for long-term health. Animal fats are helpful in that they contain vitamin K2 and provide a much-needed source of calories on this diet. However, animal fats tend to be inflammatory. The Weston A. Price folks would disagree with me on this one, but so far all the research still suggests that animal fats are pro-inflammatory. Granted, grass-fed and free-range beef are significantly less inflammatory (perhaps even bordering on anti-inflammatory?) than their grain-fed counterparts.

I hesitate to recommend a long-term GAPS diet because of the high amount of animal fats. All of the best researched and referenced diets in scientific literature are low in animal proteins and incredibly high in colorful fruits and vegetables. The Mediterranean diet, which I consider to be the best-referenced, best-researched all-purpose diet, is low in animal meats but high in vegetables and fatty fish.

For patients who do not respond to the traditional meat stock introduction, OR have documented oxidative stress (tested through something like (DNA oxidative stress test, I use DUTCH labs) OR have inflammatory conditions like Crohn’s, Colitis, hypertension, atherosclerosis, asthma, thyroiditis, any other autoimmune condition (like rheumatoid arthritis, lupus, etc.) I recommend a modified GAPS introduction using vegetable juices in lieu of the bone broth. Organic, fresh-pressed juices using copious green leafy vegetables, cabbage and only a small amount of sweetener (like a 1/2 apple, one carrot, or some beets) are suggested. Foods can be added back in according to the GAPS introduction diet, though of course there will not exactly be a “soup” to add them to.

The GAPS diet is also very low-starch. Although the whole principle is to starve the bacteria by eliminating sugars and starches. Low carb diets may be too limiting and not work for some people. Adding safe starches may be essential in these cases.

Genetics also comes into play. If we look through this lens, high protein diets are high in methionine. Methionine loading can increase homocysteine, hydrogen sulfide, taurine and ammonia. Irrespective of the person having a CBS mutation or not, this pathway is upregulated trying to eliminate the methionine excess.

Furthermore, the GAPS diet does not take blood types into account. Some blood types do well on high protein and others on high carb diets. Eg: blood Type O’s might do great on GAPS. They have plenty of stomach acid to digest meat efficiently and can do poorly on grain. Blood Type A’s have a weak digestive system and often lack stomach acid but can do well on grains, fruits, veggies (see Peter Adamo’s book on Blood type diets).

Another issue: insufficient fiber in the GAPS diet. Insufficient fiber intake for a long term can alter gut microbial flora and can cause further dysbiosis leading to new food intolerances in a few. So, I again emphasize short term for restricted diets.

Finally for now, the GAPS diet does not push the addition of anti-microbials. I believe this is the number one cause for GAPS-diet failure. When I have a patient who has been on the GAPS diet and either improved only slightly or improved and then regressed, I always look for gut dysbiosis. Yeast overgrowth, overgrowth of pathogenic bacteria, or Small Intestinal Bacterial Overgrowth (SIBO) are incredibly common conditions in our era of frequent antibiotic-use and stress.

The GAPS diet is definitely designed to eliminate gut dysbiosis by “starving” bad bacteria and providing good bacteria from fermented foods. But for people with incredibly high bacterial/yeast loads the GAPS diet simply isn’t going to be enough. Remember, even if a patient is completely fasting there will still be some food supply for the microorganisms just from the sloughing off of dead intestinal cells. In other words, starving out bacteria usually isn’t good enough. (Unless you do actually starve, and I don’t recommend that!) Even bone broth, though it is low in fermentable sugars, does contain a very small amount of food which can be just enough for dysbiotic flora to live in.

If you have improved on the GAPS diet in the past but then gotten worse as you introduced new foods or returned to a semi-normal diet I highly recommend checking for gut dysbiosis. Naturopathic doctors often have stool culture kits in their office to check for a variety of organisms. Bacteria, yeast and parasites may all be present, and it is usually necessary to do more than 1 stool sample (an O&Px3 is standard for parasites, for example – meaning it checks for ova & parasites three times).

If that ends up negative and you still have gastrointestinal symptoms, especially symptoms of pain shortly after eating or significant gas and bloating with a distended abdomen, then I recommend doing a test for Small Intestinal Bacterial Overgrowth (or “SIBO”).

Whether SIBO or another type of gut dysbiosis is detected there are several different antimicrobials that can be added to the GAPS regimen to help speed up the elimination of the organisms. Though I usually use herbal antimicrobials, sometimes it may even be necessary to add in prescription antibiotics, anti-fungals or anti-parasitics if there is a very high microbial load. This should be done carefully, obviously, so as to not cause more dysbiosis. Once the pathogens have been eliminated most patients will fully recover, and the GAPS diet could be resumed (if paused during treatment) to fully restore proper gut health.

In the last few years, I have noticed a trend in parents trying the GAPS on their own, either after reading a book or getting advice from other mom bloggers and friends. If you decide to go on GAPS, discuss with your naturopathic physician in Singapore if it may be a good fit and to consider modifications for each individual types as needed. A GAPS nutritionist can then help provide support to navigate through the whole complex process.

(This post turned out way too long than I would have imagined !)