ceiving human milk consume 0.78 L/day on average in the first 6 months (Chapter 2); this would result in β-carotene intake levels of 8 to 163 µg/day.
β-Carotene, α-carotene, lutein and zeaxanthin, and lycopene are available as dietary supplements. There are no reliable estimates of the amount of these dietary supplements consumed by individuals in the United States or Canada.
No adverse effects other than carotenodermia have been reported from the consumption of β-carotene or other carotenoids in food. Carotenodermia is a harmless but clearly documented biological effect of high carotenoid intake. It is characterized by a yellowish discoloration of the skin that results from an elevation of carotene concentrations.
β-Carotene is used therapeutically, at extremely high doses (approximately 180 mg/day), for the treatment of erythropoietic protoporphyria, a photosensitivity disorder. No toxic side effects have been observed at these doses. There is no evidence that β-carotene or other carotenoids are teratogenic, mutagenic, or carcinogenic in long-term bioassays in experimental animals (Heywood et al., 1985). In addition, long-term supplementation with β-carotene to persons with adequate vitamin A status does not increase the concentration of serum retinol (Nierenberg et al., 1997). However, two recent clinical trials reported an increase in lung cancer associated with supplemental β-carotene in current smokers (ATBC Cancer Prevention Study Group, 1994; Omenn et al., 1996a,b). These effects are discussed below.
Lung Cancer. The Alpha-Tocopherol, Beta-Carotene (ATBC) Cancer Prevention Study showed a significantly higher incidence of lung cancer (relative risk [RR] = 1.18; 95 percent confidence interval [CI] = 1.03−1.36) and total mortality (RR = 1.08; 95 percent CI = 1.01−1.16) in current smokers supplemented with 20 mg/day β-carotene (with or without 50 mg of α-tocopherol) for 5 to 8 years