Am in Miami with my ailing Dad and while seeking diagnostic workup am even more focused on the role that the type of food has for contributing to healthy living. Chalk it up for eating fish (really omega-3 fatty acids) especially important in the elderly and in developing countries. Here is a couple of recent studies that show the benefits of eating fish:-
http://www.mindfood.com/at-more-evidence-that-fish-is-brain-food.seo
http://www.mindfood.com/at-fish-eye-disease-vision-loss-macular-degeneration.seo
