title: Bitter tastants alter gastric-phase postprandial haemodynamics.
abstract: BACKGROUND
  Since Greco-Roman times bitter tastants have been used in Europe to treat digestive disorders, yet no pharmacological mechanism has been identified which can account for this practice. This study investigates whether the bitter tastants, gentian root (Gentian lutea L.) and wormwood herb (Artemisia absinthium L.), stimulate cephalic and/or gut receptors to alter postprandial haemodynamics during the gastric-phase of digestion.
  
  
  METHODS
  Normal participants ingested (1) 100 mL water plus capsules containing either cellulose (placebo-control) or 1000 mg of each tastant (n=14); or (2) 100mL of water flavoured with 500 or 1500 mg of each tastant (a) gentian (n=12) and (b) wormwood (n=12). A single beat-to-beat cardiovascular recording was obtained for the entire session. Pre/post-ingestion contrasts with the control were analysed for (1) the encapsulated tastants, in the "10 to 15" minute post-ingestion period, and (2) the flavoured water in the "5 to 10" minute post-ingestion period.
  
  
  RESULTS
  Water, the placebo-control, increased cardiac contraction force and blood pressure notwithstanding heart rate decreases. Encapsulated tastants did not further alter postprandial haemodynamics. In contrast gentian (500 and 1500 mg) and wormwood (1500 mg) flavoured water elicited increased peripheral vascular resistance and decreased cardiac output, primarily by reducing stroke volume rather than heart rate.
  
  
  CONCLUSIONS
  Drinking 100mL water elicits a pressor effect during the gastric-phase of digestion due to increased cardiac contraction force. The addition of bitter tastants to water elicits an additional and parallel pressor effect due to increased peripheral vascular resistance; yet the extent of the post-prandial blood pressure increases are unchanged, presumably due to baroreflex buffering. The vascular response elicited by bitter tastants can be categorised as a sympathetically-mediated cephalic-phase response. A possible mechanism by which bitter tastants could positively influence digestion is altering gastric-phase postprandial haemodynamics and supporting postprandial hyperaemia.
authors.affiliation: Division of Complementary Medicine, University of Westminster, London, UK. Electronic address: research@micmcmullen.se.
authors.forename: Michael K
authors.initials: MK
authors.lastname: McMullen
authors.affiliation: Division of Complementary Medicine, University of Westminster, London, UK.
authors.forename: Julie M
authors.initials: JM
authors.lastname: Whitehouse
authors.affiliation: Naturally Scientific, Nottingham, UK.
authors.forename: Peter A
authors.initials: PA
authors.lastname: Whitton
authors.affiliation: Department of Psychology, University of Westminster, Westminster, UK.
authors.forename: Anthony
authors.initials: A
authors.lastname: Towell
mesh_terms: D000328:Adult; D031171:Artemisia absinthium / Q000737:chemistry*; D001794:Blood Pressure / Q000187:drug effects; D004063:Digestion / Q000187:drug effects*; D005260:Female; D005753:Gastric Mucosa / Q000378:metabolism; D030012:Gentiana / Q000737:chemistry*; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D008875:Middle Aged; D018517:Plant Roots / Q000737:chemistry*; D019518:Postprandial Period; D013270:Stomach / Q000187:drug effects*; D013649:Taste / Q000187:drug effects / Q000502:physiology*; D055815:Young Adult
keywords: Artemisia absinthium; Bitter tastants; Cephalic response; Gentiana lutea; Postprandial haemodynamics; Postprandial hyperaemia