Chalk up another possible health benefit of eating fish: prevention of age-related macular degeneration, the leading cause of irreversible blindness in the US.
The macula is the central portion of the retina in the eye and when it is damaged, visual problems -- including blindness -- are the unfortunate result.
Australian researchers found that more frequent consumption of fish appeared to protect against late age-related macular degeneration. Only a moderate intake of fish was necessary for the protective effect.
Those who ate fish one to three times a month had about half the risk of late-stage disease than those who ate fish less than once a month. And more fish was not necessarily better.
The greatest amount of protection was seen in those who ate one serving of fish a week, and there was no additional benefit of consuming more.
The investigators note that eating too much fish may interfere with the absorption of vitamin E in the elderly, which could explain the threshold protective effect from dietary fish.
Archives of Ophthalmology March, 2000;118:401-404
Identifying preventable risk factors for age-related macular degeneration, now the most common cause of blindness in western countries, may be the only way of reducing the burden of this disease as current treatments are rarely effective in the longer term. It is important to recognize the threshold effect the authors describe.
There did not appear to be any benefit of having fish more than once a week. The authors do not address the additional serious concern that virtually all waterways in the world are contaminated and there really is no such thing as organic commercial fish.
If one is healthy, it is likely that they could effectively eliminate the heavy metals and PCBs that many fish have. So, it appears that fish more than once a week are not necessary. To obtain the benefits of fish one can use a high quality EPA/DHA supplement. Mega doses are not required and it is likely one a day would be sufficient.