ERYTHROCYTE VITAMIN-E AND PLASMA ASCORBATE CONCENTRATIONS IN RELATIONTO ERYTHROCYTE PEROXIDATION IN SMOKERS AND NONSMOKERS - DOSE-RESPONSETO VITAMIN-E SUPPLEMENTATION

Many human degenerative diseases involve free radical processes that n utritional antioxidants may ameliorate or prevent, but the optimum int ake of such nutrients has yet to be established. Requirement will depe nd in part on the level of exposure to exogenous and endogenous reacti ve oxygen species. Smokers incur a sustained degree of oxidant stress from both of these sources, increasing their requirements for vitamins E and C. Male smokers (n = 50) from a Scottish population with habitu ally low vitamin E and vitamin C intakes consistently had lower plasma ascorbate concentrations (P < 0.02) and greater susceptibility to hyd rogen peroxide-stimulated erythrocyte peroxidation in vitro (P < 0.001 ) than did nonsmokers (n = 50) from the same population. Erythrocyte v itamin E concentrations increased in a dose-dependent manner during 20 wk of supplementation with 70, 140, 560, and 1050 mg D-alpha-tocopher ol. In smokers each dose was associated with a significant decrease in susceptibility of erythrocytes to peroxidation (P < 0.001). However, red cells of nonsmokers receiving the 1050-mg supplement had an increa sed susceptibility to peroxidation. Moreover, prolonged supplementatio n with D-alpha-tocopherol in nonsmokers induced a decline in plasma as corbate concentration (P < 0.02) in association with an increasing ery throcyte vitamin E uptake (P < 0.001), and in nonsmokers receiving 105 0 mg, the susceptibility to peroxidation also increased (P < 0.001). T hus, vitamin E may have prooxidant activity in nonsmokers at high and prolonged intakes.