Autism and nutrition: the role of the gut–brain axis

Abstract

Autism spectrum disorder (ASD) is characterised by deficits in the ability to socialise, communicate and use imagination, and displays of stereotypical behaviour. It is widely accepted that ASD involves a disorder in brain development. However, the real causes of the neurodevelopmental disorders associated with ASD are not clear. In this respect, it has been found that a majority of children with ASD display gastrointestinal symptoms, and an increased intestinal permeability. Moreover, large differences in microbiotic composition between ASD patients and controls have been reported. Therefore, nutrition-related factors have been hypothesised to play a causal role in the aetiology of ASD and its symptoms. Through a review of the literature, it was found that abnormalities in carbohydrate digestion and absorption could explain some of the gastrointestinal problems observed in a subset of ASD patients, although their role in the neurological and behavioural problems remains uncertain. In addition, the relationship between an improved gut health and a reduction of symptoms in some patients was evaluated. Recent trials involving gluten-free diets, casein-free diets, and pre-and probiotic, and multivitamin supplementation show contradictive but promising results. It can be concluded that nutrition and other environmental influences might trigger an unstable base of genetic predisposition, which may lead to the development of autism, at least in a subset of ASD patients. Clear directions for further research to improve diagnosis and treatment for the different subsets of the disorder are provided.

Microbiota–Gut–Brain Axis: Yeast Species Isolated from Stool Samples of Children with Suspected or Diagnosed Autism Spectrum Disorders and In Vitro Susceptibility Against Nystatin and Fluconazole

“…Recently, accumulating evidence suggests that gut microbiota can influence behavior by regulating brain chemistry [22][23][24][25] and the microbiota-gut-brain axis'' became one of the major topics of research interest [6,8]. Although recent few studies revealed that human gut microbiome differs among individuals in correlation with diet, age, antibiotic usage, and underlying conditions [26][27][28][29], up to 60 % of healthy people are thought as asymptomatic carriers of Candida spp.…”

Ketogenic diet modifies the gut microbiota in a murine model of autism spectrum disorder

“…Research investigating both brain and gut function has demonstrated that both tissues have various degrees of involvement in ASD progression [5, 9]. A recent unifying theory termed the “gut-brain axis” outlines the interactions between the brain and microbiome, suggesting a possible connection in ASD [9, 10].…”

“…A recent unifying theory termed the “gut-brain axis” outlines the interactions between the brain and microbiome, suggesting a possible connection in ASD [9, 10]. This research proposes that disruption to gut microbiota composition or diversity can modulate behavior and neural biochemistry.…”

Fermented Food Guidelines for Children

“…Many processes in the gut and nervous systems may be interconnected. Previous research has suggested that some, perhaps many, children with autism have abnormal communities of digestive bacteria in their intestines 10 .…”