Amelia Fossetta Manatar - Samratulangi University
Plasma β-Carotene is commony used as a reliable measure of dietary fruit and vegetable intake, giving support to possibility that β-Carotene might be causative in the decrease in CVD, cancer incidence, and all causes of age-related deaths, which has been reported for diets high in fruits and vegetables (Doll and Peto, 1981). Epidemiologic studies consistently support this association. For example, a recent study on prostate cancer in younger man found that diets rich in β-Carotene were associated with a lower incidence of prostate cancer (Wu et al., 2004). The potential prevention of chronic diseases associated with oxidative damage by β-Carotene was supported by the finding that plasma β-Carotene is decreased in smokers (Fukao et al., 1996). Because of this multiple conjugated double bonds, β-Carotene is an excellent antioxidant. Unfortunately, after many studies of the antioxidant effects of β-Carotene in cell culture and in animals and human following dietary exposure, the findings are inconclusive. Furthermore, of three key clinical trials evaluating a role for supplemental β-Carotene (20 or 30 mg/day or 50 mg on alternate days) in prevention of lung cancer, two were halted early because smokers in the β-Carotene arm had a greater incidence of cancer. The third (Physicians Health Study) showed no effect of β-Carotene on lung cancer (Clarke and Armitage, 2002). The positive side to these findings has been the insight that a reevaluation is needed in the way in which epidemiologic relationships between whole-food diets and disease incidence are translated into dietary intervention studies (Greenwald, 2002). Although trials of β-Carotene supplementation and CVD have proved negative (Clarke and Armitage, 2002), there is a strong relationship between plasma carotenoids, when used as a marker for fruit and vegetable intake, and reduced risk for CVD (Hak et al., 2004). It remains to be determined if this is due to the presence of carotenoids, or wheter carotenoids, as a marker for a plant-based diet, also act as a marker for exposure to fiber or other plant-based bioactive components.
