Reduced plasma ascorbic acid concentrations in nonsmokers regularly exposed to environmental tobacco smoke.

Oxidants in cigarette smoke accelerate metabolic turnover of ascorbic acid (AA), and thereby deplete body stores of this potent antioxidant and putative anticarcinogen in active smokers. We examined plasma AA concentrations and vitamin C intakes in nonsmokers regularly exposed to environmental tobacco smoke (ie, passive smokers; n = 44), as compared with active smokers (n = 47) and nonexposed nonsmokers (n = 50), to determine whether passive smokers also exhibit altered AA nutriture suggestive of oxidant exposure. Plasma AA concentrations in passive smokers were intermediate between those of active smokers (P = 0.0001) and nonexposed nonsmokers (P = 0.01) despite similar dietary vitamin C intakes. Hypovitaminosis C (< 23 mumol/L) was observed in 24% of active smokers and 12% of passive smokers but not in nonexposed nonsmokers. Reduced plasma AA concentrations were associated with low vitamin C intakes within smoke-exposed populations only. We conclude that chronic smoke exposure, particularly in association with low vitamin C intake, may reduce AA pools in both active and passive smokers.