June 27, 2011
By Jessica Forbes MS, CCN
While all beneficial oils are important to health, if there’s one that is a superstar for eye health it would have to be DHA (docosahexaenoic acid). Here are more facts about this amazing fat!
- Foods that are richest in DHA include fatty fish such as wild salmon or herring, sardines, and cod liver oil. A good vegetarian source is algae that has been grown under clean conditions in a lab.
- The body can synthesize DHA from ALA—the omega-3 fat found in flaxseed—but this requires several biochemical steps, each of which requires nutrients. Conversion may be impaired in people deficient in certain nutrients (particularly B vitamins and zinc).
- Very high levels of DHA are found in the retina—in fact, in a higher proportion than is found in any other tissue in the body.
- If dietary intake of DHA is low, the retina will actually conserve and recycle DHA.
- DHA has been indicated as a protective factor in eye strain associated with computer use.
- DHA has been found to slow the progression of vision loss from age-related macular degeneration.
- DHA has the ability to reverse the symptoms of dry eye syndrome.
- The last trimester of pregnancy is a critical time for the accumulation of DHA in the brain and eyes. DHA continues to be important in the months following birth all the way through adolescence, since the brain and eyes continue to mature.
The Adequate Intake for Omega-3 fats including DHA as set by the U.S. Institute of Medicine is 4.5 g/day in infancy, 7-10 g/day for children (ranges given depend on age and gender), 12-16 g/day for adolescents, 12-17 g/day for adults, and 13 g/day for pregnant and lactating women. To see the specific breakdown by age and gender, go to the Linus Pauling Institute’s entry on Omega-3 fats. To put the Adequate Intake into perspective, a pregnant woman could obtain her daily need for Omega-3 fat by eating 8 ounces wild salmon, 2 tablespoons freshly ground whole flaxseed, and 1 tablespoon cod liver oil.