Table 2.
Comparison of participants’ characteristics by sex and vitamin D status: adolescents (n 2062; 1095 boys, 967 girls) aged 10–18 years, Korean National Health and Nutrition Examination Survey (KNHANES) 2008–2009
| Boys | Girls | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Serum 25(OH)D (nmol/l) | Serum 25(OH)D (nmol/l) | |||||||||
| <27·5 | ≥ 27·5 | <27·5 | ≥ 27·5 | |||||||
| Mean or % | sd | Mean or % | sd | P value | Mean or % | sd | Mean or % | sd | P value | |
| Age* (%) | <0·0001 | <0·0001 | ||||||||
| Elementary school | 13·3 | 38·4 | 18·1 | 39·1 | ||||||
| Junior high school | 39·8 | 36·0 | 36·9 | 36·4 | ||||||
| Senior high school | 46·9 | 25·6 | 45·0 | 24·5 | ||||||
| Season† (%) | <0·0001 | <0·0001 | ||||||||
| Winter | 40·6 | 22·6 | 42·9 | 22·6 | ||||||
| Spring | 43·0 | 20·2 | 40·3 | 18·7 | ||||||
| Summer | 7·0 | 28·8 | 7·4 | 32·4 | ||||||
| Autumn | 9·4 | 28·4 | 9·4 | 26·3 | ||||||
| Obesity level‡ (%) | 0·9835 | 0·1137 | ||||||||
| Normal weight | 84·9 | 85·5 | 88·6 | 85·1 | ||||||
| Overweight | 10·3 | 9·8 | 5·4 | 10·5 | ||||||
| Obese | 4·8 | 4·7 | 6·0 | 4·4 | ||||||
| Region§ (%) | 0·0067 | 0·1620 | ||||||||
| Urban | 78·1 | 66·2 | 70·5 | 64·6 | ||||||
| Rural | 21·9 | 33·8 | 29·5 | 35·4 | ||||||
| Sufficient Ca intake∥ (%) | 0·0314 | 0·2438 | ||||||||
| No | 96·9 | 91·1 | 90·6 | 93·3 | ||||||
| Yes | 4·4 | 8·9 | 9·4 | 6·7 | ||||||
| Daily Ca intake¶ (%RNI) | 46·8 | 31·0 | 58·4 | 36·3 | 0·0180 | 50·7 | 32·4 | 50·0 | 38·1 | 0·8264 |
| Moderate physical activity** (%) | 0·3799 | 0·0528 | ||||||||
| No | 46·2 | 41·9 | 65·7 | 56·6 | ||||||
| Yes | 53·8 | 58·1 | 34·3 | 43·3 | ||||||
| Paternal 25(OH)D (nmol/l) | 38·7 | 11·2 | 52·4 | 16·5 | <0·0001 | 43·9 | 14·5 | 55·4 | 18·2 | <0·0001 |
| Maternal 25(OH)D (nmol/l) | 31·4 | 11·7 | 41·4 | 14·2 | <0·0001 | 31·7 | 11·2 | 44·2 | 15·2 | <0·0001 |
| Paternal 25(OH)D (%) | ||||||||||
| <50 nmol/l | 86·1 | 48·9 | <0·0001 | 74·7 | 46·8 | <0·0001 | ||||
| ≥50 nmol/l | 13·9 | 51·1 | 25·3 | 53·2 | ||||||
| Maternal 25(OH)D (%) | ||||||||||
| <50 nmol/l | 96·2 | 75·1 | <0·0001 | 93·7 | 70·4 | <0·0001 | ||||
| ≥50 nmol/l | 3·8 | 24·9 | 6·4 | 29·6 | ||||||
25(OH)D, 25-hydroxyvitamin D.
*All participants were grouped as elementary school (age 10–12 years), junior high school (age 13–15 years) and senior high school (age 16–18 years) according to their age.
†Seasons are noted as spring (March to May), summer (June to August), autumn (September to November) and winter (December to February).
‡Obesity level was determined according to the age- and sex-specific BMI percentile(9): normal weight (BMI <85th percentile), overweight (BMI ≥85th percentile and <95th percentile) and obese (BMI ≥95th percentile).
§Regions were grouped as rural areas (Gangwon, Chungbuk, Chungnam, Jeonbuk, Jeonnam, Gyeongbuk, Gyeongnam and Jeju) and urban areas (Seoul, Gyeonggi, Busan, Daegu, Incheon, Gwangju, Daejeon and Ulsan).
∥Sufficient Ca intake was indicated as ‘yes’ when daily Ca intake of the participants was equal to or greater than the Recommended Daily Allowance(10).
¶Daily Ca intake was presented as a percentage of the Recommended Nutrient Intake (%RNI) for Koreans(10).
**Moderate physical activity was indicated as ‘yes’ when the participant engaged in moderate-intensity physical activity for more than 20 min at a time and more than 3 times/week.