By Cullen’s time the bitters were acknowledged as a particular group of plants with specific actions. Cullen lectured on their capacities under both bitters and tonics, and he divides the bitters into hot and cold, amara calida and amara frigida, wormwood, of course counting among the calida. Bitters are seldom simple, he says, but combined with other qualities. More recently Schulz et al (1998) differentiate simple, aromatic, astringent and acrid types. ‘Proper tonics are bitters’ Cullen says. His appraisal both encompasses the applications we have met through the tradition above, other uses from the past to be covered below, and anticipate our modern conception of their bitter actions. On the common qualities he discusses, he offers his own experience, which does not always corroborate the general claim. The ‘common qualities’ include:
1. action on the stomach; increasing appetite for food and promoting digestion of it, the improvement depending upon an increase in tone of the muscular fibres, hence ‘restoring tone to that organ’; correcting acidity and flatulence, checking fermentation, and relieving the stomach from abundant mucus or phlegm. This improved state, communicated to other parts of the system improve the tone of the whole
3. diuretic, possibly directly so but there may be other mechanisms, he estimates
4. for intermittent fevers, through their tonic power in the stomach
5. for continued fevers, although their effect is ambiguous
6. sudorific, although only with a sudorific regimen
8. emmenagogue, not perceived so by Cullen
9. resolving coagulations produced by falls and contusions, again unestablished by Cullen
10. anthelmintic (discussed later).
This list is followed by two external uses: for cleansing and healing foul ulcers Cullen found bitters useful, and universally employed in fomentations for discussing tumours. Here Cullen is more doubtful of their efficacy. He covers also the use of bitters for gout but has reservations on their long-term use, which may result in apoplexy.
Grieve recommends wormwood as a good remedy for enfeebled digestion and debility. A light infusion of the fresh tops is excellent for all disorders of the stomach and helps promote appetite and digestion, and prevent sickness after meals, but she cautions that if too much is taken it will produce the contrary effect. Grieve includes too a recipe from Dr John Hill of 1772: 1 oz of flowers and buds in an earthen vessel, iy2 pints of boiling water poured on and left to stand all night. The following morning the clear liquid is taken with 2 spoonfuls of wine at three draughts iy2 hour’s distance from each other; ‘whoever will do this regularly for a week will have no sickness after meals, will feel none of that fullness so frequent from indigestion, and wind will be no more troublesome; if afterwards, he will take but a 4th part of this each day, the benefit will be lasting’.
In herbal medicine today bitters form a mainstay of practice. The human taste receptor that responds to a variety of bitter compounds has been identified. Schulz et al (1998) record how the stimuli in the mouth by reflex induce gastric and biliary secretions, arguably only where they are below optimal level, and their reflex action on the cardio-vascular system, decreasing heart rate and cardiac stroke volume. Mills (1991) offers full expression of their use. Unlike Cullen, he designates them ‘cold’, yet he expresses the paradoxical temperament of wormwood, one of the bitterest plants, but its acrid constituents ‘raise its temperature’. Mills records how the broad applications of the bitters stem from their many capacities, as they:
1. increase appetite
2. increase digestive secretions, hence not only improvement of digestion but less likelihood of enteric infections, and not necessarily a contraindication in hyperacidity
3. protect gut tissues since sphincter tone is increased, mucosal regeneration promoted and enhanced recovery from pancreatic disease
4. promote bile flow, hence good liver function
5. enhance pancreatic function, thus possibly useful in late onset diabetes mellitus with a normalizing of pancreatic hormone secretion
6. act as a tonic, promoting good health.
The uses documented by Mills recall a number of familiar applications from tradition and add new ones: he lists their use for biliary disorders, including gall bladder disease and some instances of high cholesterol, liver conditions, loss of appetite, reactive hypoglycaemia, chronic inflammatory diseases of the skin, joints, vascular system, bowels, migraines and fevers. Schulz et al (1998) emphasize the psychological component of appetite, citing a trial in which bitters improved appetite in people with gastric achylia, despite their inability to produce stomach acid. The bitter taste too is necessary. The same range of effects cannot be achieved if this is bypassed by using, for example, coated pills.