Table 2.
β-Carotene supplementation trials.
| Studies | Study Designs | Ref. No. | |||
|---|---|---|---|---|---|
| Population | Intervention | Duration | Cancer outcome | ||
| ATBC | 29,133 Finish male smokers (50–69 years of age) | β-carotene, 20 mg/day; vitamin E, 50 mg/day | 5–8 years | 18% increase in lung cancer; 8% increase in mortality | 13 |
| CARET | 18,314 men and women and asbestoss workers (45–74 years of age) | β-carotene, 30 mg/day; vitamin A, 25,000 IU | <4 years | 28% increase in lung cancer; 17% increase in deaths | 15 |
| PHS | 22,071 male physicians (40–84 years of age) | β-carotene, 50 mg on alternate days | 12 years | No effect of supplementation in incidence of cancer | 14 |
| Linxian | 29,584 men and women, vitamin and mineral deficient (40–69 years of age) | β-carotene, 15 mg/day; selenium, 50 mg/day; α-tocopherol, 30 mg/day | 5 years | 13% decrease in total cancers; 9% decrease in overall deaths | 84 |
| Women’s Health Study | 39,876 female health professionals (over 45 years of age) | β-carotene, 50 mg on alternate days | 4.1 years (2.1 years’ treatment and 2.0 years’ follow-up) | No effect of supplementation in incidence of cancer | 87 |