I have read a lot of claims regarding GAP syndrome and GAPS diet with the most surprising of them being that the proposed diet can even cure disorders such as autism and schizophrenia. For example in this link, Dr Campbell states:

...The toxicity, which is produced by the abnormal microbial mass in these patients, establishes a link between the gut and the brain. That is why I grouped these disorders under one name: the Gut and Psychology Syndrome (GAP Syndrome or GAPS). The GAPS children and adults can present with symptoms of autism, ADHD, ADD, OCD, dyslexia, dyspraxia, schizophrenia, depression, bipolar disorder, sleep disorders, allergies, asthma and eczema in any possible combination. These are the patients who fall in the gap in our medical knowledge. Any child or adult with a learning disability, neurological or psychological problems and allergies should be thoroughly examined for gut dysbiosis. Re-establishing normal gut flora and treating the digestive system of the person has to be the number one treatment for these disorders, before considering any other treatments with drugs or otherwise.

Although these claims seem unrealistic to me, I would like to find solid scientific evidence that refutes them.

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    Wow! A trademarked disease. Don't know why but I smell scam...
    – nico
    Apr 8, 2012 at 18:04
  • Note: even if the claim was true, it would be curing GAPS that was presenting with symptoms like the others. not curing those others themselves. It would be crazy to assume GAPS first even I'd there was any evidence that it existed. Frankly I'm hugely skeptical of this being the case. The danger is that this is treated wrongly as a "new cure" for classic disorders. A schizophrenic dropping their meds for this without consuling a doctor could be very dangerous. Apr 8, 2012 at 18:11
  • reading through that I'm already skeptical by the simple fact that he always mentions the gut instead of small and big intestines. Also how would bacteria get from the "gut" to the breast milk? Apr 9, 2012 at 1:08
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    also the disclaimer in a barely contrasting color "*The statements on this site have not been evaluated by the Food and Drug Administration. Nothing on this site is intended to diagnose, treat, cure, or prevent any disease. " Apr 9, 2012 at 1:09
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    @Anon - "It's common sense that what happens in your body has an effect on your brain..." This is the entire reason why the Scientific method was developed. Common sense is not the truth. It is not evidence. It means nothing until it has been proven or there's a correlation shown. That people are skeptical of claims, many of which are "Common sense", is the entire reason for this website's existence.
    – MCM
    Sep 14, 2012 at 0:41

1 Answer 1


Such generic claims encompassing so many mental diseases looks preposterous and fraudulent on face of it but I don't think there is or would be any scientific study which can refute all such claims, because it is easy to theorize and difficult to refute all such claims.

That said there seems to be very good link between microbes in our body and how we react and behave and eventually it may be true that to some level gut flora affects our mental health.

A 2005 paper Differences between the gut micro-flora of children with autistic spectrum disorders and that of healthy children

A new scientist article Gut bacteria may contribute to autism there are many other articles on New scientist related to gut flora an dhow it affects us.

But IMO bottom line is that Human system is so complex and so less understood that any small level clinical test claiming otherwise would be a hasty conclusion.

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    Of course it may be that autism is associated with abnormal metabolism and gut behaviour. So the causality runs from the disease to the gut flora and not the reverse.
    – matt_black
    Oct 29, 2012 at 10:04
  • @matt_black, but I guess if people see changes in symptoms on changing diet, that would point in one direction rather than the other. And unless the diet is proven pathological, people don't lose anything from trying.
    – Benjol
    Oct 3, 2018 at 8:57

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