Background: Arterial wave reflections (WR) are determinants of cardiovascular performance and predictors of the corresponding risk. The aim of this study was to assess whether there is a differential effect of coffee and caffeine on WR and whether this effect is related to habitual coffee consumption.

Methods: We studied 24 healthy volunteers (11 habitual-13 nonhabitual coffee consumers) on 4 separate occasions receiving: (a) triple espresso, (b) decaffeinated triple espresso, (c) 240 mg of caffeine alone (amount contained in a triple espresso) and (d) placebo. Augmentation index (AIx) was measured as an index of WR using a validated system (Sphygmocor^®). Higher AIx values indicate increased WR and vice versa.

Results: The effect of coffee and caffeine on WR is described as response of each variable, where response is defined as net coffee or caffeine minus placebo values at each time point. In the whole population, coffee and caffeine increased AIx, however the effect of coffee was more pronounced (left figure). Habitual and nonhabitual drinkers demonstrated similar changes with caffeine, whereas the effect of coffee (regular: middle figure; or decaffeinated: right figure) was more potent in nonhabitual compared to habitual drinkers. Pressures also increased, however the increase was more potent in nonhabitual drinkers after both regular (p < 0.05) or decaffeinated (p < 0.01) coffee intake.

Conclusions: Both coffee and caffeine increase WR, however drinking coffee leads to a more potent response in nonhabitual drinkers. These findings indicate that substances other than caffeine are partially responsible for the unfavourable effects of coffee on the cardiovascular system.