Current Vitamin D Status in Healthy Japanese Infants and Young Children

Abstract

This study aimed to characterize serum 25-hydroxyvitamin D (25OH-D) values among Japanese children aged ≤48 mo. The study included 290 healthy infants and young children aged 0-48 mo (males/females=166/124) living in Shizuoka or Tokyo. The subjects were divided into three groups by age (Low Age: 0-5, Middle Age: 6-15, High Age: 16-48 mo). The vitamin D deficient state was defined as 25OH-D <12 ng/mL, the insufficient state as 12-20 ng/mL, and the sufficient state as >20 ng/mL. The seasonal variation of serum 25OH-D levels was also analyzed. The median serum 25OH-D levels in each group were: Low Age (n=50), 19 ng/mL; Middle Age (n=94), 30 ng/mL; and High Age (n=146), 30 ng/mL. The serum 25OH-D level was significantly lower in the Low Age group than in the other groups (p<0.01). Serum 25OH-D levels in summer and autumn (n=149) were significantly higher than in winter and spring (n=141) (33 vs. 25 ng/mL, p<0.01). In the Low Age group, there was a significant difference in serum 25OH-D levels between breast-fed infants (n=26) and formula-fed or mixed-fed infants (n=19) (12 vs. 32 ng/mL, p<0.01). However, there were no significant differences in 25OH-D levels between the two season classifications in either breast-fed or formula-fed and mixed-fed infants. Although clinical symptoms were not available, more than 75% of the breast-fed infants and 14.6% of infants and young children to whom food had been introduced were defined as having a vitamin D deficient or insufficient state. Breastfeeding seems one of the contributing factor to lower serum 25 OH-D levels among infants ≤5 mo of age.

Prevalence and predictors of vitamin D deficiency in young African children

“…Previous studies of healthy young children have reported higher prevalence estimates of 13.6% in Kenya, 15.0% in Uganda, and 25.8% in Nigeria [4,8,15]. Prevalence estimates were also higher in young children from other continents, including estimates of 15% in the USA, S7 14% in Japan, and 11% in China [34][35][36]. Vitamin D deficiency is also more prevalent in northern African countries [2], and the higher vitamin D status observed in our study might be explained by differences in latitude, geography, skin pigmentation, clothing coverage, and religious and cultural practices across Africa [37].…”

“…However, a single study in Malawian pre-school children reported an increase in 25(OH)D levels with age; however, this study was small (n=21) and included infants of mothers living with HIV in Malawi [6]. Studies from high-income countries have reported an increase in 25(OH)D levels with age, but children in these studies received vitamin D supplementation or fortification [34,35,40]. In a meta-analysis of previous studies from Africa, children had higher vitamin D status than adults in African populations [2] possibly due to increased time spent outdoors.…”

<p>Effect of Pandemic-Related Confinement on Vitamin D Status Among Children Aged 0–6 Years in Guangzhou, China: A Cross-Sectional Study</p>

“…Vitamin D Status in Different Months from 2017 to 2020 Shizuoka (35.2°N, 138.4°E) and Tokyo (35.4°N, 139.4°E) and found that serum 25(OH)D levels were lower in winter and spring than in summer and autumn 20. Home confinement led to an increase in the proportion of children with vitamin D deficiency between March and June 2020 compared to the same month in previous years.…”

Vitamin D status of pregnant women and their infants in South India: VIPIS study

“…Recent study in Japan by Nakano et al also showed similar results with vitamin D levels less than 20ng/ml in 75% of the infants. 18 Study on healthy breastfed infants in Delhi (North India) showed a prevalence of 86.5%. 19 Food fortification and targeted Vitamin D supplementation policies are recommended when the public health convention or the disease burden is >20%.…”