title: Protein Requirements during Aging.
abstract: Protein recommendations for elderly, both men and women, are based on nitrogen balance studies. They are set at 0.66 and 0.8 g/kg/day as the estimated average requirement (EAR) and recommended dietary allowance (RDA), respectively, similar to young adults. This recommendation is based on single linear regression of available nitrogen balance data obtained at test protein intakes close to or below zero balance. Using the indicator amino acid oxidation (IAAO) method, we estimated the protein requirement in young adults and in both elderly men and women to be 0.9 and 1.2 g/kg/day as the EAR and RDA, respectively. This suggests that there is no difference in requirement on a gender basis or on a per kg body weight basis between younger and older adults. The requirement estimates however are ~40% higher than the current protein recommendations on a body weight basis. They are also 40% higher than our estimates in young men when calculated on the basis of fat free mass. Thus, current recommendations may need to be re-assessed. Potential rationale for this difference includes a decreased sensitivity to dietary amino acids and increased insulin resistance in the elderly compared with younger individuals.
authors.affiliation: Research Institute, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada. glenda.courtney-martin@sickkids.ca.|Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, ON M5S 2W6, Canada. glenda.courtney-martin@sickkids.ca.
authors.forename: Glenda
authors.initials: G
authors.lastname: Courtney-Martin
authors.affiliation: Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2R3, Canada. ron.ball@ualberta.ca.
authors.forename: Ronald O
authors.initials: RO
authors.lastname: Ball
authors.affiliation: Research Institute, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada. paul.pencharz@sickkids.ca.|Department of Paediatrics, University of Toronto, Toronto, ON M5G 1X8, Canada. paul.pencharz@sickkids.ca.|Nutritional Sciences, University of Toronto, Toronto, ON M5S 3E2, Canada. paul.pencharz@sickkids.ca.
authors.forename: Paul B
authors.initials: PB
authors.lastname: Pencharz
authors.affiliation: Department of Pediatrics, University of British Columbia, Vancouver, BC V6H 3V4, Canada. relango@cfri.ubc.ca.|Research Institute, BC Children's Hospital, Vancouver, BC V5Z 4H4, Canada. relango@cfri.ubc.ca.|School of Population and Public Health, University of British Columbia, Vancouver, BC V6T 1Z3, Canada. relango@cfri.ubc.ca.
authors.forename: Rajavel
authors.initials: R
authors.lastname: Elango
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001835:Body Weight; D004044:Dietary Proteins / Q000008:administration & dosage* / Q000592:standards; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010084:Oxidation-Reduction; D064167:Recommended Dietary Allowances; D055815:Young Adult
chemical_list: D004044:Dietary Proteins
keywords: elderly; indicator amino acid oxidation; protein; requirements