title: Nutrient ingestion, protein intake, and sex, but not age, affect the albumin synthesis rate in humans.
abstract: The aim of this study was to assess the effects of nutrient ingestion, dietary protein intake, age, and sex on the fractional synthesis rate (FSR) of albumin. Thirty-six healthy free-living individuals (8 females and 10 males aged 21-43 y and 9 females and 9 males aged 63-79 y) completed three 18-d periods of controlled feeding with protein intakes of 125% (P125, 1.00 g protein x kg(-1) x d(-1)), 94% (P94, 0.75 g protein x kg(-1) x d(-1)), and 63% (P63, 0.50 g protein x kg(-1) x d(-1)) of the recommended dietary allowance. On d 12 of each trial, postabsorptive (PA) serum albumin concentration was determined and PA and postprandial (PP) albumin FSR were estimated from the rate of l-[1- 13C] leucine incorporation into plasma albumin during an 8-h infusion. There were no age-related differences in PA and PP albumin FSR. Albumin FSR was higher PP than PA (P < 0.0001), and the increase in albumin FSR from PA to PP was smaller as dietary protein intake decreased from P125 to P94 and P63 (P < 0.05). Independent of protein intake, males had a higher albumin FSR (P < 0.05) and a greater increase in albumin FSR with feeding (P < 0.05). There was no age or dietary protein effect on serum albumin concentrations, but males had higher albumin concentrations than females (P < 0.0001). These results show that older persons are responsive to nutrient ingestion and dietary protein-related changes in albumin FSR. The greater albumin synthesis rate in males might contribute to a higher albumin concentration set point.
authors.affiliation: Department of Foods and Nutrition, Purdue University, West Lafayette, IN 47906, USA.
authors.forename: Anna E
authors.initials: AE
authors.lastname: Thalacker-Mercer
authors.forename: Craig A
authors.initials: CA
authors.lastname: Johnson
authors.forename: Kevin E
authors.initials: KE
authors.lastname: Yarasheski
authors.forename: Nadine S
authors.initials: NS
authors.lastname: Carnell
authors.forename: Wayne W
authors.initials: WW
authors.lastname: Campbell
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology; D000418:Albumins / Q000096:biosynthesis*; D004032:Diet; D004044:Dietary Proteins / Q000008:administration & dosage* / Q000494:pharmacology*; D004734:Energy Metabolism / Q000187:drug effects; D005260:Female; D006801:Humans; D008297:Male; D012727:Sex Characteristics
chemical_list: D000418:Albumins; D004044:Dietary Proteins