Better Vision with Omega-3 and Vitamin D
Two recent studies in the Archives of Ophthalmology suggest that individuals with greater consumption of omega-3 fatty acids and higher vitamin D levels may be at lower risk for developing age-related macular degeneration (AMD), the most common cause of blindness for people over age 50.
There are two primary forms of AMD, the dry form, which is caused by loss of cells in the epithelial layer in the retina, and the wet (or neovascular) form, which is caused by abnormal blood vessel growth in the retina.
Omega-3
In the first study, researchers divided participants into five groups (quintiles) based on total omega-3 fat intake and found that the individuals in the top quintile were 39% less likely to develop wet AMD than people in the lowest quintile of intake. Scientists also looked at a specific omega-3 fatty acid (DHA - docosahexanoic acid), which is found in high concentration in the retina, and observed a 46% reduction in AMD risk when comparing the highest and lowest quintile of intake.
Additionally, fish intake positively correlated with reduced wet AMD risk in the study, but as discussed earlier, I would be reluctant to eat high levels of fish given the potential risk for toxin exposure. Vision disturbances are common in mercury poisoning cases. Contaminant-tested fish oil supplements are much preferred as a safer omega-3 source.
Interestingly, researchers found that high consumption of arachidonic acid (AA) was associated with a 54% increase in wet AMD risk. AA is an omega-6 fatty acid found in high quantities in red meat, dairy, and egg yolks, as well as metabolized from vegetable oils, such as corn and soybean oils commonly used in processed, packaged, and restaurant-prepared foods. This finding once again suggests that it is important to not only ensure adequate omega-3 intake, but also to moderate omega-6 intake, in order to manage inflammation. I addressed this topic in an earlier post.
Why and how is fat intake influencing AMD risk? The researchers involved hypothesize that the fats may be influencing blood vessel and/or nerve function in the eye. As mentioned above, omega-3 fats are found in high concentration in the membranes of cells in the eye, especially in the retina. The balance of fat intake may help to regulate gene expression in these tissues, as well as control inflammation and energy use.
You can a more detailed summary of these potential beneficial effects in this review paper abstract:
The role of omega-3 long-chain polyunsaturated fatty acids in health and disease of the retina
Vitamin D
In the second study, researchers also divided participants into quintiles and found that individuals in the highest quintile of intake had a 36% reduced likelihood of developing early AMD relative to individuals in the lowest quintile.
Why and how may vitamin D be affecting AMD risk? The researchers hypothesize that the benefit may be related to an anti-inflammatory effect and/or the ability to regulate blood vessel growth in the retina.
The scientists looked at dietary and supplemental sources of vitamin D, and noticed that the following were associated with reduced AMD risk:
- Higher milk intake - 25% decreased risk (early AMD)
- Higher fish intake - 59% decreased risk (late AMD)
- Vitamin D supplement intake - 33% decreased risk (early AMD; only in people not drinking milk)
As discussed earlier, moderate sunshine exposure on the skin is the most effective way to ensure optimal vitamin D levels. Milk has low amounts of vitamin D (~100 IU per 8 oz.). Small fish bones contain vitamin D, but the inverse association with AMD risk seen in this study from fish consumption may also be from the omega-3 fats in the fish, as suggested in the first study above. For many, especially the elderly, people who live in northern latitudes, and/or office workers who get little sun, supplements may be the best bet for getting enough vitamin D.
Bottom Line
Ensuring adequate Omega-3 fat intake, moderating omega-6 fat intake, and maintaining optimal vitamin D intake year-round, may all help to reduce your risk of developing AMD. The best time to take action is well before you develop symptoms, as AMD takes years to develop and progress. If you’d like help putting together a program to maintain healthy vision, you can learn more here.
Related Posts
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High Omega-6 to Omega-3 Fat Intake Tied to Inflammation and Depression
Direct Link Between Cancer Prevention and Vitamin D Levels
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