Autism spectrum disorders (ASDs) are characterized by difficulties with reciprocal social interactions, deficiency in verbal and non-verbal communication, and restricted, repetitive and stereotyped patterns of behavior and interest; one of these characteristic behaviors is food selectivity. The objective of this study was to perform a systematic review of the literature published between 1970 and 2013 concerning this eating behavior. The articles identified were analyzed in terms of: sample size, study design, and criteria for assessment and intervention, as well as the results, level of evidence and grade of recommendation.The main search was conducted in Medline, although other databases were also consulted (Cochrane Library, Scielo, ScienceDirect and Embase). Regarding the methodological quality of the articles retrieved, almost all had limited statistical validity for some of the following reasons: lack of a control group and/or definitions of inclusion criteria, analysis being based on single individuals, heterogeneous groups including different ages, small sample sizes, or failure to consider phenotypic variability between individuals or alternative explanations, as well as multiple meanings being applied to the term "food selectivity". Despite all this, there is empirical evidence and an overall scientific consensus supporting an association between food selectivity and ASDs.

In autism spectrum disorders, many parents resort to alternative treatments and these are generally perceived as risk free. Among these, the most commonly used is the gluten-free casein-free diet. The objective of this work was to conduct a systematic review of studies published from 1970 to date related to the gluten-free casein-free diet in autism spectrum disorders patients. Few studies can be regarded as providing sound scientific evidence since they were blinded randomised controlled trials, and even these were based on small sample sizes, reducing their validity. We observed that the evidence on this topic is currently limited and weak. We recommend that it should be only used after the diagnosis of an intolerance or allergy to foods containing the allergens excluded in gluten-free casein-free diets. Future research should be based on this type of design, but with larger sample sizes.

Children with autism spectrum disorder (ASD) have problems of food selectivity, implying risks of nutritional deficiencies. The aim was to compare intakes of macro and micronutrients and body mass index in ASD and typically developing (TD) children. In a case-control study, 3-day food diaries and anthropometric measurements were completed for ASD (n = 40) and TD (n = 113) children (aged 6-10 years) living in the same area. Body mass indices were below the 5th percentile in 20 % of ASD versus 8.85% of TD children. We found intakes were lower for fluoride (p = 0.017) and higher for vitamin E (p = 0.001). There was limited food variety and inadequacy of some intakes suggests that routine monitoring of ASD children should include assessment of their dietary habits, as well as anthropometric measurements.

This case-control study investigated nutrient intake, healthy eating index with 10 items on foods and nutrients, on 3-day food diaries and anthropometric measurements in 105 children with autism spectrum disorder and 495 typically developing children (6-9 years) in Valencia (Spain). Children with autism spectrum disorder were at a higher risk for underweight, eating more legumes, vegetables, fiber, and some micronutrients (traditional Mediterranean diet) but fewer dairy and cereal products, and less iodine, sodium, and calcium than their typically developing peers. Differences existed in total energy intake but healthy eating index and food variety score differences were not significant. Autism spectrum disorder group failed to meet dietary recommendations for thiamin, riboflavin, vitamin C, or calcium. Risk of inadequate intake of fiber, vitamin E, and sodium was lower in children with autism spectrum disorder than typically developing children. Results suggest that (1) risk of inadequate intake of some micronutrients in children with autism spectrum disorder and (2) cultural patterns and environment may influence food intake and anthropometric characteristics in autism spectrum disorder. Primary care should include anthropometric and nutritional surveillance in this population to identify intervention on a case-by-case basis. Future research should explore dietary patterns and anthropometric characteristics in different autism spectrum disorder populations in other countries, enhancing our understanding of the disorder's impact.