title: Dietary exposures and oral precancerous lesions in Srikakulam District, Andhra Pradesh, India.
abstract: OBJECTIVE
  To test the effect of dietary nutrients on oral precancerous lesions in a reverse-smoking (i.e. smoking with the glowing end inside the mouth) population in South India.
  
  
  METHODS
  Case-control. Cases with precancerous lesions were matched to an equal number of lesion-free controls matched on age (+/- 5 years), sex and village. All subjects used tobacco in some form. Dietary data were obtained using an interviewer-administered food-frequency questionnaire, designed for use in this population. All interviews were conducted blinded to the disease status of the subject. Data were analysed using logistic regression.
  
  
  METHODS
  Nineteen rural villages in Srikakulam District, Andhra Pradesh.
  
  
  METHODS
  From a survey of 6007 tobacco users, 485 (79% women) were found to have precancerous, mostly palatal, lesions (cases), and 487 lesion-free subjects were selected as controls.
  
  
  RESULTS
  All eligible subjects consented to participate and nearly all (> 99%) had complete data for analyses. Reverse smoking was the most common form of tobacco use among cases (81.9%) and controls (73.5%), and reverse smokers were 5.19 times more likely than chewers to have these lesions (95% confidence interval = 1.35, 19.9). After controlling for relevant covariates, including the type of tobacco use, protective linear effects were observed for zinc (70% reduction across the interquartile range, P < 0.002), calcium (34% reduction, P < 0.002), fibre (30% reduction, P < 0.009), riboflavin (22% reduction, P < 0.03) and iron (17% reduction, P < 0.05).
  
  
  CONCLUSIONS
  Several dietary nutrients appear to protect against oral precancerous lesions that are strongly associated with reverse smoking. The results of this study indicate scope for targeting dietary factors in preventing oral cancer, which should be coupled with aggressive anti-tobacco use efforts.
authors.affiliation: Department of Epidemiology and Biostatistics, University of South Carolina School of Public Health, Columbia 29208, USA. jhebert@sph.sc.edu
authors.forename: James R
authors.initials: JR
authors.lastname: Hebert
authors.forename: Prakash C
authors.initials: PC
authors.lastname: Gupta
authors.forename: Ramesh B
authors.initials: RB
authors.lastname: Bhonsle
authors.forename: Hemali
authors.initials: H
authors.lastname: Mehta
authors.forename: Wei
authors.initials: W
authors.lastname: Zheng
authors.forename: Maureen
authors.initials: M
authors.lastname: Sanderson
authors.forename: Jane
authors.initials: J
authors.lastname: Teas
mesh_terms: D002136:Calcium, Dietary / Q000008:administration & dosage; D016022:Case-Control Studies; D004043:Dietary Fiber / Q000008:administration & dosage; D005247:Feeding Behavior; D005260:Female; D006293:Health Promotion; D006801:Humans; D007194:India / Q000453:epidemiology; D019266:Iron, Dietary / Q000008:administration & dosage; D008297:Male; D008875:Middle Aged; D009062:Mouth Neoplasms / Q000453:epidemiology* / Q000517:prevention & control; D011159:Population Surveillance; D011230:Precancerous Conditions / Q000453:epidemiology*; D012307:Risk Factors; D012424:Rural Population; D012907:Smoking / Q000009:adverse effects*; D016540:Smoking Cessation; D011795:Surveys and Questionnaires; D015032:Zinc / Q000008:administration & dosage
chemical_list: D002136:Calcium, Dietary; D004043:Dietary Fiber; D019266:Iron, Dietary; D015032:Zinc