Table 1.

Relationships among dietary protein intake, longevity and metabolic health.

	Effect of a LPHC diet on lifespan extension	Metabolic benefits of a LPHC diet or low protein intake	Ref.
	Ratio or proportion of protein to carbohydrate in food for lifespan extension
Drosophila melanogaster	Increased	Not determined	[63]
	P:C ratio = 1:16
Drosophila melanogaster	Increased	Not determined	[64]
	P:C ratio = 1:16
Queensland fruit flies	Increased	Not determined	[65]
	P:C ratio = 1:21
Crickets	Increased	Not determined	[66]
	P:C ratio = 1:3 (Male) P:C ratio = 1:8 (Female)
Mice	Increased	Insulin sensitivity↑, BP↓, HDL-C↑, TG↓, LDL-C↓, mTOR↓(liver), plasma BCAAs↓, mitochondrial function↑	[3]
	5% protein/75% carbohydrate, energy 13 kJ/g food

	The effect of LP intake on mortality	Metabolic benefits of low protein intake	Ref.
	Proportion of protein intake for reduced mortality
Humans	Aged 50 years or older: Diabetes-related mortality↓	Aged 50–65 years: Serum IGF-1↓ in LP intake group compared to IGF-1 in the HP intake group	[6]
	Aged 50–65 years: All-cause mortality↓, cancer-related mortality↓, LP intake is more effective than MP or HP intake.
		Aged 66 years or older: No change in serum IGF-1 levels between LP and HP intake groups.
	Aged 66 years or older: All-cause mortality↑, Cancer mortality↓ HP intake is more effective than LP intake.