RE: salmon
Dr NV Perricone, who's written several books on skin care and anti-aging, is a big advocate of salmon because it's loaded with omega 3 essential fatty acids. Omega 3's have anti-imflammatory properties, which is why it's good for so many ailments. Dr Perricone believes the biggest factor in aging, be it the skin or the body, is inflammation.
A lot of what he says in his books are the same things we recommend here - eat several small meals a day, always include a protein source in each meal, avoid high glycemic carbs, eat enough "healthy fats", drink a lot of water, take vitamins and anti-oxidants, and (surprise!) weight train.