Table 2.
Characteristics of female (n = 562) and male participants (n = 323). 1
| Female Participants | Male Participants | |||
| Mean 2 ± SD | n (%) | Mean2 ± SD | n (%) | |
| Age (years) | 19.4 ± 1.43 | - | 20.1 ± 1.78 | - |
| Ethnicity | ||||
| European | - | 454 (80.8) | - | 253 (78.3) |
| Māori/Pasifika | - | 16 (2.8) | - | 13 (4.0) |
| Asian | - | 56 (10.0) | - | 35 (10.8) |
| Other | - | 36 (6.4) | - | 22 (6.9) |
| Body mass indext (BMI) (kg/m2) | 23.5 ± 4.14 | - | 24.0 ± 3.6 | - |
| Alcohol intake (standard drinks/wk) 3 | 3.4 (3.0, 3.8) | - | 6.2 (5.3, 7.3) | - |
| Physical activity (minutes/day) 3 | 21.7 (19.9, 23.6) | - | 23.4 (20.4, 26.7) | - |
| Taking oral contraceptive agent | - | 267 (47.5) | - | - |
| Hemoglobin (g/L) | 133.6 ± 8.7 | - | 154.4 ± 8.9 | - |
| Serum ferritin (µg/L) 3 | 35.6 (33.4, 37.9) | - | 94.4 (88.0, 101.4) | - |
| Soluble transferrin receptor (mg/L) | 5.6 ± 1.9 | - | 5.2 ± 1.3 | - |
| C-reactive protein (CRP) (mg/L) | 1.6 ± 1.7 | - | 1.0 ± 1.3 | - |
| Alpha-1-acid glycoprotein (AGP) (g/L) | 0.6 ± 0.2 | - | 0.7 ± 0.2 | - |
| Body iron (mg/kg) | 5.4 ± 3.4 | - | 9.1 ± 2.8 | - |
| Iron deficiency anemia | - | 12 (2.1) | - | 2 (0.6) |
| Non-anemic iron deficiency | - | 33 (5.9) | - | 1 (0.3) |
| Low iron stores | - | 72 (12.8) | - | 5 (1.5) |
| Iron sufficient | - | 445 (79.2) | - | 315 (97.5) |
| Depressive symptoms 3 (CES-D 4) | 12.0 (11.3, 12.7) | - | 10.6 (9.9, 11.4) | - |
| Negative mood 3,5 | 0.6 (0.6, 0.7) | - | 0.6 (0.6, 0.7) | - |
| Positive mood 5 | 2.0 ± 0.5 | - | 2.1 ± 0.5 | - |
| Tiredness 5 | 1.8 ± 0.7 | - | 1.5 ± 0.7 | - |
| Problems concentrating 5 | 1.5 ± 0.7 | - | 1.3 ± 0.7 | - |
| Stress 5 | 1.4 ± 0.60 | - | 1.3 ± 0.6 | - |
1 Following exclusion of participants who did not meet study criteria: < 17 or > 25 years; did not complete ≥7 daily diaries; no blood sample; unable to analyze blood sample; did not complete final questionnaire; CRP ≥ 10 mg/L or AGP > 1 g/L; taking antidepressant or mood stabilizing medication; 2 Data are arithmetic mean ± standard deviation (SD) unless stated otherwise; 3 Skewed data are geometric mean (95% confidence interval); 4 Centre for Epidemiologic Studies Depression Scale (a score of 16 out of a possible 60 is considered to indicate presence of high depressive symptomatology) [30]; 5 On a 5-point scale from 0 to 4.