Vitamin D Status and Its Determinants in a Paediatric Population in Norway

Abstract

Recommendations for sufficient vitamin D intake in children were recently revised in Norway. However, optimal levels of vitamin D are still debated and knowledge on supplementation and vitamin D levels in healthy children in Norway is scarce. Therefore, we measured the plasma-concentration of 25-hydroxyvitamin D (25(OH)D) in children and adolescents attending the outpatient paediatric clinics in Innlandet Hospital Trust, Norway during two consecutive years (2015–2017). We recruited 301 children and adolescents aged 5 months to 18 years (mean 7.8, SD 4.4 years) for the study and obtained sample material for 25(OH)D measurements from 295 (98%). Information on diet, vitamin D supplementation, sun exposure, ethnicity, parental education and general health was collected by questionnaire. 25(OH)D levels were analysed and determinants for 25(OH)D were estimated by linear regression. 1.0% of the children had deficient levels (25(OH)D < 25 nmol/L) and 21.0% had insufficient levels (25–50 nmol/L). 25(OH)D levels ranging from 50 to 75 nmol/L were found among 38.3%, while 39.7% had levels above 75 nmol/L. The mean 25(OH)D level was 70.0 nmol/L (SD 23.4, range 17–142 nmol/L) with a significant seasonal variation with lowest levels in mid-winter and highest in late summer. In addition to seasonal variation independent determinants for 25(OH)D-levels were age of the child, parental ethnicity, vitamin D supplementation and soda consumption. Along with parental ethnicity other than Nordic, age was the strongest determinant of 25(OH)D, with adolescents having the lowest levels.

Low vitamin D levels among children and adolescents in an Arctic population

“…Our study demonstrated that 25(OH)D levels in students and adults aged 24–60 years were higher than in school age children. This is consistent with earlier published findings [25,30] and may be explained by the end of body growth and a more conscious approach to food choices. Nevertheless, only a quarter of adults in the study had normal levels of vitamin D.…”

“…The results demonstrate low levels of vitamin D in the Arkhangelsk population living at 64° N. These findings are in line with the results of studies in other northern countries such as Norway and Sweden [13,14,24,25]. The lowest concentrations of 25(OH)D were found in neonates, which is consistent with findings in earlier international research [26].…”

“…This study is one of only a few to examine the status of vitamin D in the population of the Russian Arctic. The results demonstrate low levels of vitamin D in the Arkhangelsk population living at 64° N. These findings are in line with the results of studies in other northern countries such as Norway and Sweden [13,14,24,25].…”

Vitamin D concentrations were often insufficient among native Norwegian adolescents and children with a non‐Western immigrant background

“…In contrast, young children tend to spend more time outdoors, benefiting from sun exposure, often with parental supervision. One Norwegian study that was published in 2020 and included in this mini review indicated that nearly 62% of young children, particularly those under 2 years old, were given vitamin D supplements 10 . This percentage was significantly higher than a previous nationwide dietary survey among Norwegian schoolchildren, conducted in 2015, where less than half reported taking vitamin D supplements 25…”

“…The headline findings from the six Norwegian papers included in this mini review were that adolescents faced a higher risk of insufficient vitamin D levels and so did children with a non‐Western immigrant background (Table 1). 8–13 A study of a healthy paediatric population, published in 2020, reported that 78% of the participants had ample 25(OH)D levels (>50 nmol/L), while 1% were deficient and 21% had inadequate levels 10 . The 1% that were deficient were all adolescents 10 .…”