Serum antioxidant micronutrients and the risk of oral leukoplakia among Japanese

A population-based case-control study was designed for the investigation of any association between serum micronutrient levels and oral leukoplakia. Out of a total of 9536 subjects over the age of 40 years who participated in the oral mucosal screening pro gramme in Tokoname city, 48 cases detected with oral leukoplakia (38 male:10 female) were recruited. For each case, four controls matched by age and sex were selected from the same cohort. We examined the fasting serum levels of retinol, alpha-tocopherol, zeaxanthin and lutein, cryptoxanthin, lycopene and carotenoids (alpha-carotene and beta-carotene) by high-performance liquid chromatography. Among males with leukoplakia mean serum lycopene and beta-carotene levels (0.175 +/- 0.202, 0.357 +/- 0.295 mu mol/l) were significantly lower than those of controls (0.257 +/- 0.252, 0.555 +/- 0.408 mu mol/l) (P < 0.05, P < 0.005). Logistic regression analysis with leukoplakia as the dependent variable showed that high serum levels of beta-carotene were related to low risk of oral leukoplakia (odds ratio 0.160, 95% C.I.: 0.029-0.866, P < 0.05). There were no significant differences in any of the serum nutrients estimated ill female subjects. Our results suggest for the first time that high serum levels of beta-carotene may provide protection against oral precancer for the Japanese male. (C) 2000 Elsevier Science Ltd. All rights reserved.