TABLE 5.
Cross-sectional and longitudinal associations (linear model) of usual total iron intake with serum transferrin (g/L) and sensitivity analyses in the IDEFICS/I.Family study
| Model | Main model | Sensitivity analysis including usual vitamin C intake1 | Sensitivity analysis with usual iron intake from heme sources1 as exposure | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Wave 0 (N = 833) | |||||||||
| β estimate | β | 95% CI | β | 95% CI | β | 95% CI | |||
| Total iron intake1 (mg/d) | 0 | −0.03 | 0.03 | 0.01 | −0.02 | 0.05 | −0.02 | −0.07 | 0.02 |
| Mainly vegetarian diet2 (ref: omnivore diet) | 0.16 | −0.05 | 0.36 | 0.15 | −0.05 | 0.35 | 0.14 | −0.06 | 0.35 |
| Vitamin C intake1 (mg/d) | 0 | −0.003 | 0.0001 | ||||||
| Wave 3 (N = 1394) | |||||||||
| β estimate | β | 95% CI | β | 95% CI | β | 95% CI | |||
| Total iron intake1 (mg/d) | 0 | −0.01 | 0.02 | 0 | −0.02 | 0.02 | −0.01 | −0.06 | 0.03 |
| Mainly vegetarian diet2 (ref: omnivore diet) | 0.06 | −0.02 | 0.14 | 0.06 | −0.02 | 0.14 | 0.05 | −0.04 | 0.14 |
| Vitamin C intake1 (mg/d) | 0 | −0.001 | 0.002 | ||||||
| Longitudinal (N = 812) (i.e., at W3 adjusted for serum transferrin at W0) | |||||||||
| β estimate | β | 95% CI | β | 95% CI | β | 95% CI | |||
| Total iron intake1 (mg/d) | 0 | −0.01 | 0.02 | 0 | −0.02 | 0.02 | 0.02 | −0.03 | 0.06 |
| Mainly vegetarian diet2 (ref: omnivore diet) | 0.05 | −0.04 | 0.14 | 0.05 | −0.04 | 0.14 | 0.07 | −0.03 | 0.17 |
| Vitamin C intake1 (mg/d) | 0 | −0.001 | 0.002 | ||||||
Abbreviations: β, β estimate; CI, confidence interval; IDEFICS: Identification and Prevention of Dietary- and Lifestyle-Induced Health Effects in Children and Infants; W0, first examination wave; W3, third examination wave.
Adjusted for usual energy intake, age, BMI-z-score, sex, country and ISCED.
Usual dietary intakes of total iron, iron from heme sources and vitamin C were estimated from 24-h dietary recalls linked to food composition tables.
Children were classified as mainly vegetarian if they replied to the specific question to typically exclude meat, poultry, sausage and fish from their diet in the food frequency questionnaire. Some of them however reported later on to occasionally consume meat or fish.