I came across this article online and thought it was definitely worth a read: http://www.dailymail.co.uk/news/article-2546512/How-pet-food-killing-dog-feeding-parsnips-yoghurt.html
The basic premise of the article is stated more strongly than my title-the premise being pet food is killing your dog. I have read a lot about different pet diets over the years including raw diets, various types of pet food, etc. Maverick had pet foot allergies when he was a puppy that made his hair fall out so we had to give him a special type of wet food. As we researched dog foods more we learned that a lot of the mass market brands were stuffed with carbs and had very little protein.
After reading this article, I started googling around seeing what advances have been made in dog food over the past couple of years and the good news is that new niche/high-end food brands are coming out and taking share from the low-end dog foods out there. Just as humans are learning to eat less processed foods and more organic diets, I think it makes intuitive sense that this is likely also the best solution for dogs as well.
I don’t have enough information yet to know if this extends your dog’s life by 1% or 30% on average but I am going to hunt around for studies and see what I can find.