Previous studies on the associations between dietary antioxidant vitamins and the risk of cervical cancer remain inconsistent, and little evidence is available for serum antioxidant vitamins, which provide more accurate measurements of these nutrients. We conducted a case-control study of 458 incident cases with invasive cervical cancer and 742 controls to assess the effects of diet or serum antioxidant vitamins. Higher serum antioxidant vitamins were associated with a lower risk of cervical cancer after adjusting for potential confounders. The odds ratios (ORs) for the highest (vs. lowest) quartile were 0.66 (95% confidence interval [CI] = 0.46-0.93; P = 0.024) for α-carotene, 0.63 (95% CI = 0.45-0.90; P = 0.006) for β-carotene, 0.53 (95% CI = 0.37-0.74; P < 0.001) for vitamin E, and 0.48 (95% CI = 0.33-0.69; P < 0.001) for vitamin C. Dietary intakes of vitamins E and C were inversely associated with the risk of cervical cancer. Risk of cervical cancer from serum antioxidant vitamins was more evident in passive smokers than non-passive smokers. These findings indicated that antioxidant vitamins (mainly α-carotene, β-carotene, and vitamins E and C) might be beneficial in reducing the risk of invasive cervical cancer in Chinese women, especially in passive smokers.

Antioxidants may protect against oxidative stress, which is associated with tuberculosis disease. However, direct evidence for the protective association between dietary antioxidants and tuberculosis incidence in humans has been lacking. The relation between intake of antioxidant vitamins (A, C, D, E) and individual carotenoids (α-carotene, β-carotene, β-cryptoxanthin, lycopene, lutein) and tuberculosis incidence was examined in the Singapore Chinese Health Study, a prospective cohort of 63,257 adults 45-74 years old enrolled during 1993-1998. Baseline intake of these antioxidants was estimated using a validated semi-quantitative food-frequency questionnaire including use of dietary supplements. After an average of 16.9 years follow-up, 1,186 incident active tuberculosis cases were identified among cohort participants. Compared to the lowest quartile, reduced active tuberculosis risk was observed for the highest quartile of vitamin A (hazard ratio = 0.71, 95% confidence interval: 0.59-0.85; P-trend < 0.01) and β-carotene (hazard ratio = 0.76, 95% confidence interval: 0.63-0.91; P-trend < 0.01), regardless of smoking status. Lower tuberculosis risk was seen for vitamin C among current smokers only. Other vitamins and carotenoids were not associated with tuberculosis risk. These results suggest vitamin C may reduce tuberculosis risk among current smokers by ameliorating oxidative stress, while vitamin A and β-carotene may have additional anti-mycobacterial properties.

A new conception of the action mechanisms of vitamins and some other compounds without a vitamin status is briefly presented. It is based on results obtained through pulse radiolysis, molecular radiation biological investigations, and in vitro studies. The data clearly show that antioxidant vitamins (C, E, β-carotene) and B vitamins and related compounds possess the capability to emit"solvated electrons"in aqueous solutions or polar media. In consequence, the well-known vitamin effects are attributed to the action of the emitted solvated electrons and the resulting vitamin free radicals rather than the vitamin molecules per se, as generally accepted.