http://www.baldingblog.com/2010/04/05/reader-says-dht-is-overrated-focus-should-be-on-igf-1/
http://www.impactaging.com/papers/v5/n7/full/100581.html
Accumulating data suggest that protein intake and dietary aminoacid composition play an important role in regulating mTOR activity, serum IGF-1 concentrations, and longevity [2,38,49-54]. Our data show that in humans, unlike in rodents, severe CR does not reduce serum IGF-1 concentration unless protein intake is also reduced close to the USDA recommended intake (i.e. 10% calories from protein, or 0.8 g/kg/day) [38]. Data from genetic animal and human studies indicate that serum IGF-1 concentration is an important regulator of aging [2,55-56], and has been found to be inversely correlated with median lifespan in 31 genetically diverse inbred mouse strains [57]. Interestingly, back in 1950 the Okinawan centenarians were consuming a CR diet (approximately 1800 cal/day) with only 9% of calories coming from protein [58]. In contrast, both the WNPRC and NIA monkey diets contain 15% or more calorie from protein, which is similar to the average protein intake of US men and women [59], and may explain why serum IGF-1 concentrations were similar between CR and control monkeys. More studies are needed to understand the role of protein intake (and aminoacid composition of foods) with and without CR in regulating the pro-longevity PI3K/AKT and mTOR pathways in rodents and primates. The old dogma that only calorie intake, and not macronutrient composition (and in particular protein intake), is an important regulator of lifespan is based on a flawed interpretation of a study published by the Masoro's group in 1985.