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Carbohydrates, glycemic index and diabetes mellitus

Effect of cocoa and green tea on biomarkers of glucose regulation, oxidative stress, inflammation and hemostasis in obese adults at risk for insulin resistance



Flavanols may provide protection against insulin resistance, but little is known about the amounts and types of flavanols that may be efficacious.


This study was designed to determine whether cocoa flavanols, over a range of intakes, improve biomarkers of glucose regulation, inflammation and hemostasis in obese adults at risk for insulin resistance. As an adjunct, green tea and cocoa flavanols were compared for their ability to modulate these biomarkers. In a randomized crossover design, 20 adults consumed a controlled diet for 5 days along with four cocoa beverages containing 30–900 mg flavanol per day, or tea matched to a cocoa beverage for monomeric flavanol content.


Cocoa beverages produced no significant changes in glucose, insulin, total area under the concentration–time curve (AUC) for glucose or total insulin AUC. As the dose of cocoa flavanols increased, total 8-isoprostane concentrations were lowered (linear contrast, P=0.02), as were C-reactive protein (CRP) concentrations (linear contrast, P=0.01). The relationship between cocoa flavanol levels and interleukin-6 (IL-6) concentrations was quadratic, suggesting that a maximum effective dose was achieved (quadratic contrast, P=0.01). There were no significant effects on measured indices of glucose regulation, nor on those of total 8-isoprostane, CRP and IL-6 concentrations, when cocoa and green tea were compared. However, relative to cocoa, green tea lowered fibrinogen concentrations (P=0.0003).


Short-term intake of cocoa and green tea flavanols does not appear to improve glucose metabolism; they do affect selected markers of one or more measures of oxidative stress, inflammation or hemostasis in obese adults at risk for insulin resistance.

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We thank Mars Incorporated for providing the cocoa treatment beverages. We also thank Dr Catherine Kwik-Uribe for providing flavanol analysis of the cocoa treatment beverages and thoughtful manuscript review. This study was supported by the US Department of Agriculture.

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Correspondence to K S Stote.

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Stote, K., Clevidence, B., Novotny, J. et al. Effect of cocoa and green tea on biomarkers of glucose regulation, oxidative stress, inflammation and hemostasis in obese adults at risk for insulin resistance. Eur J Clin Nutr 66, 1153–1159 (2012).

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  • cocoa
  • green tea
  • polyphenols
  • insulin resistance
  • obesity

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