Autistic children often consume less varied diets, experience sleep difficulties, and have higher rates of mental health problems as compared to neurotypical peers. Yet, the direct relationship between all of these domains is not well characterized. We leveraged the Adolescent Brain Cognitive Development study (ABCD study) dataset to explore whether estimated levels of consumption of specific macro- and micronutrients correlated with the severity of mental health and sleep problems in autistic youth. We found that low vitamin B3, B6, C, and iron intake was associated with more severe psychiatric problems in autistic children in the ABCD cohort, though these findings did not reach statistical significance after correction for multiple comparisons. In a post hoc analysis, we found that the severity of sleep difficulties was correlated with estimated levels of Vitamins B3, B6, C, and iron intake and with the severity of anxiety/depressive symptoms and/or thought problems. Our analysis on a large number of nutrients, psychiatric symptoms, and sleep serves as an exploratory, initial analysis to identify specific nutrients and psychiatric symptoms that could be the focus of future (confirmatory) studies on the relationship between nutrition, sleep, and mental health in autistic individuals.