Leaky gut syndrome is a proposed condition of an altered or damaged bowel lining. The term is used by some alternative medicine practitioners, but the syndrome is not a recognized diagnosis.[1] It is hypothesized to be caused by increased permeability of the gut wall resulting from toxins, poor diet, parasites, infection, or medications.[2] The leaky gut then allows substances such as toxins, microbes, undigested food, waste, or larger than normal macromolecules to leak through an abnormally permeable gut wall. Proponents propose that these out-of-place substances affect the body directly or initiate an immune reaction.[3]
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Health care practitioners who diagnose this syndrome explain that intestinal inflammation which may originate from intestinal dysbiosis or other sources of irritation, widens the junctions between the cells of the intestinal lining, allowing endotoxins and incompletely digested particles to be partially absorbed. These are targeted by antibodies, forming immune complexes which cause a semi-infectious state and can be carried by the bloodstream to distant sites where they may stimulate the release of cytokines. Low grade fever, transient gut pain, and a sense of inability to absorb nutrients are some reported symptoms in otherwise undiagnosed patients.[4][5].
While many practitioners maintain that leaky gut syndrome is a bona fide physiological condition, the area of "gut problems" lies between conventional and alternative medicine, and includes other diagnoses such as small bowel bacterial overgrowth syndrome or small intestine bacterial overgrowth (SIBO), and yeast syndrome or systemic candidiasis, and remains controversial and scientifically unsettled.[6]
Some alternative practitioners believe that leaky gut syndrome is a possible starting point or connection with many disorders such as asthma, diabetes, autoimmune diseases like lupus, diseases like scleroderma, internal colitis, long term disorders like rheumatoid arthritis, severe illnesses like multiple sclerosis and chronic fatigue syndrome and Crohn's disease. [7]
Andrew Wakefield has proposed a condition called Autistic enterocolitis to describe a condition where bowel disorders can contribute to autism,[8]. However 10 of the 13 authors of the paper have since retracted its interpretations[9], and the British General Medical Council (GMC) has ruled that Wakefield suppressed and falsified data[10][11].
Parents have reported gastrointestinal (GI) disturbances in autistic children, and several studies have investigated possible associations between autism and the gut.[12] The disputed Wakefield et al. paper also suggested that some bowel disorders may allow antigens to pass from food into the bloodstream and then to contribute to brain dysfunction.[8] Although Wakefield later proposed the term autistic enterocolitis, his studies' methodology has been criticized, their results have not been replicated by other groups,[13] and Wakefield has been accused of manipulating patient data and misreporting results.[14]
There is no research evidence that autistic children are more likely to have GI symptoms than typical children.[12] In particular, design flaws in studies of elimination diets mean that the currently available data are inadequate to guide treatment recommendations.[15] A 2008 study found that children with autism had no more peptides in their urine than typical children, casting doubt on the proposed mechanism underlying the leaky-gut theory.[16]
In another example, a 1998 study of three children with ASD treated with secretin infusion reported improved GI function and dramatic improvement in behavior, which suggested an association between GI and brain function in autistic children, although the low number of patients is statistically insignificant.[17] After this study, many parents sought secretin treatment and a black market for the hormone developed quickly.[12] However, later studies found secretin ineffective in treating autism.[18]
Leaky gut syndrome theories inspired several dietary treatments, including gluten-free diets, casein-free diets, antifungal diets, low-sugar diets, as well as supplements that include nystatin, B12, and probiotics.
A review looked at the treatment of autism using an approach based on dietary manipulation used to alter the effects of so-called 'leaky gut'. It concluded that these treatments are cumbersome and not proven to be efficacious. [12]