Antioxidant vitamin supplementation reduces benzo(a)pyrene-DNA adducts and potential cancer risk in female smokers.

Study answer

What this study found

Overall, vitamin C and E did not significantly reduce B(a)P-DNA adducts (14% reduction; P=0.19). In women, adducts were 31% lower in the vitamin group after adjusting for pretreatment adducts and cotinine (P=0.04); among GSTM1-null women, reduction was 43% (P=0.04). No significant effect in men or GSTM1-normal groups. Implication: antioxidant vitamins may reduce tobacco-related DNA damage in female smokers, especially GSTM1-null, but findings are not conclusive for clinical cancer risk; smoking cessation remains the primary strategy to lower cancer risk; confirmatory studies are needed.

Study & population

Population: adults >18 years who smoked ≥10 cigarettes per day; both genders; no history of cancer or liver disease; not taking vitamin supplements; cotinine >25 ng/mL at baseline.

Intervention

Daily intake of a combination pill containing vitamin C 500 mg and vitamin E 400 IU for 15 months; one pill taken daily.

Key limitation

Small subgroup sample sizes (women, GSTM1-null); 15-month follow-up with 176/284 completers; DNA adducts measured in peripheral blood leukocytes rather than lung tissue; potential selection bias due to dropout; limited generalizability to low-income smoker populations; cancer outcomes not assessed.

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Original abstract