title: Protein and amino acid requirements of the elderly.
abstract: This paper has reviewed changes in body composition and protein metabolism that are associated with aging. Body protein mass decreases. Rates of both muscle and whole-body protein turnover/kg body weight decrease, and the percentage of turnover contributed by muscle to whole-body turnover decreases with age. Total plasma proteins, albumin, prealbumin, transferrin and ceruloplasmin levels decline with age, and, in the case of albumin levels, the decline continues when young-old are compared with old-old. Protein requirement of the elderly appears to have been underestimated by the factorial method. Nitrogen balance studies indicate a minimum of 0.7 g protein/kg/day in one study. Several studies show 0.8 g, whereas other studies show negative nitrogen balance at this level. The recommended protein intake is 1 g protein/kg/day, and 12-14% of total calories should be provided by protein. The few nitrogen balance studies that attempted to determine essential amino acid requirements are limited and contradictory.
authors.affiliation: Department of Nutrition and Dietetics, Georgia State University, Atlanta 30303.
authors.forename: J
authors.initials: J
authors.lastname: Prothro
mesh_terms: D000368:Aged; D000375:Aging / Q000378:metabolism*; D000596:Amino Acids / Q000378:metabolism*; D001798:Blood Proteins / Q000378:metabolism; D001823:Body Composition; D003404:Creatinine / Q000652:urine; D004044:Dietary Proteins / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D008762:Methylhistidines / Q000652:urine; D009132:Muscles / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism; D011506:Proteins / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D001798:Blood Proteins; D004044:Dietary Proteins; D008762:Methylhistidines; D011506:Proteins; D003404:Creatinine; D009584:Nitrogen