title: Roasting intensity of naturally low-caffeine Laurina coffee modulates glucose metabolism and redox balance in humans.
abstract: OBJECTIVE
  Coffee consumption is negatively associated with risk of type 2 diabetes and cardiovascular mortality. Coffee roasting can greatly modify the quality-quantitative characteristics of bioactive compounds. We compared the effects of two different roasting intensities of the same naturally low-caffeine Arabica coffee variety (Laurina) on glucose and lipid metabolism as well as oxidative stress.
  
  
  METHODS
  We performed a double-blind, crossover intervention study. Fourteen healthy male volunteers consumed four cups daily of light roasted coffee (LRC) and dark roasted coffee (DRC), each for 1 wk (intervention period 1 and 2 respectively). One wk washout, with total abstinence from coffee and other possible caffeine sources, preceded each intervention. Data were collected at the end of washout and intervention periods.
  
  
  RESULTS
  Changes between washout and intervention periods in glucose concentrations at 2 h post-oral glucose tolerance test, were significantly lower after DRC than LRC intake (-0.6 ± 0.3 and 0.4 ± 0.3 mmol/L, P < 0.03). Changes in β-cell function, assessed as insulin secretion-sensitivity index-2, were significantly greater after DRC than LRC (34.7 ± 25.0 and -18.8 ± 21.0, P = 0.03). The initial (30 min) post-oral glucose tolerance test area under the curve of glucagon-like peptide-1 was 24± 9% greater (P = 0.03) after DRC than LRC. LRC or DRC did not affect insulin sensitivity. Changes from basal of reduced-to-oxidized glutathione ratio (GSH/GSSG) in erythrocytes were significantly greater after DRC than LRC (+1437 ± 371 and -152 ± 30, P < 0.05). The omega-3 index in erythrocyte membranes was 16± 4% greater (P < 0.001) after DRC than LRC.
  
  
  CONCLUSIONS
  DRC consumption improved postload glucose metabolism by increasing incretin and insulin secretions. DRC compared to LRC improved redox balance and increased omega-3 fatty acids. Thus, we suggest greater metabolic benefits related to DRC.
authors.affiliation: Department of Medical, Surgical and Health Sciences, Clinica Medica AOUTS, University of Trieste, Trieste, Italy.
authors.forename: Filippo Giorgio
authors.initials: FG
authors.lastname: Di Girolamo
authors.affiliation: Department of Medical, Surgical and Health Sciences, Clinica Medica AOUTS, University of Trieste, Trieste, Italy.
authors.forename: Sara
authors.initials: S
authors.lastname: Mazzucco
authors.affiliation: Department of Medical, Surgical and Health Sciences, Clinica Medica AOUTS, University of Trieste, Trieste, Italy.
authors.forename: Roberta
authors.initials: R
authors.lastname: Situlin
authors.affiliation: Institute for Kinesiology Research, Science and Research Center of Koper, University of Primorska, Koper, Slovenia.
authors.forename: Nina
authors.initials: N
authors.lastname: Mohorko
authors.affiliation: Faculty of Health Sciences, University of Primorska, Izola, Slovenia.
authors.forename: Zala
authors.initials: Z
authors.lastname: Jenko-Pražnikar
authors.affiliation: Faculty of Health Sciences, University of Primorska, Izola, Slovenia.
authors.forename: Ana
authors.initials: A
authors.lastname: Petelin
authors.affiliation: Department of Medical, Surgical and Health Sciences, Clinica Medica AOUTS, University of Trieste, Trieste, Italy.
authors.forename: Marcello
authors.initials: M
authors.lastname: Tence
authors.affiliation: Institute for Kinesiology Research, Science and Research Center of Koper, University of Primorska, Koper, Slovenia.
authors.forename: Rado
authors.initials: R
authors.lastname: Pišot
authors.affiliation: illycaffè S.p.A., Trieste, Italy.
authors.forename: Luciano
authors.initials: L
authors.lastname: Navarini
authors.affiliation: Department of Medical, Surgical and Health Sciences, Clinica Medica AOUTS, University of Trieste, Trieste, Italy. Electronic address: biolo@units.it.
authors.forename: Gianni
authors.initials: G
authors.lastname: Biolo
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000378:metabolism*; D002110:Caffeine; D040503:Coffea / Q000737:chemistry / Q000378:metabolism*; D003069:Coffee / Q000737:chemistry / Q000378:metabolism*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005511:Food Handling / Q000379:methods*; D006358:Hot Temperature; D006801:Humans; D008297:Male; D010084:Oxidation-Reduction
chemical_list: D001786:Blood Glucose; D003069:Coffee; D002110:Caffeine
keywords: Coffee; Insulin resistance; Omega-3 fatty acids; Oxidative stress; Roasting intensity; Type-2 diabetes mellitus