With an increasing prevalence, autism spectrum disorders are neurological disorders that characterized by a number of symptoms such as significantly different attitudes in social interactions and communication, repetitive and obsessively behaviors, and inability to use motor skills. In addition, nutritional problems such as abnormal eating habits, sensitivity to food texture, selectivity in food consumption, and gastrointestinal problems are also accompanied. Besides, microbiota of patients with autism seems to be different when compared to healthy individuals. Therefore, nutritional treatment applications are essential for reducing the symptoms and to replace nutritional deficiencies. The most preferred nutritional therapies that have been shown to reduce the symptoms in autism are vitamin, mineral, and probiotic supplements, ketogenic diet, gluten-free and casein-free diets. Since nutritional treatments don’t show the same effect in every autistic child, nutritional therapy should be applied specific to the individual. This review summarizes the literature that investigate nutritional problems and the effects of current nutritional treatments in autism.