Table 3.
Calculated intakes of energy and nutrients from the 4‐day food diary (FD) and independent measures (activity registration and biomarkers in plasma and urine) by the MoBa food frequency questionnaire (FFQ) quintiles
| Nutrient | Correctly classified (%) | Grossly misclassified (%) | Levels in quintiles of the MoBa FFQ (mean ± SD) | Q1 vs. Q5 P‐value † | P for trend ‡ | ||||
|---|---|---|---|---|---|---|---|---|---|
| Q1 (n = 23) | Q2 (n = 24) | Q3 (n = 24) | Q4 (n = 24) | Q5 (n = 24) | |||||
| Energy | |||||||||
| Intake from FD (kJ day−1) | 66 | 13 | 8408 ± 1 365 | 8791 ± 1595 | 9387 ± 1 091 | 9178 ± 1412 | 9322 ± 1 173 | <0.001 | 0.012 |
| Energy expenditure (kJ day−1) | 58 | 17 | 10 100 ± 1 098 | 9507 ± 829 | 10 344 ± 1 325 | 9995 ± 740 | 10 203 ± 883 | 0.575 | 0.248 |
| Protein | |||||||||
| Intake from FD (g day−1) | 62 | 13 | 78 ± 13 | 79 ± 15 | 78 ± 11 | 87 ± 14 | 89 ± 15 | 0.028 | 0.001 |
| Urinary protein (g per 24 h) | 59 | 11 | 79 ± 12 | 74 ± 15 | 78 ± 17 | 89 ± 16 | 89 ± 17 | 0.038 | 0.001 |
| Vitamin D* | |||||||||
| Intake from FD (μg day−1) | 71 | 0 | 4.6 ± 2.6 | 5.5 ± 3.7 | 7.6 ± 6.2 | 9.6 ± 4.6 | 11.6 ± 5.0 | <0.001 | <0.001 |
| Plasma 25(OH)D (nmol l−1) | 61 | 4 | 60.6 ± 22.4 | 62.7 ± 27.0 | 67.7 ± 28.2 | 77.0 ± 24.8 | 80.0 ± 19.7 | 0.003 | 0.001 |
| Dietary folate equivalents* | |||||||||
| Intake from FD (μg day−1) | 61 | 4 | 175 ± 75 | 247 ± 141 | 271 ± 128 | 303 ± 162 | 331 ± 204 | <0.001 | <0.001 |
| Serum folate (nmol l−1) | 62 | 11 | 19.2 ± 6.3 | 24.1 ± 11.4 | 24.1 ± 8.8 | 24.3 ± 8.8 | 24.9 ± 8.5 | 0.004 | 0.054 |
| Iodine* | |||||||||
| Intake from FD (μg day−1) | 67 | 2 | 97 ± 52 | 126 ± 55 | 131 ± 48 | 148 ± 62 | 183 ± 61 | <0.001 | <0.001 |
| Urinary iodine (μg per 24 h) | 63 | 4 | 91 ± 59 | 156 ± 91 | 175 ± 106 | 172 ± 106 | 208 ± 80 | <0.001 | <0.001 |
Correctly classified if classified into same or adjacent quintiles, grossly misclassified if classified into opposing quintiles. *Including dietary supplements. †Mann–Whitney U‐test. ‡Linear trend.