DESTRUCTION OF TOCOPHEROLS, CAROTENOIDS, AND RETINOL IN HUMAN PLASMA BY CIGARETTE-SMOKE

The mechanisms by which exposure to cigarette smoke dramatically incre ase the incidence and severity of atherosclerosis and the incidence of lung cancer, chronic obstructive airways disease, and emphysema are i ncompletely understood. Epidemiologic evidence has suggested a modifyi ng role for antioxidant micronutrients, including tocopherols and caro tenoids, in these disease processes, It has been suggested that oxidan ts in cigarette smoke could be involved. We exposed freshly obtained h uman plasma to the gas phase of cigarette smoke to assess its effects on tocopherols, carotenoids, and retinol. Exposure to cigarette smoke led to the depletion of most of the lipophilic antioxidants in 20 mL h uman plasma. The order of disappearance was lycopene > alpha-tocophero l > trans-beta-carotene > (lutein + zeaxanthin) = cryptoxanthin > gamm a-tocopherol = retinol. However, despite a substantial loss of alpha-t ocopherol, there was very little peroxidative damage to lipids, and no detectable change in the content of polyunsaturated fatty acid-rich c holesterol esters. We conclude that a wide spectrum of lipophilic micr onutrients undergo degradation when exposed to gas-phase cigarette smo ke. The relevance of these in vitro findings to possible cigarette smo ke-induced depletions of respiratory tract lipophilic antioxidants rem ains to be clarified.