Abstract
This paper reports clinical studies on the effect of agonists of taste and chemethesis receptors in the oropharyngeal cavity and the gut. The peripheral nerve system plays a vital role in our selection or rejection of what we eat and drink. Although the degree to which it is hard-wired has not been determined, it is known that our food and drink choices change with age. Scientific studies on the impact of food and drink on the body have been concerned predominantly with nutritional factors and, more recently, impacts on cholesterol and blood sugar levels. On the other hand, the sensations we experience during eating and drinking have long been regarded, perhaps even dismissed, as purely hedonistic. The idea that foods and drinks may actually influence digestion is a novel one and is based on the discovery 20 years ago of taste buds, innervated by the vagi, in stomach and intestinal tissues. Studies indicate some of our most popular drinks modulate both postprandial hyperaemia and gastric emptying. It is proposed that the bitter taste experienced with some foods and drinks promotes increased blood flow to the splanchnic circulation and slows the flow of chyme to the small intestine. In cases of toxicity, these actions promote emesis whereas at non-toxic levels, bitter substances promote digestion by increasing postprandial hyperaemia and slowing gastric emptying. Additionally, chemethesis agonists can act on the oropharyngeal receptors resulting in a slower gastric emptying. These effects may lead to a learned behaviour and subsequent enjoyment of bitter tastants, rather than their rejection, amongst those with reduced digestive capacity. It provides a rationale for the popularity of certain bitter tasting aperitifs and digestive alcoholic beverages originating in southern Europe.