Objective: We conducted a meta-analysis of randomized controlled trials to explore whether vitamin D supplementation is beneficial for symptom improvement in children with autism spectrum disorder. Methods: We systematically searched the PubMed database, EMBASE, Cochrane Library, Web of Science, Sino-Med, Wanfang Data, and China National Knowledge Infrastructure mainly up to September 2019. Using a fixed effects model, we calculated the standard mean difference with 95% confidence interval. Furthermore, we analyzed baseline serum 25-hydroxyvitamin D levels and outcome scores including the Social Responsiveness Scale and Child Autism Rating Scale scores after vitamin D supplementation. Results: There was no significant difference in baseline serum 25-hydroxyvitamin D levels among 203 children included from three studies in the meta-analysis. After vitamin D supplementation, the outcome scores in the experimental group were dramatically elevated compared with those in the control group (p = 0.03). Conclusion Vitamin D supplementation improves the typical symptoms of autism spectrum disorder, as indicated by reduced Social Responsiveness Scale and Child Autism Rating Scale scores; thus, it is beneficial for children with autism spectrum disorder.

Objective:To analyze the serum 25-hydroxyvitamin [25(OH)D] nutritional status of children with febrile seizures in Luzhou area of Sichuan Province, and the relationship of 25(OH)D with gender, age and the local season, so as to provide reference for vitamin D supplementation and prevention of febrile seizures in children in this area.Methods:One hundred and sixty-seven children diagnosed with febrile seizures in the Affiliated Hospital of Southwest Medical University from January 2015 to July 2018 were enrolled in the febrile seizures group, and 170 children aged 0-8 years who underwent health examinations in the outpatient department in the same period were included in the healthy control group.The serum total calcium, serum 25(OH)D and hemoglobin level of children with febrile seizures were analyzed.The correlation of febrile seizures with the level of serum 25 (OH)D was evaluated from the aspects of children gender, age and season.Results:(1) The serum 25(OH)D level of healthy children [(40.6±3.07) μg/L] was significantly higher than that of the children with febrile seizures [(27.18±6.68) μg/L], and the diffe-rence was statistically significant ( t=3.15, P=0.03). The serum 25(OH)D level in children with febrile seizures decreased with age.There was no deficiency found in serum total calcium and hemoglobins of all children with febrile seizures.(2) The incidence rate of febrile seizures was the highest in January (35 cases, 20.96%) and in 2-year-old toddlers (72 cases, 44.91%). Boys were significantly more susceptible to febrile seizures than girls (1.73∶1.00). (3) The serum 25(OH)D level of children with febrile seizures in the region decreased in winter and summer (27.47-30.37 μg/L), and increased in spring and autumn (31.58-35.13 μg/L). The serum 25(OH)D level of children in winter [(27.47±1.80) μg/L] was statistically significantly different from that in spring [(31.58±1.31) μg/L] and in autumn [(35.13±3.93) μg/L] (all P<0.05). The serum 25(OH)D level in children with febrile seizures were inversely proportional to the high temperature in summer [T>35 ℃, 25(OH)D<30 μg/L]. The 25(OH)D level showed a downward trend when the temperature exceeded 35 degrees Celsius.The optimum temperature for children in this area to absorb vitamin D by sun-irradiation was 25-35 ℃. Conclusions:The occurrence of febrile seizures in children of all ages in Luzhou is closely related to the deficiency of vitamin D. Two-year-old boys are prone to be attacked by febrile seizures in January of each year.In addition to winter, children, especially those over 2 years old, are advised to supply vitamin D in high temperature periods in summer when outdoor activities are reduced.