Subjects missing information on the use of cod liver oil or multivitamin supplements in in the Nord-Trøndelag Health Study, in comparison with subjects with complete data who were included in the analysis
| Subjects with complete data | Subjects with missing data | |
| Subjects n | 16 952 | 6614 |
| Age at baseline years | 39.4±8.8 | 40.9±8.8 |
| Body mass index kg·m−2 | 25.6±3.7 | 26.0±4.0 |
| Female sex | 9421 (55.6) | 3648 (55.2) |
| Current smoking | 4640 (28.9) | 2124 (33.8) |
| Physical activity <1 h per week | 3702 (24.2) | 1632 (27.8) |
| Education <10 years | 3082 (18.3) | 1611 (24.7) |
| Social benefit recipients | 3069 (19.3) | 1005 (32.0) |
| Having economic difficulty | 5310 (31.7) | 1164 (34.8) |
| Family history of asthma | 2824 (17.7) | 614 (11.5) |
Data are presented as mean±sd or n (%), unless otherwise stated.