Vitamin D deficiency/insufficiency from childhood to adulthood: Insights from a sunny country

Table 1 Main reports on vitamin D deficiency in children

Prevalence	Age group	Place	Year	Ref.
In infants 0.4% - deficient (< 25 nmol/L) 33.6% - insufficient (< 75 nmol/L) 2-5 yr stage (preschool) 1.1% - deficient 68.6% - insufficient 6-11 yr (school age) 2.0% - deficient 88.3% - insufficient Adolescents 3.3% - deficient 89.6% - insufficient	1 mo-16 yr	Hangzhou, China	2012	[1]
86% - deficient (< 37 nmol/L ) 38.3% - severely deficient (< 12.5 nmol/L) 91.7% - insufficient (< 50 nmol/L)	9-12 yr	Tehran, Iran	2007-2008	[2]
66.7% - insufficient (< 75 nmol/L), 23.6% - deficient 6.2% - severely deficient (< 25 nmol/L)	6 yr (school age)	The Netherlands	2015	[72]
Obese subjects 12.7% - deficient (< 30 nmol/L) 92% - insufficient (< 75 nmol/L) Non-obese subjects 3.4% - deficient 68% - insufficient	6-16 yr	North Texas, United States	2012	[73]
34% - insufficient 62.2% - deficient	8-16 yr	Izmir, Turkey	2012	[74]
31.0% - deficient 65.0% - insufficient	7-11 yr	Zanjan, Iran	2015	[71]
55% - insufficient (< 75 nmol/L) 5% - deficient (< 25 nmol/L)	6-21 yr	Northeastern United States	2007	[55]
55% - insufficient (< 75 nmol/L) 0.8% - deficient (< 30 nmol/L)	1-3 yr	Wuxi, China	2014-2015	[75]
Age < 5 yr 52.4% - insufficiency 19% - deficiency Age > 5 and < 20 yr 79.4% - insufficiency 26.5% - deficiency	1-50 yr	Israel	2008	[86]

Worldwide prevalence of vitamin D deficiency/insufficiency in infants, children and adolescents. Vitamin D deficiency was defined as 25(OH)D levels of ≤ 25 nmol/L and vitamin D insufficiency as 25(OH)D levels of ≤ 75 nmol/L.