Bitter taste induces nausea

14 other feelings such as queasiness, weakness and gastric churning (see the Supplemental Information for details). GMA is modulated by activity from pacemaker areas of the stomach. Normal GMA oscillates at 3 cycles per minute (cpm). During either physical illness or sensations of nausea, the pattern shifts and dysrhythmias (bradygastria, 1–2.5 cpm, and tachygastria, 3.75–10 cpm) increase. Fast Fourier transform of the EGG signal enables the experimenter to determine the onset of nausea via shifts in the frequencies of GMA (see Figure 1E for power analyses) [8]. We asked 63 healthy subjects (fasted for four hours) to sample an intensely bitter, but non-toxic, solution (0.8 mM sucrose octa-acetate, SOA). The SOA solution was held in the mouth for three minutes and then expectorated. Overall, 20% of the subjects reported being strongly nauseated (MNP score > 45) by oral exposure to the bitter stimulus, 45% were mild to moderately nauseated (MNP score 45 to 15), and 35% did not experience any nausea or discomfort (MNP score < 15) (Figure 1A). MNP scores provided by the subjects were not correlated with their perceived bitterness intensity (r 2 = 0.06; Figure 1B), nor to their unpleasantness ratings of the solution (also r 2 = 0.06; data not shown). Almost all the subjects rated the SOA solution as being very bitter and very unpleasant. Why some people report nausea and others do not to the same nauseogenic stimulus is unknown, but such diversity of nausea responses is ubiquitous. Studies demonstrate there is a genetic component to nausea susceptibility. In addition, anxiety, conditioning, adaptation and tendency to report bodily changes also may underlie individual differences in nausea susceptibility (see [9] for review). To determine whether the induced nausea was specific to SOA, we tested a different group of subjects (n = 12) with both SOA and a second bitter intensity-matched solution of quinine hydrochloride (also 0.8 mM), a natural alkaloid that is commonly employed as a bitter tasting stimulus. The same proportions of subjects as in the previous study reported being nauseated by SOA and quinine solutions (Figure 1C). Moreover, the nausea ratings in response to SOA and quinine were Nausea is the most characteristic negative experience that typically accompanies toxin-induced illness. Because most plant-derived toxins taste bitter, there is a rational link between bitter tasting compounds in the mouth and nausea that often results from their ingestion. It is surprising then that there are …