Pediatr Gastroenterol Hepatol Nutr.  2021 Mar;24(2):207-217. 10.5223/pghn.2021.24.2.207.

Seasonal Changes in Vitamin D Levels of Healthy Children in Mid-Latitude, Asian Urban Area

• Won JW
• Jung SK
• Jung IA
• Lee Y

• KMID: 2513664
• DOI: http://doi.org/10.5223/pghn.2021.24.2.207

Abstract

Purpose
This study aimed to investigate the seasonal changes in vitamin D levels in a healthy pediatric population living in mid-latitude East Asian urban areas.
Methods
A pediatric population was selected from single secondary hospital visitors. Clinical data and serum vitamin D levels were collected retrospectively. Statistical analyses were performed based on the month of the blood sampling date, subject age, and vitamin D supplementation history. The data were categorized into three subgroups based on serum vitamin D levels—adequate (≥30 ng/mL), insufficient (20–29 ng/mL), and deficient (<20 ng/mL).
Results
Of the 481 patients, 172 had vitamin D supplementation history. More than 70% of the total study population had inadequate vitamin D levels (<30 ng/mL). The non-supplemented group and the supplemented group showed significantly uneven monthly distribution of the adequate, insufficient, and deficient subgroups. Only the nonsupplemented group showed significantly different average vitamin D levels in the summer months compared to the winter months. In the non-supplemented group, vitamin D levels were the lowest in March, the highest in August and September. Significant relevance was noted between vitamin D supplementation status and vitamin D serum level in February and March. There was no significant difference between different age groups in terms of the distribution of vitamin D levels.
Conclusion
Currently-widespread vitamin D replacement methods seem to have some effect on increasing the overall serum vitamin D levels, specifically during late winter when natural serum vitamin D levels plunge. However, they are unable to fully compensate the seasonal fluctuation.

Keyword

Vitamin D; Calcitriol; Vitamin D deficiency; Seasons; Infant; Child