In a study involving 70 children with autism, on average 5.3 years of age, and 42 age-matched healthy controls of the same socioeconomic status, significantly lower 25(OH)D levels, 1,25(OH)(2)D levels, and calcium levels, were found in children with autism, as compared to controls. A positive association was found between levels of 25(OH)D and calcium, in children with autism. The authors conclude, "Serum values of 25(OH)D in the children with autism of this study could classify them as being "vitamin D inadequate," which lends support to the hypothesis that autism is a vitamin D deficiency disorder."