Protein and healthy aging234

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ABSTRACT

Our understanding of the potential benefits and challenges of optimizing dietary protein intake in older adults continues to evolve. An overarching hypothesis generated during Protein Summit 2.0 was that consuming an adequate amount of high-quality protein at each meal, in combination with physical activity, may delay the onset of sarcopenia, slow its progression, reduce the magnitude of its functional consequences, or all of these. The potential benefits of young and middle-aged adults adopting a diet pattern whereby adequate protein is consumed at each meal as a countermeasure to sarcopenia are presented and discussed. For example, meeting a protein threshold (∼25–30 g/meal) represents a promising, yet still largely unexplored dietary strategy to help maintain muscle mass and function. For many older adults, breakfast is a carbohydrate-dominated lower-protein meal and represents an opportunity to improve and more evenly distribute daily protein intake. Although both animal and plant-based proteins can provide the required essential amino acids for health, animal proteins generally have a higher proportion of the amino acid leucine. Leucine plays a key role in stimulating translation initiation and muscle protein anabolism and is the focus of ongoing research. Protein requirements should be assessed in the light of habitual physical activity. An evenly distributed protein diet provides a framework that allows older adults to benefit from the synergistic anabolic effect of protein and physical activity. To fully understand the role of dietary protein intake in healthy aging, greater efforts are needed to coordinate and integrate research design and data acquisition and interpretation from a variety of disciplines.

Keywords:

dietary requirements
muscle
nutrition
protein
sarcopenia

ABBREVIATIONS

AMPK
AMP-activated protein kinase
eEF2
eukaryotic elongation factor 2
mTOR
mammalian target of rapamycin
RDA
Recommended Dietary Allowance
S6K1
ribosomal protein S6 kinase β1
4E-BP1
eukaryotic translation initiation factor 4E-binding protein 1

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2

Presented at the conference “Protein Summit 2.0: Evaluating the Role of Protein in Public Health,” held in Washington, DC, 2 October 2013.

3

Protein Summit 2.0 was hosted by Purdue University, Ingestive Behavior Research Center; the University of Missouri, Department of Nutrition and Exercise Physiology; the Nutritional Center for Health; and the Reynolds Institute on Aging, University of Arkansas for Medical Sciences.

4

Protein Summit 2.0 and this supplement were supported by funding from The Beef Checkoff, Dairy Research Institute, Egg Nutrition Center, Global Dairy Platform, Hillshire Brands, and the National Pork Board. Responsibility for the design, implementation, analysis, and interpretation of the information presented in this review was that of the authors.