Table 2.
Mean values of adjusted lung function measurements across quintiles of vitamin A, carotene and vitamin C intake
| Q1 | Q2 | Q3 | Q4 | Q5 | Difference between Q5 and Q1 (95% CI) | P values for trend | |
| Vitamin A | |||||||
| Mean intake (μg RE) | 151.2 | 353.6 | 573.1 | 893.9 | 2140.8 | ||
| FEV1 (mL) | 2379 | 2389 | 2410 | 2397 | 2409 | 30 (10 to 50) | 0.008 |
| FVC (mL) | 3119 | 3136 | 3158 | 3148 | 3152 | 33 (10 to 57) | 0.007 |
| Predicted FEV1 (%) | 91.37 | 91.44 | 91.91 | 91.45 | 91.94 | 0.57 (-0.08 to 1.22) | 0.185 |
| Predicted FVC (%) | 90.93 | 91.06 | 91.45 | 91.22 | 91.48 | 0.55 (0.00 to 1.10) | 0.195 |
| Carotene | |||||||
| Mean intake (μg) | 691.1 | 1747.4 | 2938.9 | 4736.1 | 11 574.1 | ||
| FEV1 (mL) | 2347 | 2363 | 2376 | 2370 | 2379 | 32 (12 to 52) | 0.010 |
| FVC (mL) | 3088 | 3117 | 3127 | 3119 | 3124 | 36 (13.59) | 0.005 |
| Predicted FEV1 (%) | 91.55 | 92.03 | 92.26 | 91.85 | 92.31 | 0.76 (0.12 to 1.39) | 0.096 |
| Predicted FVC (%) | 91.02 | 91.68 | 91.78 | 91.41 | 91.82 | 0.80 (0.26 to 1.33) | 0.015 |
| Vitamin C | |||||||
| Mean intake (mg) | 24.2 | 53.6 | 84.2 | 128.8 | 268.9 | ||
| FEV1 (mL) | 2411 | 2423 | 2436 | 2441 | 2453 | 36 (16.56) | <0.001 |
| FVC (mL) | 3117 | 3122 | 3132 | 3140 | 3154 | 35 (12.58) | 0.014 |
| Predicted FEV1 (%) | 91.3 | 91.5 | 91.9 | 91.99 | 92.21 | 0.91 (0.27 to 1.55) | 0.050 |
| Predicted FVC (%) | 91.29 | 91.33 | 91.58 | 91.77 | 92.0 | 0.71 (0.17 to 1.26) | 0.118 |
Data were adjusted for age, sex, body mass index, energy intake, number of comorbid diseases, alcohol consumption, place of residence smoking history, pack-years (smoking amount), household income and education level. P values were determined using tests for linear trends across increasing quintiles (means) of antioxidant vitamin intake.
FVC, forced vital capacity; FEV1, forced expiratory volume in 1 s; RE, retinol equivalent; Q1, lowest quintile; Q5, highest quintile.