Table 1.
Basic characteristics of participants: schoolchildren aged 7–11 years from Guangzhou, China, 2014–2015 (n 5295)
| Overall (n 5295) | Boys (n 2866) | Girls (n 2429) | |||||
|---|---|---|---|---|---|---|---|
| Variable | Mean or /% | sd | Mean or % | sd | Mean or % | sd | P value |
| Age (years) | 8·8 | 1·4 | 8·8 | 1·4 | 8·8 | 1·4 | 0·992 |
| Anthropometry | |||||||
| Weight (kg) | 31·6 | 9·3 | 32·4 | 9·4 | 30·7 | 9·1 | <0·001* |
| Height (cm) | 136·4 | 10·3 | 136·2 | 9·8 | 136·6 | 10·8 | 0·002* |
| BMI (kg/m2) | 16·7 | 3·1 | 17·2 | 3·2 | 16·1 | 2·9 | <0·001* |
| BMI category | |||||||
| Normal | 70·0 | – | 64·8 | – | 76·2 | – | <0·001* |
| Overweight | 14·0 | – | 16·9 | – | 10·6 | – | <0·001* |
| Obesity | 8·8 | – | 12·7 | – | 4·1 | – | <0·001* |
| Thinness | 7·2 | – | 5·6 | – | 9·1 | – | <0·001* |
| Questionnaire | |||||||
| Fruit intake (servings/week) | 9·1 | 8·3 | 8·7 | 8·1 | 9·6 | 8·4 | 0·001* |
| Meat intake (servings/week) | 12·2 | 10·9 | 13·1 | 11·4 | 11·2 | 10·1 | <0·001* |
| Moderate-intensity PA (h/week) | 3·8 | 4·4 | 3·8 | 4·5 | 3·8 | 4·3 | 0·845 |
| Birth weight | |||||||
| Normal birth weight | 90·2 | – | 89·1 | – | 91·3 | – | <0·001* |
| Low birth weight | 5·4 | – | 4·8 | – | 6·0 | – | 0·026* |
| High birth weight | 4·4 | – | 6·1 | – | 2·7 | – | <0·001* |
| Fe metabolism parameters | |||||||
| Hb (g/l) | 128·1 | 8·5 | 128·4 | 8·5 | 127·7 | 8·5 | 0·005* |
| SF (ng/ml) | 72·6 | 32·1 | 73·2 | 34·2 | 71·8 | 29·3 | 0·110 |
| SI (μmol/l) | 16·7 | 5·3 | 16·3 | 5·3 | 17·1 | 5·2 | <0·001* |
| TIBC (μmol/l) | 60·0 | 6·7 | 60·4 | 6·6 | 59·7 | 6·9 | <0·001* |
| TS (%) | 28·0 | 9·2 | 27·1 | 9·1 | 29·0 | 9·2 | <0·001* |
PA, physical activity; SF, serum ferritin; SI, serum Fe; TIBC, total Fe-binding capacity; TS, transferrin saturation.
Data are presented as mean and standard deviation or as percentage.
BMI categories were defined by BMI Z-scores as proposed by WHO in 2007(17).
Fruit intake and meat intake were described by the number of servings in the past 7 d. Moderate-intensity PA was described by the time spent on moderate-intensity PA in the past 7 d.
Birth weight was categorized into low birth weight, normal birth weight and high birth weight according to the International Classification of Diseases, 11th Revision (ICD-11), proposed by WHO in 2018(18).
P < 0·05, boys v. girls, assessed by one-way ANOVA.