RESUMO
OBJECTIVE: To explore whether the intake of dietary carotenoids could protect against skeletal fluorosis in Guizhou province in which coal-burning fluorosis is endemic. METHODS: A case-control study of 196 patients with skeletal fluorosis and 196 age and gender-matched controls was conducted in Zhijin, Guizhou Province. Face-to-face interviews were conducted to assess habitual dietary intake using a 75-item food frequency questionnaire and various covariates with structured questionnaires. Urinary fluoride was measured using an ion-selective electrode method. The genotype of superoxide dismutase 2 (SOD2) rs11968525 was detected by TaqMan method. RESULTS: We observed significant dose-dependent inverse associations of skeletal fluorosis with intake of ß-carotene, lutein/zeaxanthin, lycopene, and total carotenoids (P-trend = 0.002 to 0.018), whereas α-carotene and ß-cryptoxanthin intakes were not found to be related to skeletal fluorosis, after adjustment for potential confounders. The adjusted ORs and 95% CI of skeletal fluorosis for the highest versus lowest quartile were 0.30 (0.10, 0.86) for ß-carotene, 0.23 (0.08, 0.66) for lycopene, 0.26 (0.10, 0.75) for lutein/zeaxanthin and 0.34 (0.14, 0.74) for total carotenoids (all P-trend < 0.05). Stratified analyses showed that the protective effects of lutein/zeaxanthin and total carotenoids on skeletal fluorosis were more evident for individuals with the AG+AA genotypes of SOD2 (rs11968525). CONCLUSION: Increased intakes of ß-carotene, lutein/zeaxanthin, lycopene, and total carotenoids are independently associated with a lower risk of coal-burning skeletal fluorosis. SOD2 (rs11968525) polymorphisms might modify the inverse associations between dietary carotenoids and skeletal fluorosis.