- For the purpose of this study, two acute randomized, controlled, cross-over human intervention trials were conducted.
- The effect of coffee intake, matched for caffeine but differing in CGA content (89, and 310 mg) on flow-mediated dilation (FMD) was evaluated in 15 healthy male subjects.
- In a second intervention trial conducted with 24 healthy male subjects, the effect of pure 5-caffeoylquinic acid (5-CQA), the main CGA in coffee (5-CQA; 450 mg and 900 mg) on FMD was also examined.
- Researchers observed a bi-phasic FMD response after low and high polyphenol, (89 mg and 310 mg CGA) intake, with increments at 1 (1.10 ± 0.43% and 1.34 ± 0.62%, respectively) and 5 (0.79% ± 0.32 and 1.52% ± 0.40, respectively) hours post coffee consumption.
- The results of this study showed that FMD responses to coffee intake was closely paralleled by the appearance of CGA metabolites in plasma, notably 3-, 4- and 5-CQA and ferulic-4'-O-sulfate at 1 h and isoferulic-4'-O-glucuronide and ferulic-4'-O-sulfate at 5 h.
- The findings demonstrated that intervention with purified 5-CQA (450 mg) also led to an improvement in FMD response relative to control (0.75 ± 1.31% at 1 h post intervention, p = 0.06) and concomitant appearance of plasma metabolites.