High Omega-3 Diet Continues to Show Benefits for Eye Health

by | Sep 15, 2009 | 2009, Eye Health, Omega - 3

Written by Greg Arnold, DC, CSCS. A study in mice has shown that omega-3 fats can help eye health even when genetically at risk for age-related macular degeneration.

Age-related macular degeneration is the leading cause of irreversible visual impairment and blindness in the U.S. and other developed countries throughout the world (1), causing vision loss in more than 200,000 people every year (2). This is expected to increase to 3 million in the U.S. alone over the next 20 years (3).  Unfortunately, the cause of age-related macular degeneration still remains a mystery, with cigarette smoking and advancing age as the only two known risk factors (4).

When looking at ways to help maintain eye health, omega-3 fatty acids have consistently been found to play a very important role for a number of reasons.  First, DHA, an omega-3 fat found in fish oil, makes up nearly half the fat content of the light receptors in the eye (5).  Second, DHA helps preserve “vital retinal functions” in the eye (6).

Now a new study in mice (7) has shown that omega-3 fats can help eye health even when genetically at risk for AMD.  In the study, researchers used mice with a genetic makeup that causes spontaneous lesions to the eye and produced AMD symptoms.  There were seven mice in each of two groups, and the researchers fed them either a high omega-3 diet (10% fat by weight and a mixture of fish oil, olive oil, and safflower oil that produced a 3:1 omega-6/omega-3 ratio) or a high omega-6 diet (same oils that produced a 19:1 omega-6/omega-3 ratio) for 9 months.  The researchers obtained samples of eye cells before and after the study, and also performed eye examinations on the mice every 3 months.

The researches started to notice differences between the two groups by the 4th month of the study.  Specifically, 57% of mice in the high omega-3 group had improved eye health (defined as “lesion regression” with decreased number and size of eye lesions) compared to only 4% in the low omega-3 group.  This eventually improved to 90% of mice in the high omega-3 group by the 7th month, compared to only 16% of mice in the low omega-3 group.

When it came to worsening eye heath (defined as “lesion progression” with increased number and size of eye lesions), 7% of high omega-3 mice had lesion progression, compared to 30% in the low omega-3 group.  This improved to 0% of the high omega-3 group, compared to 42% of the low omega-3 group by the end of the 7th month.  The researchers concluded that “This murine* model provides a useful tool to evaluate therapies that might delay the development of Age-Related Macular Degeneration.”.  Although this is a small study and needs confirmation in human studies, the percent improvement is worthy of note.

Source: Tuo, Jingsheng, et al. “A high omega-3 fatty acid diet reduces retinal lesions in a murine model of macular degeneration.” The American journal of pathology 175.2 (2009): 799-807.

© 2009 American Society for Investigative Pathology

Posted September 15, 2009.

* rat and mouse research

References:

  1. National Advisory Eye Council. Vision Research—A National Plan: 1999-2003, Vol. 1. A Report of the National Advisory Eye Council. Bethesda, Md: National Institutes of Health; 1999. NIH publication 98-4120.
  2. National Institutes of Health National Eye Institute and Prevent Blindness America. Vision Problems in the US: Prevalence of Adult Vision Impairment and Age-Related Eye Disease in America. Schaumburg, Ill: Prevent Blindness America; 2002.
  3. Eye Disease Prevalence Research Group. Prevalence of age-related macular degeneration in the United States. Arch Ophthalmol. 2004;122:564-572.
  4. Mitchell P, Wang JJ, Smith W, Leeder S. Smoking and the 5-year incidence of age-related maculopathy. Arch Ophthalmol. 2002;120:1357-1363.
  5. Rotstein NP, Politi LE, German OL, Girotti R: Protective effect of docosahexaenoic acid on oxidative stress-induced apoptosis of retina photoreceptors. Invest Ophthalmol Vis Sci 2003, 44:2252–2259.
  6. Birch EE, Birch DG, Hoffman DR, Uauy R: Dietary essential fatty acid supply and visual acuity development. Invest Ophthalmol Vis Sci 1992, 33:3242–3253.
  7. Tuo J.  A High Omega-3 Fatty Acid Diet Reduces Retinal Lesions in a Murine Model of Macular Degeneration.  The American Journal of Pathology 2009; 175(2): 799-807.