title: Effects of Lowering Glycemic Index of Dietary Carbohydrate on Plasma Uric Acid Levels: The OmniCarb Randomized Clinical Trial.
abstract: The effects of carbohydrates on plasma uric acid levels are a subject of controversy. We determined the individual and combined effects of carbohydrate quality (the glycemic index) and quantity (the proportion of total daily energy [percentage of carbohydrates]) on uric acid levels.
  
  
  
  We conducted a randomized, crossover trial of 4 different diets in overweight or obese adults without cardiovascular disease (n = 163). Participants consumed each of 4 diets over a 5-week period, each of which was separated by a 2-week washout period. Body weight was kept constant. The 4 diets were high glycemic index (≥65) with high percentage of carbohydrates (58% kcal), low glycemic index (≤45) with low percentage of carbohydrates (40% kcal), low glycemic index with high percentage of carbohydrates, and high glycemic index with low percentage of carbohydrates. Plasma uric acid levels were measured at baseline and after completion of each 5-week period for comparison between the 4 diets.
  
  
  
  Of the 163 study participants, 52% were women and 50% were non-Hispanic African American subjects; their mean age was 52.6 years, and their mean ± SD uric acid level was 4.7 ± 1.2 mg/dl. Reducing the glycemic index lowered uric acid levels when the percentage of carbohydrates was low (-0.24 mg/dl; P < 0.001) or high (-0.17 mg/dl; P < 0.001). Reducing the percentage of carbohydrates marginally increased the uric acid level only when the glycemic index was high (P = 0.05). The combined effect of lowering the glycemic index and increasing the percentage of carbohydrates was -0.27 mg/dl (P < 0.001). This effect was observed even after adjustment for concurrent changes in kidney function, insulin sensitivity, and products of glycolysis.
  
  
  
  Reducing the glycemic index lowers uric acid levels. Future studies should examine whether reducing the glycemic index can prevent gout onset or flares.
authors.affiliation: Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Juraschek
authors.affiliation: Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.
authors.forename: Mara
authors.initials: M
authors.lastname: McAdams-Demarco
authors.affiliation: Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Allan C
authors.initials: AC
authors.lastname: Gelber
authors.affiliation: Harvard T. C. Chan School of Public Health and Brigham and Women's Hospital, Boston, Massachusetts.
authors.forename: Frank M
authors.initials: FM
authors.lastname: Sacks
authors.affiliation: Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Lawrence J
authors.initials: LJ
authors.lastname: Appel
authors.affiliation: Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Karen J
authors.initials: KJ
authors.lastname: White
authors.affiliation: Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Edgar R
authors.initials: ER
authors.lastname: Miller
mesh_terms: D000328:Adult; D001741:Black or African American; D001786:Blood Glucose / Q000378:metabolism; D002784:Cholesterol / Q000097:blood; D008076:Cholesterol, HDL / Q000097:blood; D018592:Cross-Over Studies; D055316:Cystatin C / Q000378:metabolism; D050528:Diet, Carbohydrate-Restricted; D004040:Dietary Carbohydrates; D005260:Female; D038321:Glycemic Index; D006630:Hispanic or Latino; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D019344:Lactic Acid / Q000097:blood; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood* / Q000378:metabolism; D050177:Overweight / Q000097:blood / Q000378:metabolism; D014280:Triglycerides / Q000097:blood; D014527:Uric Acid / Q000097:blood*; D044465:White People
chemical_list: D001786:Blood Glucose; D008076:Cholesterol, HDL; D055316:Cystatin C; D004040:Dietary Carbohydrates; D007328:Insulin; D014280:Triglycerides; D014527:Uric Acid; D019344:Lactic Acid; D002784:Cholesterol