Unlocking the multifaceted role of vitamin D, beyond its well-known impact on skeletal health, researchers have discovered its vital involvement in neurodevelopment. Intriguing experimental studies have linked vitamin D deficiency to abnormal brain development, while observational studies have indicated lower vitamin D levels in childhood associated with attention-deficit/hyperactivity disorder and autism spectrum disorder.
Furthermore, decreased vitamin D levels have been correlated with heightened depressive symptoms, as well as internalizing and externalizing problems emerging later in childhood. Interestingly, a previous randomized clinical trial failed to reveal any advantages of higher vitamin D3 supplementation in children aged two or younger regarding developmental milestones, competencies, and behavioral issues relative to standard supplementation.
Delving into the Study: In this current investigation, researchers sought to examine the effects of vitamin D3 supplementation during the crucial first two years of life on psychiatric symptoms between the ages of six and eight. This study served as a follow-up to the aforementioned trial, which initially enrolled 495 male and 492 female infants of Northern European ancestry between January 2019 and June 2014. Each child was randomly assigned to receive either 400 IU or 1,200 IU of vitamin D3 from two weeks to two years of age.
Children received a daily dosage of five drops of the supplement. Questionnaires were employed to gather parental demographic, lifestyle, and health data. Hospital records provided gestational, delivery, and child demographic data. Maternal sera samples were collected during routine follow-up visits between six and 27 gestational weeks, while child serum samples were obtained at ages one and two, with all samples analyzed for 25-hydroxyvitamin D (25(OH)D) levels.
More than 55% of families actively participated in this follow-up investigation, which commenced in November 2019. Families completed questionnaires focusing on cognitive and psychological outcomes. Psychiatric symptoms were assessed utilizing the child behavior checklist (CBCL) questionnaire, and composite scores were computed for parent-reported total, internalizing, and externalizing problems.
Analyzing the Results: The study encompassed 346 children with an average age of 7.1 years, including 177 children in the 1,200 IU vitamin D intervention arm. Remarkably, significantly higher 25(OH)D levels were observed in the 1,200 IU group at one and two years compared to the 400 IU group. Out of the total, 20 children in the 400 IU group and 10 in the 1,200 IU group exhibited clinically significant internalizing problems. Externalizing problems were reported for 16 children in each intervention arm. Moreover, nine and eight children in the 400 IU and 1,200 IU groups, respectively, faced total problems. Sensitivity analyses involving 318 children and Center for Epidemiologic Studies Depression Scale (CES-D) scores yielded similar findings.
Supplementation did not demonstrate any notable effects on total and externalizing problems. However, higher concentrations of 25(OH)D at ages one or two were associated with a reduced risk of internalizing problems and lower internalizing problem scores in the crude model. Even after adjusting for variables such as sex, maternal depressive symptoms, single parental status, and birth season, the effect of two-year 25(OH)D levels remained unchanged. However, the impact of one-year 25(OH)D levels on internalizing problem scores was somewhat diminished.
Moreover, neither one-year nor two-year 25(OH)D levels exerted any influence on total and externalizing problems. Interestingly, 96 mothers had 25(OH)D levels below 30 ng/ml. However, maternal 25(OH)D levels did not exhibit any association with psychiatric problems in children. Notably, among children with maternal concentrations of 25(OH)D below 30 ng/ml, those in the 1,200 IU treatment group had a lower risk of internalizing problems compared to those in the 400 IU arm.
Concluding Remarks: This study shed light on the prevalence of internalizing problems, revealing rates of 5.6% and 11.8% in children receiving higher and standard vitamin D supplementation, respectively. However, no significant differences were observed concerning total and externalizing problems.
Remarkably, internalizing problem scores were significantly higher among children with standard supplementation and maternal 25(OH)D levels below 30 ng/ml compared to children receiving higher supplementation, regardless of maternal 25(OH)D concentrations. Collectively, these findings highlight the potential of higher vitamin D supplementation to reduce the risk of internalizing problems between the ages of six and eight.