title: The influence of body mass index and renin-angiotensin-aldosterone system activity on the relationship between 25-hydroxyvitamin D and adiponectin in Caucasian men.
abstract: OBJECTIVE
  Previous studies have suggested that circulating adiponectin concentrations are associated positively with vitamin D and negatively with body mass index (BMI) but have not accounted for the influence of the renin-angiotensin-aldosterone system (RAAS) in this relationship. This is particularly relevant because increased RAAS activity is associated with obesity and is known to lower adiponectin levels. We evaluated the association between adiponectin and 25-hydroxyvitamin D (25(OH)D) after controlling RAAS activity with dietary sodium equilibration and also evaluated whether this relationship was influenced by BMI.
  
  
  METHODS
  Cross-sectional study of 115 hypertensive Caucasian men from the Hypertensive Pathotype Consortium.
  
  
  METHODS
  To manipulate RAAS activity, all subjects underwent 1 week of high dietary sodium (HS) diet to suppress RAAS and 1 week of low dietary sodium (LS) diet to stimulate RAAS. Linear regression was used to evaluate the association between adiponectin and 25(OH)D, and the effect of BMI on this relationship, in each dietary condition.
  
  
  RESULTS
  Adiponectin was higher on HS, where circulating RAAS activity was low, when compared with LS (HS=2.9 versus LS=2.4 μg/ml, P<0.0001). 25(OH)D levels were positively associated with adiponectin, and BMI was a statistically significant effect modifier of the relationship between 25(OH)D and adiponectin on both diets (P interaction <0.01 between BMI and 25(OH)D).
  
  
  CONCLUSIONS
  Higher 25(OH)D concentrations were independently associated with higher adiponectin levels, particularly when BMI was high. Dietary sodium balance and circulating RAAS activity did not appear to affect this relationship. Future studies should explore whether vitamin D supplementation increases adiponectin levels in obesity.
authors.affiliation: Division of Endocrinology, Diabetes, and Hypertension, Brigham and Women's Hospital, 221 Longwood Avenue, RFB 386, Boston, Massachusetts 02115, USA. avaidya1@partners.org
authors.forename: Anand
authors.initials: A
authors.lastname: Vaidya
authors.forename: John P
authors.initials: JP
authors.lastname: Forman
authors.forename: Patricia C
authors.initials: PC
authors.lastname: Underwood
authors.forename: Paul N
authors.initials: PN
authors.lastname: Hopkins
authors.forename: Gordon H
authors.initials: GH
authors.lastname: Williams
authors.forename: Luminita H
authors.initials: LH
authors.lastname: Pojoga
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Williams
mesh_terms: D052242:Adiponectin / Q000097:blood*; D000273:Adipose Tissue / Q000502:physiology; D000328:Adult; D000368:Aged; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D006887:Hydroxycholecalciferols / Q000097:blood*; D006973:Hypertension / Q000097:blood; D007333:Insulin Resistance / Q000502:physiology; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D012084:Renin-Angiotensin System / Q000502:physiology*; D012982:Sodium, Dietary / Q000494:pharmacology; D044465:White People
chemical_list: D052242:Adiponectin; D006887:Hydroxycholecalciferols; D012982:Sodium, Dietary