title: Effect of age on substrate oxidation during total parenteral nutrition.
abstract: OBJECTIVE
  Parenteral nutrition is increasingly used in the elderly. Aging is accompanied by metabolic changes that can modify substrate use. We compared substrate oxidation during cyclic total parenteral nutrition (TPN) in elderly and middle-aged patients.
  
  
  METHODS
  Twelve elderly patients (eight women, four men; 72 +/- 5 y) and 12 middle-aged patients (nine women, three men; 39 +/- 13 y) who were on cyclic TPN for intestinal failure were investigated while in stable condition after at least 15 d of TPN. No patient was diabetic. Indirect calorimetry was performed during fasting and every 30 min during the 3 h of TPN infusion and 3 h after infusion, allowing the measurement of nutrient oxidation. Blood samples were obtained every hour for the measurement of glucose, insulin, triacylglycerols, and free fatty acids.
  
  
  RESULTS
  In the fasting state, resting energy expenditure was significantly higher in the elderly patients than in the middle-aged patients (39.3 +/- 8.1 versus 31.9 +/- 4.3 kcal/kg of fat-free mass per day, P = 0.008). During TPN, lipid oxidation was significantly higher in the elderly patients than in the middle-aged patients (1.09 +/- 0.17 versus 0.84 +/- 0.27 mg x kg(-1) x min(-1), P = 0.011); glucose oxidation was significantly lower in the elderly patients than in the middle-aged patients (2.19 +/- 0.93 versus 3.22 +/- 1.54 mg x kg(-1) x min(-1), P = 0.038). Areas under the curves of glycemia and free fatty acids were significantly higher in the elderly patients.
  
  
  CONCLUSIONS
  In the elderly, TPN was associated with significantly higher lipid oxidation and lower glucose oxidation than in younger patients. TPN formulas and flow rates should therefore be adapted in the elderly.
authors.affiliation: Department of Gastroenterology, Unit of Nutrition, Archet Hospital, Nice, France.
authors.forename: Rima
authors.initials: R
authors.lastname: Al-Jaouni
authors.forename: Stephane M
authors.initials: SM
authors.lastname: Schneider
authors.forename: Patrick
authors.initials: P
authors.lastname: Rampal
authors.forename: Xavier
authors.initials: X
authors.lastname: Hébuterne
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000378:metabolism*; D019540:Area Under Curve; D001481:Basal Metabolism / Q000502:physiology; D001786:Blood Glucose / Q000032:analysis / Q000378:metabolism*; D001823:Body Composition; D002153:Calorimetry, Indirect; D004734:Energy Metabolism / Q000502:physiology*; D005215:Fasting; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D006801:Humans; D007328:Insulin / Q000097:blood / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D010084:Oxidation-Reduction; D010289:Parenteral Nutrition, Total; D014280:Triglycerides / Q000097:blood / Q000378:metabolism*
chemical_list: D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D014280:Triglycerides