Long-term Intakes of EPA and DHA Associated with Reduced Occurrence of Age-Related Macular Degeneration
Wu, J. et al., Am. Academy of Ophthalmology, in press, 2017
Dept. of Nutrition, Harvard T. H. Chan School of Public Health, Boston, Mass., USA
Age-related macular degeneration (ARMD) involves the progressive deterioration of a key region of the retina called the macula. Early in the disorder, vision is typically distorted or hazy which often leads to irreversible loss of central vision. ARMD accounts for approx. 12 % of blindness in North America with close to 30 % of the population over the age of 74 being afflicted with the disease. The present study was aimed to determine the relation of EPA/DHA omega-3 fatty acid intakes in the aging population to the subsequent occurrence of ARMD with a very long-term follow-up (spanning 28 years).
The researchers followed 75,889 women from the Nurses’ Health Study and 38,961men from the Health Professionals Follow-Up Study who were at least 50 years old. At the beginning, and every four years thereafter, dietary/nutrient intakes were assessed by the use of food frequency questionnaires (including various types of fish/seafood) and nutrient contents based on the US Dept. of Agriculture Database (including omega-3 fatty acids). The subsequent occurrence and diagnosis of ARMD was confirmed by the participants’ eye doctor. Pooling the findings from both population groups indicated that those in the highest quintile (top 20 %) with respect to DHA intakes (median intakes in the two study groups of 279 and 390 mgs/day) had a significant 22% lower occurrence of intermediate ARMD when compared to those in the lowest quintile (median intakes of 52 and 70 mgs/day). Those in the highest quintile (excluding the minority who also used supplements) with respect to EPA plus DHA intakes (median intakes of 355 and 564 mgs/day) experienced an overall 14 % lower rate of intermediate ARMD as compared to those in the lowest quintile (66 and 90 mgs/day). By including the supplement users, the highest quintile (median EPA plus DHA intakes of 390 and 625 mgs/day) showed a 17 % lower risk relative to those in the lowest quintile (70 and 94 mgs/day). With respect to total fatty fish intakes, those consuming five or more servings/week exhibited a 39 % lower risk of developing intermediate ARDM as compared to those who rarely consumed such. The authors concluded that ‘higher intakes of EPA and DHA may prevent or delay the occurrence of visually-significant intermediate age-related macular degeneration’.
Dr. Holub's Comments:
Since less than 5 % of all the participants from both groups (pooled) were using fish oil supplements containing EPA/DHA, most of the long-chain omega-3 fatty acids as consumed would be coming from fish/seafood sources. The authors suggest that EPA plus DHA intakes equal to or greater than 350 mgs/day or two or more servings of fatty fish/week may provide a moderate reduction in the risk of ARMD. Such a level of intake is more than double that of the average adult intake in North America. It is noted that the AREDS2 trial did not find a significant reduction in the risk for developing advanced ARDM in patients at high risk for such who were given 1 gm (1000 mgs) of supplemental EPA plus DHA per day over a period of five years (J. Am. Medical Assoc., 309: 2005-2015 (2013)). However, it has been reported from a pilot study that much higher doses of EPA/DHA (3400 mgs EPA plus 1600 mgs DHA – total of 5000 mgs daily)) resulted in a significant improvement in visual acuity as determined by the improvement of lines of vision that could be read on a chart by elderly patients with ‘dry’ ARDM. Further clinical trials using higher intakes of EPA/DHA for the potential prevention or complementary management of ARDM are warranted.