Tolerance and Efficacy of a New Enteral Formula Specifically Designed for Elderly Persons: An Experimental Study in the Aged Rat

For the first time, a formula was specifically designed for the nutritional support of tube-fed elderly patients (Elderly-Specific Formula [ESF], Nestlé, Switzerland). It was tested against a standard formula (Sondalis Iso [SI], Nestle ́ Clinical Nutrition, Marne la Vallée, France) in sixteen 22-month-old Sprague Dawley rats fed by total continuous enteral infusion for 7 days. Body weight, stool weight, and nitrogen balance were measured daily. After death, muscle weight, plasma levels of amino acids, tissue protein, and amino acid content were measured. The ESF curbed weight loss, improved cumulative nitrogen balance, and increased jejunum protein content. Plasma levels of threonine, leucine, and isoleucine and the sum of total amino acids were higher in ESF-fed than in SF-fed rats. Threonine and isoleucine content in the soleus and gastrocnemius were higher in ESF-fed rats than SI-fed ones. ESF improved intestinal transit. Thus, in old rats, the ESF favored nutritional status more than a standard formula. Key Words: Enteral nutrition—Whey protein—Nitrogen balance—Amino acids—Aged rat. AGING alters the control of metabolic homeostasisand generates specific nutritional requirements. More specifically, protein homeostasis in aging muscle is threatened by an imbalance between catabolism an