Eye Benefits of Omega-3 Fatty Acids
You may find it hard to believe that fat is essential to your health, but it's true. Without fat, our bodies can't function properly. And without the proper kinds of fats in our diet, our eye health also may suffer.
Fatty acids are the "building blocks" of fat. These important nutrients are critical for the normal production and functioning of cells, muscles, nerves and organs. Fatty acids also are required for the production of hormone-like compounds that help regulate blood pressure, heart rate and blood clotting.
Some fatty acids called essential fatty acids (EFAs) are necessary to our diet, because our body can't produce them. To stay healthy, we must obtain these fatty acids from our food.
Two types of EFAs are omega-3 fatty acids and omega-6 fatty acids. Studies have found that omega-3 fatty acids, in particular, may benefit eye health.
Omega-3 fatty acids include docosahexaenoic acid (DHA), eicoapentaenoic acid (EPA) and alpha-linolenic acid (ALA).
Omega-3 Fatty Acids and Infant Vision Development
A number of clinical studies have shown omega-3 fatty acids are essential for normal infant vision development.
Grilled salmon is an excellent natural source of omega-3 fatty acids.
DHA and other omega-3 fatty acids are found in maternal breast milk and also are added to some supplemented infant formulas. Omega-3 supplemental formulas appear to stimulate vision development in infants.
According to an analysis of several studies conducted by researchers at Harvard School of Public Health and published in the journal Pediatrics, the authors found that healthy pre-term infants who were fed DHA-supplemented formula showed significantly better visual acuity at 2 and 4 months of age, compared with similar pre-term infants who were fed formula that did not contain the omega-3 supplement.
Adequate amounts of DHA and other omega-3 fatty acids in the diet of pregnant women also appear to be important in normal infant vision development.
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In a study published in the American Journal of Clinical Nutrition, Canadian researchers found that infant girls whose mothers received DHA supplements from their fourth month of pregnancy until delivery were less likely to have below-average visual acuity at 2 months of age than infant girls whose mothers did not receive the omega-3 supplements.
Adult Eye Benefits of Omega-3 Fatty Acids
Several studies suggest omega-3 fatty acids may help protect adult eyes from macular degeneration and dry eye syndrome. Essential fatty acids also may help proper drainage of intraocular fluid from the eye, decreasing the risk of high eye pressure and glaucoma.
In a large European study published in 2008, participants who ate oily fish (an excellent source of DHA and EPA omega-3 fatty acids) at least once per week had half the risk of developing neovascular ("wet") macular degeneration, compared with those who ate fish less than once per week.
Also, a 2009 National Eye Institute (NEI) study that used data obtained from the Age-Related Eye Disease Study (AREDS) found participants who reported the highest level of omega-3 fatty acids in their diet were 30 percent less likely than their peers to develop macular degeneration during a 12-year period.
In May 2013, the NEI published results of a large follow-up to the original AREDS study called AREDS2. Among other things, AREDS2 investigated whether daily supplementation of omega-3 fatty acids, along with the original AREDS nutritional supplement or modifications of that formula which contained beta-carotene, vitamin C, vitamin E, zinc and copper would further reduce the risk of AMD progression among study participants with early signs of macular degeneration. (The original AREDS supplement reduced the risk of AMD progression by 25 percent among a similar population.)
A somewhat surprising result of AREDS2 was that participants who supplemented their diet with 1,000 mg of omega-3s daily (350 mg DHA and 650 mg EPA) did not show any reduction of their risk for progressive AMD over the 5-year duration of the study, compared with participants who did not receive omega-3 supplements.
Possible explanations for these different findings from AREDS and AREDS2 data may be that omega-3 fatty acids are more effective at reducing the risk of age-related eye diseases when obtained via food sources rather than from nutritional supplements, and that a healthy diet containing plenty of omega-3s along with other important nutrients consumed over a person's lifetime is more protective than taking nutritional supplements for a 5-year period.
Omega-3 fatty acids also have been found to reduce the risk of dry eyes. In a study of more than 32,000 women between the ages of 45 and 84, those with the highest ratio of (potentially harmful) omega-6 fatty acids to beneficial omega-3 fatty acids in their diet (15-to-1) had a significantly greater risk of dry eye syndrome, compared with the women with the lowest ratio (less than 4-to-1). The study also found that the women who ate at least two servings of tuna per week had significantly less risk of dry eye than women who ate one or fewer servings per week.
Omega-3 fatty acids also may help treat dry eyes. In a recent study of dry eyes induced in mice, topical application of the omega-3 fatty acid ALA led to a significant decrease in dry eye signs and inflammation associated with dry eye.
While both omega-3 and omega-6 fatty acids are important to health, the balance of these two types of EFAs in our diet is extremely important. Most experts believe the ratio of omega-6 to omega-3 fatty acids in a healthy diet should be 4-to-1 or lower.
