Study participant characteristics
| Nonasthmatic controls | Cases with asthma | |
| Participants | 89 | 89 |
| Males | 23 (26) | 23 (26) |
| Age | 43.0±9.9 | 42.8±9.7 |
| Social class % | ||
| 1 | 13 (14.6) | 10 (11.2) |
| 2 | 35 (39.3) | 35 (39.3) |
| 3 | 36 (40.4) | 41 (46.1) |
| 4 | 4 (4.5) | 2 (2.2) |
| 5 | 1 (1.1) | 1 (1.1) |
| Current smokers | 1 (1.1) | 0 (0) |
| Total pack-years | 1.4±3.1 | 1.3±2.9 |
| Using inhaled steroids | ||
| Beclomethasone | 0 | 64 |
| Budesonide | 0 | 18 |
| Fluticasone | 0 | 7 |
| Season seen | ||
| Winter | 7 (7.9) | 30 (33.7) |
| Spring | 50 (56.2) | 18 (20.2) |
| Summer | 19 (21.3) | 22 (24.7) |
| Autumn | 13 (14.6) | 19 (21.3) |
| Atopy | 21 (23.6) | 72 (80.9) |
| BMI kg·m−2 | 25.4±4.7 | 25.5±5.2 |
| Daily energy intake MJ | 7.9±2.2 | 8.1±2.6 |
| Daily protein intake g | 76.7±17.1 | 80.1±21.2 |
| Daily dietary vitamin C mg | 101.6±48.6 | 103.0±52.6 |
| Daily dietary magnesium mg | 332.9±102.4 | 322.6±113.3 |
Data are presented as n (%) or mean±sd
BMI: body mass index
MJ: megajoule