Am J C/in Nutr 1996;63:559-65. Printed in USA. © 1996 American Society for Clinical Nutrition 559 Destruction of tocopherols, carotenoids, and retinol in human plasma by cigarette smoke

ABSTRACT The mechanisms by which exposure to cigarette smoke dramatically increase the incidence and severity of athero-sclerosis and the incidence of lung cancer, chronic obstructive airways disease, and emphysema are incompletely understood. Epidemiologic evidence has suggested a modifying role for anti-oxidant micronutrients, including tocopherols and carotenoids, in these disease processes. It has been suggested that oxidants in cigarette smoke could be involved. We exposed freshly obtained human plasma to the gas phase of cigarette smoke to assess its effects on tocopherols, carotenoids, and retinol. Exposure to cig-arette smoke led to the depletion of most of the lipophilic antioxi-dants in 20 mL human plasma. The order of disappearance was lycopene> a-tocopherol> trans-/3-carotene> (lutein + zeax-anthin) = cryptoxanthin>-y-tocopherol = retinol. However, despite a substantial loss of a-tocopherol, there was very little peroxidative damage to lipids, and no detectable change in the content of polyunsaturated fatty acid-rich cholesterol esters. We conclude that a wide spectrum of lipophilic micronutrients un-dergo degradation when exposed to gas-phase cigarette smoke. The relevance of these in vitro findings to possible cigarette smoke-induced depletions of respiratory tract lipophilic antioxi-dants remains to be clarified. Am J Clin Nutr 1996;63:559-65