*Article* **Influence of Diets with Varying Essential**/**Nonessential Amino Acid Ratios on Mouse Lifespan**

**Claudia Romano 1,**†**, Giovanni Corsetti 1, \*,**†**, Vincenzo Flati 2,**†**, Evasio Pasini 3, Anna Picca 4,5, Riccardo Calvani 4,5, Emanuele Marzetti 4 and Francesco Saverio Dioguardi 6, \***


Received: 27 March 2019; Accepted: 13 June 2019; Published: 18 June 2019

**Abstract:** An adequate intake of essential (EAA) and non-essential amino acids (NEAA) is crucial to preserve cell integrity and whole-body metabolism. EAA introduced with diet may be insu fficient to meet the organismal needs, especially under increased physiological requirements or in pathological conditions, and may condition lifespan. We therefore examined the e ffects of iso-caloric and providing the same nitrogenous content diets, any diet containing di fferent stoichiometric blends of EAA/NEAA, on mouse lifespan. Three groups of just-weaned male Balb/C mice were fed exclusively with special diets with varying EAA/NEAA ratios, ranging from 100%/0% to 0%/100%. Three additional groups of mice were fed with di fferent diets, two based on casein as alimentary proteins, one providing the said protein, one reproducing the amino acidic composition of casein, and the third one, the control group, was fed by a standard laboratory diet. Mouse lifespan was inversely correlated with the percentage of NEAA introduced with each diet. Either limiting EAA, or exceeding NEAA, induced rapid and permanent structural modifications on muscle and adipose tissue, independently of caloric intake. These changes significantly a ffected food and water intake, body weight, and lifespan. Dietary intake of varying EAA/NEAA ratios induced changes in several organs and profoundly influenced murine lifespan. The balanced content of EAA provided by dietary proteins should be considered as the preferable means for "optimal" nutrition and the elevated or unbalanced intake of NEAA provided by food proteins may negatively a ffect the health and lifespan of mice.

**Keywords:** amino acids intake; essential amino acids; diet; extended lifespan; mice
