title: Dietary ascorbic acid and subsequent change in body weight and waist circumference: associations may depend on genetic predisposition to obesity--a prospective study of three independent cohorts.
abstract: BACKGROUND
  Cross-sectional data suggests that a low level of plasma ascorbic acid positively associates with both Body Mass Index (BMI) and Waist Circumference (WC). This leads to questions about a possible relationship between dietary intake of ascorbic acid and subsequent changes in anthropometry, and whether such associations may depend on genetic predisposition to obesity. Hence, we examined whether dietary ascorbic acid, possibly in interaction with the genetic predisposition to a high BMI, WC or waist-hip ratio adjusted for BMI (WHR), associates with subsequent annual changes in weight (∆BW) and waist circumference (∆WC).
  
  
  METHODS
  A total of 7,569 participants' from MONICA, the Diet Cancer and Health study and the INTER99 study were included in the study. We combined 50 obesity associated single nucleotide polymorphisms (SNPs) in four genetic scores: a score of all SNPs and a score for each of the traits (BMI, WC and WHR) with which the SNPs associate. Linear regression was used to examine the association between ascorbic acid intake and ΔBW or ΔWC. SNP-score × ascorbic acid interactions were examined by adding product terms to the models.
  
  
  RESULTS
  We found no significant associations between dietary ascorbic acid and ∆BW or ∆WC. Regarding SNP-score × ascorbic acid interactions, each additional risk allele of the 14 WHR associated SNPs associated with a ∆WC of 0.039 cm/year (P = 0.02, 95% CI: 0.005 to 0.073) per 100 mg/day higher ascorbic acid intake. However, the association to ∆WC only remained borderline significant after adjustment for ∆BW.
  
  
  CONCLUSIONS
  In general, our study does not support an association between dietary ascorbic acid and ∆BW or ∆WC, but a diet with a high content of ascorbic acid may be weakly associated to higher WC gain among people who are genetically predisposed to a high WHR. However, given the quite limited association any public health relevance is questionable.
authors.affiliation: Institute of Preventive Medicine, Bispebjerg and Frederiksberg Hospitals, the Capital Region, Nordre Fasanvej 57, Hovedvejen, entrance 5, ground floor, 2000, Frederiksberg Copenhagen, Denmark. Sofus.Christian.Larsen@regionh.dk.
authors.forename: Sofus C
authors.initials: SC
authors.lastname: Larsen
authors.forename: Lars
authors.initials: L
authors.lastname: Angquist
authors.forename: Tarunveer Singh
authors.initials: TS
authors.lastname: Ahluwalia
authors.forename: Tea
authors.initials: T
authors.lastname: Skaaby
authors.forename: Nina
authors.initials: N
authors.lastname: Roswall
authors.forename: Anne
authors.initials: A
authors.lastname: Tjønneland
authors.forename: Jytte
authors.initials: J
authors.lastname: Halkjær
authors.forename: Kim
authors.initials: K
authors.lastname: Overvad
authors.forename: Oluf
authors.initials: O
authors.lastname: Pedersen
authors.forename: Torben
authors.initials: T
authors.lastname: Hansen
authors.forename: Allan
authors.initials: A
authors.lastname: Linneberg
authors.forename: Lise Lotte N
authors.initials: LL
authors.lastname: Husemoen
authors.forename: Ulla
authors.initials: U
authors.lastname: Toft
authors.forename: Berit L
authors.initials: BL
authors.lastname: Heitmann
authors.forename: Thorkild I A
authors.initials: TI
authors.lastname: Sørensen
mesh_terms: D001205:Ascorbic Acid / Q000008:administration & dosage*; D015992:Body Mass Index; D001835:Body Weight; D015331:Cohort Studies; D003718:Denmark; D004032:Diet; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide; D011446:Prospective Studies; D055105:Waist Circumference; D049629:Waist-Hip Ratio
chemical_list: D001205:Ascorbic Acid