| CI | Confidence interval |
| FFQ | Food frequency questionnaire |
| HR | Hazard risk |
| NOS | Newcastle-Ottawa Scale |
| OR | Odds ratio |
| PSRMA | Preferred Reporting Items for Systematic Reviews and Meta-Analyses |
| RR | Relative risk |
| VA | Vitamin A |
| CI | Confidence interval |
| FFQ | Food frequency questionnaire |
| HR | Hazard risk |
| NOS | Newcastle-Ottawa Scale |
| OR | Odds ratio |
| PSRMA | Preferred Reporting Items for Systematic Reviews and Meta-Analyses |
| RR | Relative risk |
| VA | Vitamin A |