The cases for and against dietary protein for healthy aging

To date, there is very little strong evidence on nutrition and aging, with perhaps the exception of protein consumption. Yet despite the many studies investigating the relationship between protein intake and aging, debate nevertheless continues to rage over whether dietary protein has a net positive or negative effect when it comes to human longevity. As many reading this will be aware, I am in favor of increasing protein intake well above the recommended dietary allowance, but advocates of low-protein diets cite concerning effects on the mammalian target of rapamycin (mTOR) and IGF-1. So what should we make of these data? And why do I still maintain that protein intake is an important part of nutrition for healthy aging?