14 March 2011
Dietary Omega-3 Fatty Acid and Fish Intake and Incident Age-Related Macular Degeneration in Women
Christen , W. G. et al., Arch. Ophthamol., in press , 2011
Div. of Preventive Medicine and Aging , Dept. of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA, USA
Age-related macular degeneration (AMD) is a common disorder which can lead to severe vision loss in its advanced stages.The objective of the present study was to determine if higher intakes of omega-3 fatty acids and fish could influence the occurrence of AMD over an extended time period in a large population of women on follow-up. For this purpose, 39,876 women (average age of 55 years) free of AMD at onset were assessed for their food/fish intakes via a food-frequency questionnaire along with estimation of their individual fatty acid intakes from nutrient compositions of the foods consumed. During an average follow-up period of 10 years, the development of AMD responsible for a reduction in visual acuity was determined.
Women in the highest tertile (top 33 %) with respect to DHA intakes (median intake of 230 mg /day) exhibited a 38 % lower risk for developing visually-significant AMD relative to those in the lowest tertile (median DHA intake of only 60 mg/day) when adjusting for numerous other factors (age, blood pressure, cholesterol, diabetes, smoking , others). Those in the highest tertile for EPA intakes and (DHA plus EPA ) intakes exhibited lowered risks of 34 % and 37 %, respectively, as compared to those in the lowest tertile. No significant reductions in risk were seen for higher intakes of alpha-linolenic omega-3 (ALA) or omega-6 polyunsaturated fatty acids. Total fish intakes of one or more servings per week were associated with a 42 % lower risk as compared to those women who rarely ate fish (less than one serving/month). The authors indicate that higher intakes of DHA/EPA and fish may be of significant benefit in the primary prevention of AMD.
Dr. Holub’s Comments :
A reduced formation of pro-inflammatory eicosanoids from arachidonic acid (omega-6) upon the ingestion of DHA/EPA and the production of anti-inflammatory bioactive molecules known as resolvins and protectins from DHA/EPA are suggested to contribute to the reduced AMD with higher intakes of fish containing these long-chain omega-3 fatty acids. The intake of the short-chain omega-3 fatty acid as ALA (mainly from plant-based food sources ) , which is ingested at approx. 10-times the level of DHA, did not show a preventive effect on AMD in this study. This likely reflects the very limited conversion of ALA to DHA/EPA in the human body (average of 3.5 % conversion efficiency from ALA to DHA in adults of mixed genders).