title: Age-related changes in basal substrate oxidation and visceral adiposity and their association with metabolic syndrome.
abstract: OBJECTIVE
  Ageing is directly associated with visceral fat (VAT) deposition and decline of metabolically active cellular mass, which may determine age-related shifts in substrate oxidation and increased cardiometabolic risk. We tested whether VAT and fasting respiratory quotient (RQ, an index of macronutrient oxidation) changed with age and if they were associated with increased risk of metabolic syndrome (MetSyn).
  
  
  METHODS
  A total of 2819 adult participants (age range: 18-81 years; men/women: 894/1925) were included; we collected history, anthropometric measures, biochemistry, smoking habits, and physical activity. The body mass index range was 18.5-60.2 kg/m(2). Gas exchanges (VO2 and VCO2) were measured by indirect calorimetry in fasting conditions, and RQ was calculated. Body composition was measured by bioelectrical impedance. Abdominal subcutaneous fat and VAT were measured by ultrasonography. MetSyn was diagnosed using harmonised international criteria. Multivariate linear and logistic regression models were utilised.
  
  
  RESULTS
  VAT increased with age in both men (r = 0.31, p < 0.001) and women (r = 0.37, p < 0.001). Basal RQ was not significantly associated with age (p = 0.49) and VAT (p = 0.20); in addition, basal RQ was not a significant predictor of MetSyn (OR 3.31, 0.57-19.08, p = 0.27). VAT was the primary predictor of MetSyn risk in a fully adjusted logistic model (OR 4.25, 3.01-5.99, p < 0.001).
  
  
  CONCLUSIONS
  Visceral adiposity remains one of the most important risk factors for cardiometabolic risk and is a significant predictor of MetSyn. Post-absorptive substrate oxidation does not appear to play a significant role in age-related changes in body composition and cardiometabolic risk, except for a correlation with triglyceride concentration.
authors.affiliation: Human Nutrition Research Centre, Institute of Cellular Medicine, Newcastle University, Campus for Ageing and Vitality, Newcastle on Tyne, NE4 5PL, UK. mario.siervo@ncl.ac.uk.|MRC Human Nutrition Research, Fulbourn Road, Cambridge, CB1 9NL, UK. mario.siervo@ncl.ac.uk.
authors.forename: Mario
authors.initials: M
authors.lastname: Siervo
authors.affiliation: Human Nutrition Research Centre, Institute of Cellular Medicine, Newcastle University, Campus for Ageing and Vitality, Newcastle on Tyne, NE4 5PL, UK.
authors.forename: Jose
authors.initials: J
authors.lastname: Lara
authors.affiliation: Human Nutrition Research Centre, Institute of Cellular Medicine, Newcastle University, Campus for Ageing and Vitality, Newcastle on Tyne, NE4 5PL, UK.
authors.forename: Carlos
authors.initials: C
authors.lastname: Celis-Morales
authors.affiliation: MRC Human Nutrition Research, Fulbourn Road, Cambridge, CB1 9NL, UK.
authors.forename: Michele
authors.initials: M
authors.lastname: Vacca
authors.affiliation: Human Nutrition Research Centre, Institute of Cellular Medicine, Newcastle University, Campus for Ageing and Vitality, Newcastle on Tyne, NE4 5PL, UK.
authors.forename: Clio
authors.initials: C
authors.lastname: Oggioni
authors.affiliation: International Center for the Assessment of Nutritional Status (ICANS), Department of Food, Environmental and Nutritional Sciences (DeFENS), University of Milan, Sandro Botticelli, 21, 20133, Milan, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Battezzati
authors.affiliation: International Center for the Assessment of Nutritional Status (ICANS), Department of Food, Environmental and Nutritional Sciences (DeFENS), University of Milan, Sandro Botticelli, 21, 20133, Milan, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Leone
authors.affiliation: Human Nutrition and Eating Disorders Research Centre, Department of Public Health, Experimental and Forensic Medicine, University of Pavia, Via Bassi, 21, 27100, Pavia, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Tagliabue
authors.affiliation: International Center for the Assessment of Nutritional Status (ICANS), Department of Food, Environmental and Nutritional Sciences (DeFENS), University of Milan, Sandro Botticelli, 21, 20133, Milan, Italy.
authors.forename: Angela
authors.initials: A
authors.lastname: Spadafranca
authors.affiliation: International Center for the Assessment of Nutritional Status (ICANS), Department of Food, Environmental and Nutritional Sciences (DeFENS), University of Milan, Sandro Botticelli, 21, 20133, Milan, Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Bertoli
mesh_terms: D050154:Adiposity; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D001823:Body Composition; D015992:Body Mass Index; D002318:Cardiovascular Diseases / Q000453:epidemiology; D003430:Cross-Sectional Studies; D017097:Electric Impedance; D015444:Exercise; D005260:Female; D006801:Humans; D050152:Intra-Abdominal Fat / Q000378:metabolism; D016015:Logistic Models; D008297:Male; D024821:Metabolic Syndrome / Q000453:epidemiology*; D008875:Middle Aged; D056128:Obesity, Abdominal / Q000453:epidemiology*; D011659:Pulmonary Gas Exchange; D012307:Risk Factors; D014280:Triglycerides / Q000097:blood; D055105:Waist Circumference; D055815:Young Adult
chemical_list: D014280:Triglycerides
keywords: Ageing; Body composition; Indirect calorimetry; Metabolic risk; Substrate oxidation