Our eyesight is so precious and something we tend to take for granted.
As we get older, subtle changes start to occur with our eyesight, we discover the need for longer arms to be able to read clearly and magnification for road maps in order to be able to decipher road names.
Cataracts are a well known phenomenon, but what about one of the leading causes of blindness in the elderly, called age-related macular degeneration or AMD?
In AMD central vision is lost in an area called the macula. This occurs as a result to damage to the retina. The effect is such that it makes reading and face recognition difficult. Imagine looking through the lens of a camera and having the centre of the image you are looking at being so blurry so that you can only see the periphery clearly.
It is also common, affecting around 10% of the population aged between 66 to 74 years. The degree of macular degeneration that develops varying from person to person.
So where does eating fish fit in?
Omega-3’s provide us with essential fatty acids, which we need for normal brain cell function and to protect our blood vessels against atheroscleosis. Consuming a diet high in omega-3’s is thought to protect the eye from retinal damage. Studies using mice have shown that consuming more dietary omega-3 resulted in slower progression of the disease and a lowering of associated inflammatory molecules.
In 2007 the University of Melbourne undertook a meta-analysis, evaluating the results from nine studies with over 88,000 participants including 3000+ who had AMD.
The results showed eating a diet with a high intake of omega-3 fatty acids was associated with a 38% reduction of the risk of developing advanced AMD, while eating fish twice a week was associated with a reduced risk for developing either early and late AMD.
Brain cells (and hence neural retinal cells) require long chain fatty acids from omega-3s for their formation. The outer cells of the retina are continually being shed and regenerated so a continuing supply of omega-3 is essential.
A new study from the John Hopkins School of Medicine looked at whether eating fish made a difference in the incidence of AMD in a group of 2391 people aged 65 to 84 years. The participants undertook a questionnaire looking at their fish and shellfish consumption and they were examined for signs of AMD. Of the group 227 people had early AMD, 153 had intermediate stage disease and 68 had advanced AMD. This study reported that eating omega-3 rich fish and shellfish protects against advanced AMD. They found noted that most of the participants including the control group were already eating fish at least once a week, but interestingly those with advanced AMD were significantly less likely to consume high omega 3 fish and seafood.
There are other risk factors for AMD such as smoking and obesity, however the research strongly suggests that consuming omega-3 from fish is eye protective.
Refs:
1. Tuo et al. A High Omega-3 Fatty Acid Diet Reduces Retinal Lesions in a Murine Model of Macular Degeneration. American Journal Of Pathology, 2009; DOI: 10.2353/ajpath.2009.090089
2 Elaine W-T. Chong; Andreas J. Kreis; Tien Y. Wong; Julie A. Simpson; Robyn H. Guymer. Dietary {omega}-3 Fatty Acid and Fish Intake in the Primary Prevention of Age-Related Macular Degeneration: A Systematic Review and Meta-analysis. Arch Ophthalmol., 2008;126(6):826-833 [link]
3 Bonnielin K. Swenor, Susan Bressler, Laura Caulfield, Sheila K. West. The Impact of Fish and Shellfish Consumption on Age-Related Macular Degeneration. Ophthalmology, 2010; DOI: 10.1016/j.ophtha.2010.03.058
