Background: Evidence from animal models and observational studies in humans has suggested that there is an inverse relationship between dietary intake of omega 3 long-chain polyunsaturated fatty acids (LCPUFA) and risk of developing age-related macular degeneration (AMD) or progression to advanced AMD.
Objectives: To review the evidence that increasing the levels of omega 3 LCPUFA in the diet (either by eating more foods rich in omega 3 or by taking nutritional supplements) prevents AMD or slows the progression of AMD.
Search methods: We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (2015, Issue 1), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to February 2015), EMBASE (January 1980 to February 2015), Latin American and Caribbean Health Sciences Literature Database (LILACS) (January 1982 to February 2015), the ISRCTN registry (www.isrctn.com/editAdvancedSearch), ClinicalTrials.gov (www.clinicaltrials.gov) and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 2 February 2015.
Selection criteria: We included randomised controlled trials (RCTs) where increased dietary intake of omega 3 LCPUFA was compared to placebo or no intervention with the aim of preventing the development of AMD, or slowing its progression.
Data collection and analysis: Both authors independently selected studies, assessed them for risk of bias and extracted data. One author entered data into RevMan 5 and the other author checked the data entry. We conducted a meta-analysis for one primary outcome, progression of AMD, using a fixed-effect inverse variance model.
Main results: We included two RCTs in this review, in which 2343 participants with AMD were randomised to receive either omega 3 fatty acid supplements or a placebo. The trials, which had a low risk of bias, were conducted in the USA and France. Overall, there was no evidence that people who took omega 3 fatty acid supplements were at decreased (or increased risk) of progression to advanced AMD (pooled hazard ratio (HR) 0.96, 95% confidence interval (CI) 0.84 to 1.10, high quality evidence). Similarly, people taking these supplements were no more (or less) likely to lose 15 or more letters of visual acuity (USA study HR 0.96, 95% CI 0.84 to 1.10; French study at 36 months risk ratio (RR) 1.25, 95% CI 0.69 to 2.26, participants = 230). The number of adverse events was similar in the intervention and placebo groups (USA study participants with one or more serious adverse event RR 1.00, 95% CI 0.91 to 1.09, participants = 2080; French study total adverse events RR 1.05, 95% CI 0.97 to 1.13, participants = 263).
Authors' conclusions: This review found that omega 3 LCPUFA supplementation in people with AMD for periods up to five years does not reduce the risk of progression to advanced AMD or the development of moderate to severe visual loss. No published randomised trials were identified on dietary omega 3 fatty acids for primary prevention of AMD. Currently available evidence does not support increasing dietary intake of omega 3 LCPUFA for the explicit purpose of preventing or slowing the progression of AMD.