As it turns out, it’s not only the tongue that can taste. While previous research has focused on the heart’s bitter taste receptors, a new study has found that the human heart has taste receptors which can detect sweet taste
Furthermore, stimulating these taste receptors with sweet foods can modulate the heartbeat, according to the study presented at the Biophysical Society Annual Meeting in Los Angeles this month.
These sweet taste receptors, known as TAS1R2 and TAS1R3, can be found on the surface of heart muscle cells.
How does sweetness affect the heart?
Using the sweetener aspartame on the hearts of both humans and mice, the researchers found that it increased the force of heart contractions, as well as improved calcium handling. Both these contribute positively to heart health.
The increase in blood pressure and heart rate following a meal was previously thought to be linked to a neural axis, explains researcher Micah Yoder. However, it could be that it’s actually linked to the heart’s sweet taste receptors.
The research could explain why people with high consumption of artificial sweeteners often have an irregular heartbeat. Overstimulation of these taste receptors, he suggests, can lead to arrhythmic like (similar to irregular) behaviour in the heart cells.
So, are sweeteners good or bad for heart health?
It's complicated. While the research suggests that aspartame can improve the strength of heart contractions and calcium handling, both elements of a healthy heartbeat, sweeteners in large quantities can also cause one to develop an arrhythmic, or irregular, heartbeat.
It was also found that these taste receptors are significantly more prominent in those with heart failure.
According to the research, triggering the receptors sets off a series of molecular events within heart cells, which involve proteins that control muscle contraction and calcium flow.
The heart, explains Yoder, prioritises glucose usage and glucose uptake during heart failure, so, he speculates, it may change its nutrient-sensing abilities to accommodate this switch.
A bitter heart
Before the present findings on sweet taste receptors, existing research has focused on the heart’s bitter receptors.
In the tongue, these bitter taste receptors, or T2R’s, play the role of warning us about ingesting harmful substances. In the heart, however, research is still ongoing as to what they may actually be for.
Some research suggests that they may, much like the sweet taste receptors, affect how the heart contracts and pumps blood. Another potential impact may be on vascular tone, which is how constricted a blood vessel is.
Indeed, some studies on mouse hearts have shown that the heartbeat has been weakened by around 40% in response to bitter taste compounds, with these compounds also raising blood pressure.
Food containing bitter tastes, such as caffeine, may potentially have such an effect on the heart, modulating calcium signalling (a critical process in the heart that regulates its contractions). Bitter compounds in many foods could potentially have a significant impact on T2R’s.
T2R’s are found not only on the heart but the brain, gut, and lungs.
Sourced From: Frontiers
‘A Bitter Taste in Your Heart’
Published on: 8 May 2020
Doi: https://doi.org/10.3389/fphys.2020.00431
Authors: C. J. Bloxham, S. R. Foster, W. G. Thomas