Thanks to our taste buds, we can enjoy sweet treats such as the Shamrock Shake at McDonald’s when they hit our tongue. While we don’t notice it the same way, new research indicates that the heart can also “taste” sweet things.
This study – the first to make the “surprising” discovery of “sweet taste” receptors in the heart, per this press release – will be presented during the 69th Biophysical Society Annual Meeting, to be held February 15 - 19, 2025 in Los Angeles. Researchers found that the receptors are similar to the ones on the tongue and that stimulating them with sweet substances can modulate the heartbeat.
“While taste receptors are traditionally associated with the tongue and our ability to perceive flavors, recent studies have shown that these receptors exist in other parts of the body, where they likely play different roles,” said the press release from The Biophysical Society.
Around a decade ago, a research team from the University of Queensland in Australia found both smell and taste receptors in the human heart. At that time, they identified 12 taste receptors that mostly responded to bitter compounds.
Now, the new study has identified two specific receptors that respond to sweet things, the TAS1R2 and TAS1R receptors on the surface of heart muscle cells. Researchers stimulated the receptors in both human and mouse heart cells with aspartame, a common artificial sweetener, and observed a “significant increase in the force of heart muscle contraction and accelerated calcium handling.”
“After you eat a meal, it’s been shown that your heart rate and blood pressure actually are increasing,” Micah Yoder, a graduate student in the lab of Jonathan Kirk at Loyola University Chicago, explained. “Previously, this was thought to be a neural axis that’s being signaled. But we’re proposing a more direct consequence, where we have a spike in our blood sugar after eating a meal, and that’s binding to these sweet taste receptors on the heart muscle cells, causing a difference in the heartbeat.”
Both of the processes that increased when the heart’s sweet receptors were stimulated are important parts of a healthy heartbeat. Authors of the study hope that the observations can improve our understanding of heart function and potentially help develop new treatments for heart failure.
Another interesting finding from the study was that more sweet receptors were present on the hearts of patients who suffered from heart failure, “suggesting a possible link to disease,” according to the press release. Along with triggering increased force in heart muscle contractions and accelerated calcium handling, stimulating the sweet receptors in the heart also resulted in a “cascade of molecular events.”
“During heart failure, the heart is changing its energetic landscape and prioritizing glucose uptake and glucose usage,” said Yoder. “So, it’s possible that during this energetic change, the heart might need to change its nutrient sensing abilities to accommodate this switch.”
Yoder and his team also found a potential link between the consumption of artificially sweetened beverages and arrhythmogenesis, or an irregular heartbeat. They found that overstimulation of sweet taste receptors leads to an increase in arrhythmic like behavior in heart cells.
Currently, the U.S. Food and Drug Administration considers aspartame safe for consumption. As of last September, the FDA said that a person would have to consume more than 4,920 aspartame packets to exceed the safe daily limit, based on its sweetness intensity.
According to the press release about the new study, further research is needed to fully understand the long-term effects of stimulating the heart’s sweet receptors. It also said further research is needed to explore how “these receptors might be targeted to strengthen the heart in the case of heart failure.”