“This secondary analysis of a randomized clinical trial found that a higher-than-standard vitamin D3 supplementation (1200 IU daily vs 400 IU) between ages 2 weeks and 2 years reduced the risk of internalizing problems later in childhood at ages 6 to 8 years,” the researchers wrote in JAMA Network Open.
The study, led by the University of Tampere in Finland, is part of the long-term Vitamin D Intervention in Infants (VIDI) clinical trial, which set out to investigate how early vitamin D3 intervention affects children’s growth and development.
Vitamin D and neurodevelopment
Previous studies (primarily observational) suggest that lower childhood vitamin D levels are associated with autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD), as well as an increase in depressive symptoms and internalizing and externalizing problems later in childhood.
This latest trial builds on a previous subgroup analysis of the VIDI cohort, which showed that 1200 IU compared to 400 IU of vitamin D supplementation did not benefit developmental milestones or social-emotional skill acquisition in healthy term infants up to two years of age.
Because behavioral and psychiatric problems may not be fully manifested during the early years but may become more apparent as environmental demands increase, the research team extended the investigation to childhood psychiatric symptoms at ages 6 to 8 years.
“This period is characterized by increased demand for self-regulating skills, important in mitigating potential internalizing and externalizing problems, combined with a still-developing prefrontal cortex,” they noted.
This follow-up study analyzed data from 346 children (ages 6 to 8 years, 164 females) who had participated as infants in the initial VIDI intervention from 2013 to 2014. In this subgroup, 169 received 400 IU and 177 received 1200 IU of oral vitamin D3 supplementation daily from ages 2 weeks to 24 months.
Primary outcomes were internalizing, externalizing, and total problems scores, with clinically significant problems defined as T scores of 64 or greater in the Child Behavior Checklist questionnaire. As secondary outcome, the study evaluated whether the impact of supplementation differs in children of mothers with lower or higher maternal vitamin D3 levels in pregnancy.
“Clinically significant internalizing problems occurred in 10 participants in the 1200-IU group compared with 20 participants in the 400-IU group after adjustment for sex, birth season, maternal depressive symptoms at birth, and parental single status at follow-up,” the study found.
A post hoc subgroup analysis found that 48 children in the 400-IU group with maternal 25(OH)D concentrations less than 30 ng/mL had higher internalizing problems scores compared with children in the 1200 IU group, including 44 children with maternal 25(OH)D concentrations below 30 ng/mL and 91 children with maternal concentrations above 30 ng/mL. Groups did not exhibit differences in externalizing problems, such as aggressive behavior and rule-breaking, or total problems.
The researchers call for future studies to substantiate whether early life higher-dose vitamin D3 supplementation is associated with benefits for children exposed to lower pregnancy 25(OH)D levels; and to further the understanding of outcomes related to children’s somatic health, such as growth and allergies, for which lower doses were found to be more beneficial during infancy.
Source: Jama Network Open
“Effect of Vitamin D3 Supplementation in the First 2 Years of Life on Psychiatric Symptoms at Ages 6 to 8 Years”
Authors: Samuel Sandboge et al.