title: Toxic risks and nutritional benefits of traditional diet on near visual contrast sensitivity and color vision in the Brazilian Amazon.
abstract: BACKGROUND
  Visual functions are known to be sensitive to toxins such as mercury (Hg) and lead (Pb), while omega-3 fatty acids (FA) and selenium (Se) may be protective. In the Tapajós region of the Brazilian Amazon, all of these elements are present in the local diet.
  
  
  OBJECTIVE
  Examine how near visual contrast sensitivity and acquired color vision loss vary with biomarkers of toxic exposures (Hg and Pb) and the nutrients Se and omega-3 FA in riverside communities of the Tapajós.
  
  
  METHODS
  Complete visuo-ocular examinations were performed. Near visual contrast sensitivity and color vision were assessed in 228 participants (≥15 years) without diagnosed age-related cataracts or ocular pathologies and with near visual acuity refracted to at least 20/40. Biomarkers of Hg (hair), Pb (blood), Se (plasma), and the omega-3 FAs eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in plasma phospholipids were measured. Multiple linear regressions were used to examine the relations between visual outcomes and biomarkers, taking into account age, sex, drinking and smoking.
  
  
  RESULTS
  Reduced contrast sensitivity at all spatial frequencies was associated with hair Hg, while %EPA, and to a lesser extent %EPA+DHA, were associated with better visual function. The intermediate spatial frequency of contrast sensitivity (12 cycles/degree) was negatively related to blood Pb and positively associated with plasma Se. Acquired color vision loss increased with hair Hg and decreased with plasma Se and %EPA.
  
  
  CONCLUSIONS
  These findings suggest that the local diet of riverside communities of the Amazon contain toxic substances that can have deleterious effects on vision as well as nutrients that are beneficial for visual function. Since remediation at the source is a long process, a better knowledge of the nutrient content and health effects of traditional foods would be useful to minimize harmful effects of Hg and Pb exposure.
authors.affiliation: Centre de recherche interdisciplinaire sur la biologie, la santé, la société et l'environnement (CINBIOSE), Université du Québec à Montréal, Montréal, Canada. fillion.myriam@uqam.ca
authors.forename: Myriam
authors.initials: M
authors.lastname: Fillion
authors.forename: Mélanie
authors.initials: M
authors.lastname: Lemire
authors.forename: Aline
authors.initials: A
authors.lastname: Philibert
authors.forename: Benoît
authors.initials: B
authors.lastname: Frenette
authors.forename: Hope Alberta
authors.initials: HA
authors.lastname: Weiler
authors.forename: Jason Robert
authors.initials: JR
authors.lastname: Deguire
authors.forename: Jean Remy Davée
authors.initials: JR
authors.lastname: Guimarães
authors.forename: Fabrice
authors.initials: F
authors.lastname: Larribe
authors.forename: Fernando
authors.initials: F
authors.lastname: Barbosa
authors.forename: Donna
authors.initials: D
authors.lastname: Mergler
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D001938:Brazil; D055253:Color Vision; D003117:Color Vision Defects / Q000209:etiology / Q000517:prevention & control; D015350:Contrast Sensitivity; D003430:Cross-Sectional Studies; D004032:Diet / Q000009:adverse effects; D015525:Fatty Acids, Omega-3 / Q000097:blood; D005260:Female; D005506:Food Contamination; D006197:Hair / Q000737:chemistry; D006801:Humans; D007854:Lead / Q000009:adverse effects / Q000097:blood; D016014:Linear Models; D008297:Male; D017669:Mercury Compounds / Q000009:adverse effects / Q000032:analysis; D008875:Middle Aged; D015999:Multivariate Analysis; D012307:Risk Factors; D017747:Seafood / Q000009:adverse effects / Q000032:analysis; D012643:Selenium / Q000097:blood; D014787:Vision Tests; D055815:Young Adult
chemical_list: D015415:Biomarkers; D015525:Fatty Acids, Omega-3; D017669:Mercury Compounds; D007854:Lead; D012643:Selenium