title: Association of vitamin A and β-carotene with risk for age-related cataract: a meta-analysis.
abstract: OBJECTIVE
  Whether vitamin A and β-carotene as nutrients are protective factors against cataracts remains unclear. Thus, the aim of this study was to summarize the evidence from epidemiologic studies of vitamin A and β-carotene with the risk for cataract.
  
  
  METHODS
  Pertinent studies were identified by a search of PubMed, Web of Science, Google Scholar, and Wan Fang Med Online. A fixed- or random-effects model was used based on heterogeneity test. Meta-regression and "leave-one-out" analysis were used to explore potential sources of between-study heterogeneity. Publication bias was estimated using Egger's regression asymmetry test.
  
  
  RESULTS
  Twenty-two articles were included in this meta-analysis. The relative risk (RR; 95% confidence interval [CI]) for cataract for the highest versus lowest category of serum β-carotene levels was 0.827 (95% CI, 0.736-0.930), and the association was significant between β-carotene intake and cataract risk (RR, 0.937; 95% CI, 0.880-0.997). Significant association of cataract risk with vitamin A intake was found overall (RR, 0.831; 95% CI, 0.757-0.913). However, no significant association was found between serum vitamin A and cataract risk (RR, 0.925; 95% CI, 0.675-1.266; I(2) = 63.1%), but an inverse association was observed with risk for cataract with serum vitamin A after sensitivity analysis (RR, 0.765; 95% CI, 0.654-0.894; I(2) = 29.1%).
  
  
  CONCLUSIONS
  Greater vitamin A and β-carotene intakes might be inversely associated with risk for cataract.
authors.affiliation: School of Nursing, the Medical College of Qingdao University, Qingdao, People's Republic of China. Electronic address: wangaiminqy@126.com.
authors.forename: Aimin
authors.initials: A
authors.lastname: Wang
authors.affiliation: School of Nursing, the Medical College of Qingdao University, Qingdao, People's Republic of China.
authors.forename: Jing
authors.initials: J
authors.lastname: Han
authors.affiliation: School of Nursing, the Medical College of Qingdao University, Qingdao, People's Republic of China.
authors.forename: Yunxia
authors.initials: Y
authors.lastname: Jiang
authors.affiliation: Department of Epidemiology and Health Statistics, the Medical College of Qingdao University, Qingdao, People's Republic of China.
authors.forename: Dongfeng
authors.initials: D
authors.lastname: Zhang
mesh_terms: D000975:Antioxidants / Q000008:administration & dosage; D002386:Cataract / Q000209:etiology / Q000517:prevention & control; D004032:Diet; D019587:Dietary Supplements; D006801:Humans; D012306:Risk; D014801:Vitamin A / Q000008:administration & dosage / Q000097:blood; D014815:Vitamins / Q000008:administration & dosage / Q000097:blood; D019207:beta Carotene / Q000008:administration & dosage / Q000097:blood
chemical_list: D000975:Antioxidants; D014815:Vitamins; D019207:beta Carotene; D014801:Vitamin A
keywords: Cataract; Meta-analysis; Vitamin A; β-carotene