Bitters: Time for a New Paradigm

In plant-based medical systems, bitter tasting plants play a key role in managing dyspepsia. Yet when
it comes to defining their mechanism of activity, herbalists and pharmacologists are split between two
theories: One involves cephalic elicited vagal responses while the other comprises purely local
responses. Recent studies indicate that bitters elicit a range of cephalic responses which alter
postprandial gastric phase haemodynamics. Caffeine and regular coffee (Coffea arabica semen L.)
increase heart rate whereas gentian (Gentiana lutea radix, L.) and wormwood (Artemisia absinthium
herba L.) increase tonus in the vascular resistance vessels. Following meals increased cardiac activity
acts to support postprandial hyperaemia and maintain systemic blood pressure. The increased
vascular tonus acts in parallel with the increased cardiac activity and in normal adults this additional
pressor effect results in a reduced cardiac workload. The vascular response is a sympathetic reflex,
evident after 5 minutes and dose dependent. Thus gentian and wormwood elicit cephalic responses
which facilitate rather than stimulate digestive activity when postprandial hyperaemia is inadequate.
Encapsulated caffeine elicits cardiovascular responses indicating that gastrointestinal bitter receptors
are functionally active in humans. However, neither encapsulated gentian nor wormwood elicited
cardiovascular responses during the gastric phase. These findings provide the platform for a new
evidence-based paradigm.