A dose‐response effect from cocoa consumption on biomarkers of oxidative stress and inflammation in adults at risk for insulin resistance

Abstract

This study investigated if there was a dose‐response effect of cocoa flavanols on biomarkers of oxidative stress and inflammation in adults at risk for insulin resistance. The study then compared the effect of the high dose cocoa and green tea on these outcomes. As part of a randomized crossover design, 20 obese subjects consumed a controlled diet with 5 treatments: 1) high dose cocoa (900 mg/d of flavanols), 2) medium dose cocoa (400 mg/d of flavanols), 3) low dose cocoa (200 mg/d of flavanols), 4) control cocoa (22 mg/d of flavanols), and 5) green tea (catechins matched for high dose cocoa). For five days, the treatments were consumed with breakfast and dinner. On the sixth day, after a 12 h fast, subjects consumed a 75 g glucose solution. Biomarkers (8‐isoprostanes, CRP, IL‐6, ICAM and fibrinogen) were measured during a 2 h period. Results showed that as the cocoa dose increased, 8‐isoprostanes decreased (p=0.02) with the medium dose having the maximal lowering effect. CRP decreased (p=0.01) as the cocoa dose increased. IL‐6 was lowered (p=0.0001) by the medium dose cocoa. Cocoa did not significantly affect ICAM and fibrinogen. When the high dose cocoa was compared to the green tea, the green tea lowered fibrinogen (p=0.0003) but no significant effects were observed on 8‐isoprostanes, CRP, IL‐6, and ICAM. Cocoa flavanol consumption of 400 mg/d or above may improve some important biomarkers of oxidative stress and inflammation.