Table 1.

Mean serum 25(OH)D concentration (nmol/l) according to demographic characteristics among Korean adolescents (n 1504) aged 12–18 years, KNHANES 2008–2009

	Unweighted n	Mean	se	P value*
Gender				<0·001
Boys	792	43·2	0·8
Girls	712	40·7	0·8
Age (years)				<0·001
12–15	959	44·1	0·8
16–18	545	39·1	0·7
Monthly income (€)				0·801
<712	126	41·1	1·6
712–2135	540	42·1	0·9
>2135	820	42·3	0·8
Alcohol drinking				0·003
Yes	150	38·7	1·3
No	1351	42·5	0·7
Smoking status				0·410
Yes	110	40·8	0·7
No	1394	42·2	1·6
Multivitamin or mineral supplement use				0·228
Yes	151	43·7	1·6
No	1353	41·9	0·7
Regular physical exercise				0·001
Yes	458	44·1	1·0
No	1040	41·1	0·7
Sleep duration (h)				0·206
<6	164	40·6	1·5
6–8	1070	41·9	0·6
>8	265	43·6	1·3

25(OH)D, 25-hydroxyvitamin D; KNHANES, Korea National Health and Nutrition Examination Survey.

*P values were obtained by Student's t test or one-way ANOVA.