title: Self-reported Calcium Supplementation and Age-Related Macular Degeneration.
abstract: OBJECTIVE
  Despite widespread use of calcium supplementation among elderly people, little is known about the association between such consumption and the prevalence of age-related macular degeneration (AMD) in the United States.
  
  
  OBJECTIVE
  To investigate the association between self-reported supplementary calcium consumption and the prevalence of AMD in a representative US sample.
  
  
  METHODS
  This cross-sectional study included 3191 participants 40 years and older in the 2007-2008 National Health and Nutrition Examination Survey (NHANES) who were evaluated for the presence or absence of AMD by fundus photography. Participants were interviewed regarding use of dietary supplements and antacids during the 30-day period preceding enrollment. Self-reported supplementary intake of calcium was aggregated and divided into quintiles. Fundus photographs were graded for the presence or absence of AMD. Information regarding demographics, comorbidities, and health-related behaviors was obtained via interview. Multivariable logistic regression models were created to determine the odds of an AMD diagnosis among participants in each quintile of self-reported calcium vs participants not self-reporting supplementary calcium consumption after adjusting for confounders.
  
  
  METHODS
  Self-reported use of calcium supplements.
  
  
  METHODS
  Presence or absence of AMD by fundus photography.
  
  
  RESULTS
  A total of 248 participants (7.8%) were diagnosed with AMD. Mean ages were 67.2 years for those with AMD and 55.8 for those without AMD. After adjustment for potential confounding variables, study participants who self-reported consumption of more than 800 mg/d of supplementary calcium were found to have higher odds of an AMD diagnosis based on fundus photography evaluation compared with those not self-reporting supplementary calcium consumption (odds ratio, 1.85; 95% CI, 1.25-2.75). The association between self-reported supplementary calcium intake and AMD was stronger in older than younger individuals (odds ratio, 2.63; 95% CI, 1.52-4.54). A clear dose-response association between the quintiles of self-reported supplementary calcium intake and AMD was not established.
  
  
  CONCLUSIONS
  Self-reported supplementary calcium consumption is associated with increased prevalence of AMD, with the findings suggesting a threshold rather than a dose-response relationship. The stronger association in older individuals may be due to relatively longer duration of calcium supplementation in older individuals.
authors: Department of Ophthalmology, University of California, San Francisco.
authors: Caitlin L M
authors: CL
authors: Kakigi
authors: Department of Ophthalmology, Stanford University, Stanford, California.
authors: Kuldev
authors: K
authors: Singh
authors: Department of Ophthalmology, University of Michigan, Ann Arbor.
authors: Sophia Y
authors: SY
authors: Wang
authors: Department of Epidemiology and Biostatistics, University of California, San Francisco.
authors: Wayne T
authors: WT
authors: Enanoria
authors: Department of Ophthalmology, University of California, San Francisco.
authors: Shan C
authors: SC
authors: Lin
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D000375:Aging / Q000502:physiology; D002136:Calcium, Dietary / Q000008:administration & dosage / Q000009:adverse effects*; D003430:Cross-Sectional Studies; D019587:Dietary Supplements / Q000009:adverse effects*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D016015:Logistic Models; D008268:Macular Degeneration / Q000139:chemically induced* / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009749:Nutrition Surveys; D016017:Odds Ratio; D015995:Prevalence; D018570:Risk Assessment; D057566:Self Report; D012720:Severity of Illness Index; D017678:Sex Distribution; D014481:United States / Q000453:epidemiology
chemical_list: D002136:Calcium, Dietary