title: Effects of intraduodenal hydroxycitrate on glucose absorption, incretin release, and glycemia in response to intraduodenal glucose infusion in health and type 2 diabetes: A randomised controlled trial.
abstract: OBJECTIVE
  Hydroxycitric acid (HCA), derived from the fruit Garcinia cambogia, reduces the rate of glucose absorption and lowers postprandial glycemia in rodents, but its effect in humans is unknown. The aim of this study was to investigate the effects of small intestinal perfusion with HCA on glucose absorption, as well as the incretin and glycemic responses to a subsequent intraduodenal glucose infusion, in both healthy individuals and patients with type 2 diabetes.
  
  
  METHODS
  Twelve healthy participants and 8 patients with type 2 diabetes received an intraduodenal infusion of HCA (2800 mg in water) or control (water) over 60 min, followed by an intraduodenal infusion of 60 g glucose over 120 min, in a double-blind, randomized crossover design. In healthy individuals, 5 g 3-O-methylglucose (3-OMG) was co-infused with glucose as a marker of glucose absorption. Blood was sampled frequently.
  
  
  RESULTS
  In healthy individuals, blood glucose was lower with HCA than control, both before and during the intraduodenal glucose infusion (P < 0.05 for each). Plasma glucose-dependent insulinotropic polypeptide (GIP; P = 0.01) and glucagon (P = 0.06) were higher with HCA, but there were no differences in plasma glucagon-like peptide (GLP)-1, insulin, or serum 3-OMG concentrations. In patients with type 2 diabetes, blood glucose, and plasma GIP, GLP-1, and insulin did not differ between HCA and control either before or after intraduodenal glucose, but during glucose infusion, plasma glucagon was higher with HCA (P = 0.04).
  
  
  CONCLUSIONS
  In healthy individuals, small intestinal exposure to HCA resulted in a modest reduction in glycemia and stimulation of plasma GIP and glucagon, but no effect on plasma GLP-1 or insulin, or on glucose absorption. HCA had no effect on glycemia in patients with type 2 diabetes.
authors.affiliation: Discipline of Medicine, The University of Adelaide, Royal Adelaide Hospital, Adelaide, Australia; Centre of Research Excellence in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, Australia.
authors.forename: Sony S
authors.initials: SS
authors.lastname: Thazhath
authors.affiliation: Discipline of Medicine, The University of Adelaide, Royal Adelaide Hospital, Adelaide, Australia; Centre of Research Excellence in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, Australia.
authors.forename: Tongzhi
authors.initials: T
authors.lastname: Wu
authors.affiliation: Discipline of Medicine, The University of Adelaide, Royal Adelaide Hospital, Adelaide, Australia; Centre of Research Excellence in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, Australia.
authors.forename: Michelle J
authors.initials: MJ
authors.lastname: Bound
authors.affiliation: Discipline of Medicine, The University of Adelaide, Royal Adelaide Hospital, Adelaide, Australia; Centre of Research Excellence in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, Australia.
authors.forename: Helen L
authors.initials: HL
authors.lastname: Checklin
authors.affiliation: Discipline of Medicine, The University of Adelaide, Royal Adelaide Hospital, Adelaide, Australia; Centre of Research Excellence in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, Australia.
authors.forename: Scott
authors.initials: S
authors.lastname: Standfield
authors.affiliation: Discipline of Medicine, The University of Adelaide, Royal Adelaide Hospital, Adelaide, Australia; Centre of Research Excellence in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, Australia.
authors.forename: Karen L
authors.initials: KL
authors.lastname: Jones
authors.affiliation: Discipline of Medicine, The University of Adelaide, Royal Adelaide Hospital, Adelaide, Australia; Centre of Research Excellence in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, Australia; Endocrine and Metabolic Unit, Royal Adelaide Hospital, Adelaide, Australia.
authors.forename: Michael
authors.initials: M
authors.lastname: Horowitz
authors.affiliation: Discipline of Medicine, The University of Adelaide, Royal Adelaide Hospital, Adelaide, Australia; Centre of Research Excellence in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, Australia; Department of Gastroenterology and Hepatology, Royal Adelaide Hospital, Adelaide, Australia. Electronic address: chris.rayner@adelaide.edu.au.
authors.forename: Christopher K
authors.initials: CK
authors.lastname: Rayner
mesh_terms: D019325:3-O-Methylglucose / Q000097:blood / Q000378:metabolism; D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood / Q000378:metabolism; D002951:Citrates / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D018592:Cross-Over Studies; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000178:diet therapy* / Q000378:metabolism; D004040:Dietary Carbohydrates / Q000008:administration & dosage / Q000378:metabolism*; D019587:Dietary Supplements / Q000009:adverse effects; D004311:Double-Blind Method; D004386:Duodenum / Q000378:metabolism; D005260:Female; D005947:Glucose / Q000008:administration & dosage / Q000378:metabolism*; D006801:Humans; D006943:Hyperglycemia / Q000517:prevention & control; D007004:Hypoglycemic Agents / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D054795:Incretins / Q000097:blood / Q000378:metabolism*; D007408:Intestinal Absorption; D007413:Intestinal Mucosa / Q000378:metabolism; D007441:Intubation, Gastrointestinal; D008297:Male; D008875:Middle Aged
chemical_list: D015415:Biomarkers; D002951:Citrates; D004040:Dietary Carbohydrates; D007004:Hypoglycemic Agents; D054795:Incretins; D019325:3-O-Methylglucose; C007999:hydroxycitric acid; D005947:Glucose
keywords: 3-O-Methylglucose; Garcinia cambogia; Glucagon-like peptide-1; Glucose absorption; Glucose-dependent insulinotropic polypeptide; Hydroxycitric acid; Incretin hormones; Postprandial glucose