title: Diet quality is associated with circulating C-reactive protein but not irisin levels in humans.
abstract: OBJECTIVE
  Adherence to a healthy diet has been shown to decrease the incidence of obesity and associated comorbidities. C-reactive protein (CRP) is an established inflammatory marker and irisin was recently identified as a molecule which may play a role in energy regulation and obesity but whether diet alters irisin levels remains unknown. We aimed to investigate the association between circulating irisin, leptin, and CRP levels and dietary quantity and quality using the Alternate Healthy Eating Index (AHEI) and the Alternate Mediterranean Diet Score (aMED).
  
  
  METHODS
  The study evaluated dietary data and biomarker levels of 151 participants between 2009 and 2011 (71 male vs. 80 female, over 35 years old, obese 43.7%). AHEI and aMED scores were calculated based on data derived from self-administered 110-item food-frequency questionnaires estimating usual nutrient intake over the past year. Cross-sectional associations between dietary quantity, quality, body composition by bioelectric impedance, and biomarker levels including irisin, leptin, and CRP after fasting were assessed.
  
  
  RESULTS
  CRP, but not irisin, was negatively correlated with AHEI (r=-0.34) and aMED (r=-0.31). Irisin was positively correlated with BMI (r=0.22), fat mass (r=0.21), waist circumference (r=0.24), waist-hip ratio (r=0.20), leptin (r=0.32), and CRP (r=0.25). Participants with the highest AHEI scores tended to have 11.6% lower concentrations of irisin (P for trend =0.09), but they were not significant after adjustment for potential confounders. Better diet quality was associated with lower CRP concentrations (P for trend=0.02) in multivariate model. Percentage of energy from carbohydrate was inversely associated with CRP.
  
  
  CONCLUSIONS
  Unlike CRP, irisin is not associated with dietary quality or quantity.
authors: Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA; Department of Family Medicine, Hallym University Sacred Heart Hospital, Hallym University, Gyeonggi-do, 431-796, Korea. Electronic address: beloved920@gmail.com.
authors: Kyung Hee
authors: KH
authors: Park
authors: Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
authors: Lesya
authors: L
authors: Zaichenko
authors: Department of Internal Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215.
authors: Patricia
authors: P
authors: Peter
authors: Judge Baker Children's Center, Boston, MA.
authors: Cynthia R
authors: CR
authors: Davis
authors: Judge Baker Children's Center, Boston, MA; Department of Psychiatry and Behavioral Science, Stony Brook University School of Medicine, Stony Brook, NY.
authors: Judith A
authors: JA
authors: Crowell
authors: Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA; Section of Endocrinology, Boston VA Healthcare System, Harvard Medical School, Boston, MA 02130, USA.
authors: Christos S
authors: CS
authors: Mantzoros
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D001823:Body Composition; D015992:Body Mass Index; D002097:C-Reactive Protein / Q000378:metabolism*; D003430:Cross-Sectional Studies; D038441:Diet, Mediterranean; D017097:Electric Impedance; D002149:Energy Intake; D005247:Feeding Behavior; D005260:Female; D005353:Fibronectins / Q000097:blood*; D006801:Humans; D020738:Leptin / Q000097:blood*; D008297:Male; D008875:Middle Aged
chemical_list: D015415:Biomarkers; C577593:FNDC5 protein, human; D005353:Fibronectins; D020738:Leptin; D002097:C-Reactive Protein
keywords: AHEI; Alternate Healthy Eating Index; Alternate Mediterranean Diet Score; BIDMC; BMI; Beth Israel Deaconess Medical Center; Body mass index; C-reactive protein; Dietary pattern; FFQ; Food Frequency Questionnaire; Irisin; MDS; Mediterranean Diet; Mediterranean Diet Score; WHR; aMED; waist–hip ratio.