Following a request by the European Commission the Scientific Panel on Food Additives and Nutrient Sources added to Food (ANS) was asked to conclude on the possible link between the ingestion of β-carotene and cancer enhancement in heavy smokers.
The safety of (synthetic) β-carotene [E 160a (ii)] has been evaluated previously by JECFA (1975) en the SCF (2000a). In 2000, the SCF concluded that there were insufficient data to set a precise figure for a Tolerable Upper Intake Level (UL) of β-carotene (SCF, 2000b).
In the past, high serum β-carotene levels have been associated with a decrease in incidence of cancer, including lung cancer, in humans (Mayne, 1996; Ziegler et al., 1996). However, the ATBC study and CARET trials (ATBC Study group, 1994; Omenn et al., 1996a; 1996b; Omenn, 1998) unexpectedly revealed that heavy smokers (at least 1 package/day for 36 years on average) receiving long-term β-carotene (20 mg/day) supplementation (ATBC) or β-carotene (30 mg/day) + retinol (25 000 International Unit (IU) vitamin A) supplementation (CARET), showed increased rather than decreased incidences of lung cancer.
In 2010, Druesne-Pecollo et al. performed a meta-analysis of randomized controlled trials (RCT) investigating β-carotene supplementation and cancer risk. They found absence of any protective effect associated with β-carotene supplementation with regard to primary cancer risk. However, their analyses indicated an increased risk of lung cancers in individuals supplemented with β-carotene at dose levels equal to or greater than 20 mg/day as well as in smokers and asbestos workers supplemented with β-carotene. A statistically significant interaction was found between β-carotene intake and smoking status.
Epidemiological studies reported no increased lung cancer incidence in heavy smokers at supplemental dose levels of β-carotene varying from 6 – 15 mg/day for about 5 up to 7 years (Druesne-Pecollo et al., 2010).
The Panel concluded that exposure to β-carotene from its use as food additive and as food supplement at a level below 15 mg/day do not give rise to concerns about adverse health effects in the general population, including heavy smokers.