Research in the 1990's seemed to indicate that beta-carotene supplements may increase lung cancer risk in smokers. However, a new analysis of dietary records from one of these studies led researchers to a different conclusion. Male smokers with the highest overall antioxidant intake, including beta-carotene, actually had a reduced risk of lung cancer.
In observational studies, a high intake of individual antioxidants was related to increased lung cancer risk in male smokers. However, data from many experiments suggest that there are interactions among antioxidant nutrients; therefore, consideration of multiple antioxidants simultaneously may be important in terms of assessing risk. Yale University researchers evaluated dietary records of participants in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study (ATBC). A group of over 27,000 Finnish male smokers aged 50-69 had food records analyzed along with intakes of carotenoids, flavonoids, vitamin E, selenium, and vitamin C. After evaluating the overall intake of antioxidants in this group, the conclusion differs somewhat from the original study. According to this new analysis, the men with higher overall intakes of antioxidants had lower relative risks of lung cancer, regardless of their assigned study group (beta-carotene or placebo). While researchers of the ATBC study concluded that high-dose beta-carotene supplementation may increase lung cancer risk in male smokers, these findings support the hypothesis that a combination of dietary antioxidants reduces lung cancer risk in men who smoke.
Source: Development of a Comprehensive Dietary Antioxidant Index and Application to Lung Cancer Risk in a Cohort of Male Smokers, Margaret E. Wright, Susan T. Mayne, Rachael Z. Stolzenberg-Solomon, Zhaohai Li, Pirjo Pietinen, Philip R. Taylor, Jarmo Virtamo, and Demetrius Albanes, American Journal of Epidemiology 2004 Jul 1; 160(1):68-76
