Our literature review concludes that antioxidant vitamins in general and β-carotene in particular are safe. Koval contends that β-carotene is not safe when taken by smokers and asbestos workers. He supports this contention with 2 clinical trials: the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Trial,1 which exposed 14560 male smokers to 20 mg/d of β-carotene for 5 to 8 years, and the Beta-Carotene and Retinol Efficacy Trial,2 which exposed 9420 male (and a few female) smokers and asbestos workers to 30 mg/d of β-carotene over 4 years. These studies noted an 8% and 28% increase in incidence of lung cancer, respectively. While Koval also mentions 3 other clinical trials, with 138 433 patient-years of exposure to 25 to 50 mg/d of β-carotene in men and women, that observed no increase in the incidence of lung cancer, he neglected to cite a fourth large trial that demonstrated safety. The so-called Linxian
Meyers DG, Maloley PA, Weeks D. The Safety of Antioxidant Vitamins-Reply. Arch Intern Med. 1996;156(22):2627. doi:10.1001/archinte.1996.00440210158019
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