Protein and Aging: Practicalities and Practice

Abstract

Dietary protein is an essential macronutrient derived from both plant and animal sources required for muscle building, immune function, and wound healing. However, in the United States, protein consumption worsens as individuals age, with 30% of men and 50% of women over 71 consuming inadequate dietary protein due to a variety of factors, including changes in gut function, loss of appetite, tooth loss, financial concerns, and social isolation. The aim of this review is to underscore the need for increased protein requirements in aging populations, highlight potential barriers, synthesize these protein requirements, and also recommend strategies to meet these increased protein needs. Achieving adequate protein status, especially when facing chronic or acute health concerns, is essential to promote muscle and bone strength (because aging is associated with significant decreases in postprandial muscle protein synthesis), to support immune health (due to immunosenescence), and to maintain a good quality of life. For older adults, the literature suggests that a dietary protein intake of at least 1.0-1.2 g/kg/day is required in healthy, aging populations, and intakes of 1.2-1.5 g/kg/day are necessary for those with chronic or acute conditions. These protein intake recommendations can increase to 2.0 g/kg/day in more severe cases of illness, malnutrition, and chronic conditions. The reviewed literature also suggests that evenly balanced protein distributions of 25-30 g of dietary protein (0.4 g/kg) per meal from animal and plant protein sources alike are sufficient to maximize muscle protein synthesis (MPS) rates in older populations. Additionally, pre-sleep protein feeds of 40 g/night may be another strategy to improve daily MPS and amino acid utilization.

Keywords: aging; animal and plant protein; chronic kidney disease; dietary protein; immunosenescence; muscle protein synthesis; older adults; pre-sleep protein feeds; protein intake distribution; sarcopenia.