25-Hydroxyvitamin D levels among 2-year-old children: findings from the Japan environment and Children’s study (JECS)

Abstract

Background The study aim was to obtain epidemiological data on vitamin D levels for the pediatric population in Japan. We assessed the prevalence of vitamin D deficiency and insufficiency in 2-year-old Japanese children using data from a large ongoing birth cohort study. Methods Data for analysis was obtained from the Japan Environment and Children’s Study (JECS) and a Sub-Cohort Study (SCS) of JECS. We evaluated the children’s serum 25(OH) D levels by 5th, 10th, 25th, 50th, 75th, 90th, and 95th percentiles, and the rates of vitamin D deficiency or insufficiency. We also presented a weighted prevalence rate for vitamin D deficiency or insufficiency among all children in JECS. Results After excluding children with missing 25(OH)D2 or 25(OH)D3 data, we analyzed 4655 remaining children, of whom 24.7% (95% CI, 23.5–26.0%) had vitamin D deficiency (< 20 ng/mL), and 51.3% (95% CI, 49.8–52.7%) were at risk of vitamin D insufficiency (20–30 ng/mL). The estimated prevalence of vitamin D deficiency and insufficiency among all children in JECS were 25.4% (95% CI, 24.1–26.7%) and 50.9% (95% CI, 49.4–52.4%). Vitamin D deficiency was found in 22.9% of boys and 26.5% of girls. Median serum 25(OH) D concentrations were lower among participants measured during winter and spring than among those measured in summer and autumn. The highest rate of vitamin D deficiency was observed in Hokkaido, the northernmost prefecture of Japan. Conclusion We analyzed data on serum 25(OH) D levels from a birth cohort study and found that vitamin D deficiency and insufficiency are very common among 2-year-old Japanese children. Sex, season, and latitude affect serum 25(OH) D concentrations.

Smoking Exposure Is Associated with Serum Vitamin D Deficiency in Children: Evidence from the Japan Environment and Children’s Study

“…Second, serum VD status was evaluated according to a single blood test, which may not reflect long-term VD in the body very well [ 20 , 21 ]. Third, a value of 25(OH)D was truncated as 4 in this study if a value of serum 25(OH)D2 or 25(OH)D3 was lower than 4 ng/mL, which may cause an overestimation of VD level [ 18 , 20 ]. Fourth, the information on tobacco smoke exposure was collected from the questionnaires, which may underreport smoking and could not reflect the precise degree of exposure to tobacco overall.…”

“…Serum 25(OH)D concentration was measured by the liquid chromatography–tandem mass spectrometry (LC-MS/MS) method (LSI Medience Corporation, Tokyo, Japan) [ 18 ]. The intra-assay and inter-assay CV are described in our previous published study [ 18 ]. Serum 25(OH)D concentrations were defined as a sum of 25(OH)D2 and 25(OH)D3.…”

“…Serum 25(OH)D concentrations were defined as a sum of 25(OH)D2 and 25(OH)D3. Serum 25(OH)D concentrations less than 20 ng/mL were defined as VDD based on criteria published by the Japanese Society for Bone and Mineral Research [ 18 ].…”

Vitamin D deficiency associated with neurodevelopmental problems in 2‐year‐old Japanese boys

“…Large‐scale studies about vitamin D deficiency and its possible association with health problems are particularly critical in Japan. Unlike some other developed countries such as the United States, Canada, Sweden, Finland, and Norway, the Japanese government does not systematically recommend fortifying food with vitamin D nor has it encouraged supplementation 13,14 . The aim of the present study was to investigate the association between child serum 25(OH)D levels [25(OH)D3 + 25(OH)D2], and children's neurodevelopment at age two, by using data from 4653 participants of a subcohort study of the Japan Environment and Children's Study (JECS), one of the world's largest ongoing birth cohort studies 13,15–17 …”

“…Unlike some other developed countries such as the United States, Canada, Sweden, Finland, and Norway, the Japanese government does not systematically recommend fortifying food with vitamin D nor has it encouraged supplementation. 13,14 The aim of the present study was to investigate the association between child serum 25 were randomly selected from all 15 JECS Regional Centres with the following inclusion criteria: children born on 1 April 2013 through 31 December 2014, and no questionnaires, medical records, or biospecimens were missing, except for umbilical cord blood in some cases. 15 Of the 10 302 children selected, 5017 participated in the subcohort study with written consent.…”