Autism spectrum disorder (ASD) is a developmental disorder associated with individuals' inability to verbally and nonverbally communicate with their environment. ASD is accompanied by a number of neurological problems and immune disorders and various non-neurological comorbidities such as gastrointestinal system abnormalities. Besides, various nutritional problems, such as food selectivity, food rejection, food allergies and chewing and swallowing problems can be observed in these individuals. In addition to these nutritional problems, elimination diets like gluten-free and/or casein-free diet, specific carbohydrate diet, ketogenic diet and low oxalate diet, applied for therapeutic purposes greatly affect the nutritional status in ASD. Since these diets are aimed at eliminating various nutrients from the diet depending on their content, special care should be taken to ensure that individuals receive sufficient energy and nutrients. When necessary, it may be beneficial to supplement various vitamins and minerals, antioxidants, probiotic and omega-3 fatty acids under expert control. Especially, since children with ASD have inadequate dietary antioxidant intake and highly oxidative stress, antioxidant intake must be followed meticulously. Considering all this, since the effect of nutrition in ASD is very important and there is not enough information yet, it can be said that nutritional interventions should be made depending on the symptoms of the individual with ASD. It should be kept in mind that ASD symptoms can be alleviated with nutritional interventions. In this review, various nutritional problems, different dietary treatments and supplements in individuals with ASD are explained.