A first report in the area of putative mechanisms to explain the increase in lung cancer risk observed in heavy smokers taking high-dose supplements indicates that ferrets exposed to cigarette smoke and supplemented with β-carotene developed squamous metaplasia in their lungs as well as altered retinoid signaling (Wang et al., 1999). Another report suggests that oxidation products of tene stimulate the binding of metabolites of benzo [a] pyrene to deoxyribonucleic acid (Salgo et al., 1999). These very new data await confirmation and further development.
Although smoking may result in a need for higher intakes of dietary carotenoids to achieve optimal plasma carotenoid concentrations, caution is warranted because β-carotene supplements, but not β-carotene-rich foods, have been suggested as causing adverse effects in smokers (see “ Tolerable Upper Intake Levels ”). Thus, any recommendations need to state clearly that those who smoke, in particular, may benefit from even higher average intakes of carotenoids from foods.
Alcohol intake, like tobacco, is inversely associated with serum β-carotene and carotenoid concentrations (Brady et al., 1996; Fukao et al., 1996; Herbeth et al., 1988, 1990; Stryker et al., 1988). Brady et al. (1996) reported that higher ethanol intake was associated with a decrease in all serum carotenoids measured, with the exception of lycopene. The inverse association appears to be dose dependent as shown by the cohort study in men of Fukao et al. (1996) in Table 8-6. It should be noted that in this study, the effects of smoking and alcohol consumption independently affected serum β-carotene concentrations in men.
Persons who consume large quantities of ethanol typically consume diets that are micronutrient deficient. Therefore, as is the case for smoking, it is not clear whether the observed decrements are fully attributable to reduced intakes or also reflect metabolic consequences of chronic ethanol ingestion.
A database of values for α-carotene, β-carotene, β-cryptoxanthin, lutein plus zeaxanthin, and lycopene for 120 foods has been assembled (Mangels et al., 1993) and was recently updated and released