Table 1.
Results of clinical intervention trials with fruits and vegetables, showing the value of biomarkers as indicators of compliance26
| Whole-diet studies (n = 11) | Mixed fruit/vegetable studies using counseling (n = 16) | Mixed fruit/vegetable studies using food provision (n = 36) | ||||
|---|---|---|---|---|---|---|
| Measured | Reported increase | Measured | Reported increase | Measured | Reported increase | |
| Biomarker | biomaker | (% use biomarker) | biomaker | (% use biomarker) | biomaker | (% use biomarker) |
| α-Carotene | 7 | 3 (43) | 14 | 12 (86) | 21 | 16 (76) |
| β-Carotene | 7 | 4 (57) | 15 | 13 (87) | 24 | 19 (79) |
| Lycopene | 7 | 2 (29) | 12 | 4 (33) | 20 | 8 (40) |
| β-Cryptoxanthin | 7 | 1 (14) | 12 | 8 (67) | 20 | 12 (60) |
| Lutein | 4 | 3 (75) | 7 | 5 (71) | 16 | 11 (69) |
| Zeaxanthin | 2 | 1 (50) | 5 | 1 (20) | 11 | 3 (27) |
| Lutein/zeaxanthin | 3 | 2 (67) | 5 | 3 (60) | 5 | 4 (80) |
| Total carotenoids | 5 | 2 (40) | 6 | 4 (67) | 2 | 1 (50) |
| Vitamin C | 1 | 1 (100) | 10 | 6 (60) | 18 | 14 (78) |
| Urinary potassium | 1 | 1 (100 | 2 | 0 | 2 | 1 (50) |
| Flavonoids | – | – | 1 | 0 | 8 | 6 (75) |