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Nutrition. 2016 Sep;32(9):928-36. doi: 10.1016/j.nut.2016.02.001. Epub 2016 Mar 2.

Roasting intensity of naturally low-caffeine Laurina coffee modulates glucose metabolism and redox balance in humans.

Author information

1
Department of Medical, Surgical and Health Sciences, Clinica Medica AOUTS, University of Trieste, Trieste, Italy.
2
Institute for Kinesiology Research, Science and Research Center of Koper, University of Primorska, Koper, Slovenia.
3
Faculty of Health Sciences, University of Primorska, Izola, Slovenia.
4
illycaffè S.p.A., Trieste, Italy.
5
Department of Medical, Surgical and Health Sciences, Clinica Medica AOUTS, University of Trieste, Trieste, Italy. Electronic address: biolo@units.it.

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.

KEYWORDS:

Coffee; Insulin resistance; Omega-3 fatty acids; Oxidative stress; Roasting intensity; Type-2 diabetes mellitus

PMID:
27158053
DOI:
10.1016/j.nut.2016.02.001
[Indexed for MEDLINE]

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