Unfortunately, the typical American diet, characterized by significant amounts of meat and processed foods, tends to contain 10 to 30 times more omega-6 than omega-3 fatty acids. This imbalance of omega-6 ("bad") fatty acids to omega-3 ("good") fatty acids appears to be a contributing cause of a number of serious health problems, including heart disease, cancer, asthma, arthritis and depression.
One of the best steps you can take to improve your diet is to eat more foods that are rich in omega-3 fatty acids and fewer that are high in omega-6 fatty acids.
The best food sources of beneficial omega-3 fatty acids are cold-water fish, which are high in both DHA and EPA. Examples include sardines, herring, salmon and tuna. Wild-caught varieties usually are better than "farmed" fish, which typically are subject to higher levels of pollutants and chemicals.
The American Heart Association recommends a minimum of two servings of cold-water fish weekly to reduce the risk of cardiovascular disease, and many eye doctors likewise recommend a diet high in omega-3 fatty acids to reduce the risk of eye problems.
If you aren't a fish lover, another way to make sure your diet contains enough omega-3s it to take fish oil supplements. These are available in capsule and liquid form, and many varieties feature a "non-fishy" taste.
Other good sources of omega-3 fatty acids include flaxseeds, flaxseed oil, walnuts and dark green leafy vegetables. However, your body cannot process the ALA omega-3 fatty acids from these vegetarian sources as easily as the DHA and EPA omega-3 fatty acids found in fish.
To reduce your intake of omega-6s, avoid fried and highly processed foods. Many cooking oils, including sunflower oil and corn oil, are very high in omega-6 fatty acids. High cooking temperatures also create harmful trans-fatty acids, or "trans-fats."
Trans fats interfere with the body's absorption of beneficial omega-3 fatty acids and may contribute to a number of serious diseases, including cancer, heart disease, atherosclerosis (hardening of the arteries), high blood pressure, diabetes, obesity, arthritis and immune system disorders.
Currently, there is no Recommended Dietary Allowance (RDA) for omega-3 fatty acids. But, according to the American Heart Association, research suggests daily intakes of DHA and EPA (combined) ranging from 500 milligrams (0.5 gram) to 1.8 grams (either from fish or fish oil supplements) significantly reduces cardiac risks. For ALA, daily intakes of 1.5 to 3 grams (g) seem to be beneficial.
|Food||DHA and EPA Omega-3s (total), grams|
|Salmon, Atlantic (half fillet, grilled)||3.89|
|Mackerel, Pacific (1 fillet, grilled)||3.25|
|Sardine oil (1 tablespoon)||2.83|
|Salmon, Chinook (half fillet, grilled)||2.68|
|Cod liver oil (1 tablespoon)||2.43|
|Salmon, pink (half fillet, grilled)||1.60|
|Herring oil (1 tablespoon)||1.43|
|Sardines, canned in oil (approx. 3 ounces)||0.90|
|White tuna, canned in water (approx. 3 ounces)||0.73|
|Source: National Agriculture Library, U.S. Dept. of Agriculture|
For a more nutritious diet and potentially better eye health, try these simple changes:
- Replace cooking oils that are high in omega-6 fatty acids with olive oil, which has significantly lower levels of omega-6 fatty acids.
- Eat plenty of fish, fruits and vegetables.
- Avoid hydrogenated oils (found in many snack foods) and margarine.
- Avoid fried foods and foods containing trans fats.
- Limit your consumption of red meat.
Choosing a healthy diet that includes a variety of foods with plenty of omega-3 fatty acids and limiting your intake of potentially harmful omega-6 fatty acids will significantly increase your odds of a lifetime of good vision and vibrant health.
Oily fish consumption, dietary docosahexaenoic acid and eicosapentaenoic acid intakes, and associations with neovascular age-related macular degeneration. American Journal of Clinical Nutrition. August 2008.
Essential n-3 fatty acids in pregnant women and early visual acuity maturation in term infants. American Journal of Clinical Nutrition. March 2008.
Topical omega-3 and omega-6 fatty acids for treatment of dry eye. Archives of Ophthalmology. February 2008.
Relation between dietary omega-3 and omega-6 fatty acids and clinically diagnosed dry eye syndrome in women. American Journal of Clinical Nutrition. October 2005.
Fish consumption, fish oil, omega-3 fatty acids, and cardiovascular disease. American Heart Association Scientific Statement. Circulation. 2002.
Meta-analysis of dietary essential fatty acids and long-chain polyunsaturated fatty acids as they relate to visual resolution acuity in healthy preterm infants. Pediatrics. June 2000.
Dietary fat and fish intake and age-related maculopathy. Archives of Ophthalmology. March 2000.
NIH study provides clarity on supplements for protection against blinding eye disease. National Eye Institute. Press release issued May 2013.
About the Author: Gary Heiting, OD, is senior editor of AllAboutVision.com. Dr. Heiting has more than 25 years of experience as an eye care provider, health educator and consultant to the eyewear industry. His special interests include contact lenses, nutrition and preventive vision care. Connect with Dr. Heiting via Google+.
[Page updated February 2015]