I beleive in the saying, "You are what you eat". A good food documentary to watch if you have a chance on Netflix is "Food Inc". It explains the whole meat business made for mass consumption and using horomones to speed growth. Studies show this to cause cancer and abnormalities in the animals. There's studies showing GMO's, chemicals, pestisides, and fertilizers in fruits and vegestables may do the same.
After doing a lot of studying and research on the subject my wife and I switched our family to an organic diet. It cost a little more and fresh foods may spoil quicker but we notice a difference and taste and quality of our food.
At this time I'm experimenting with organic dog feed and this is what I'm using.

http://www.balancediet.com/

I'm getting great results so far. Solved the problem of one of my dogs with mushy cow poops. Nothing helped. Antibiotics, Raw Feed diet, switching dry feeds, till I made the switch to this stuff. It's fermented so it really helps with digestion. Would like to see what long term results I get on it.