Heavy water differs from regular water in that the hydrogen atoms that make up the proton and the electron in it replace the stable isotope of hydrogen – deuterium. Deuterium also contains a neutron in its nucleus. Thus the density of heavy water is 10 percent higher than that of normal water. Chemically, both types of water are nearly the same, indicating that they have the same taste, i.e. neutral.
“Despite the fact that these two isotopes of water are chemically identical, and although the perception of taste depends on chemical properties, we clearly showed that humans, unlike mice, are able to distinguish their own tastes.” Said the team leader, physicochemist Pavel Jongworth, who works at IOCB, “Heavy water tastes sweet to us.”
Scientist recently on the Academy of Sciences podcast Science at your fingertips He said that the first scientific evidence of the sweet taste of heavy water appeared in the interwar period. However, a short article by a Nobel Prize winner in chemistry on the discovery of deuterium was also published by Harold C. Urey in the mid-1930s, claiming that the two waters were tasteless. And it was this outcome that greatly influenced the debate about the taste of heavy water for a long time.
The current team has experimented with humans and mice, as well as genetically modified cells that contain human sweet taste receptors. According to Jungwirth’s previous statement, this eliminated the potential psychological aspects that could affect people even in the case of blind experiences. Then the scientists combined these methods with molecular modeling methods. And they found that the taste of heavy water in humans is mediated by the future of sweet taste.
“This proves that there is a weak but real effect in the perception of the sweet taste of heavy water, which occurs directly at the level of the taste receptor, and not elsewhere in the signaling pathways. In fact, this means that it is through our language that we can perceive the differences caused by the quantum effects, which is Wonderful, ”Jongworth emphasized. According to him, this old scientific dispute over studies is fading.
The attempt began with curiosity
The scientist said he and his colleagues first tasted heavy water in about five years. However, the standard experiment began at a later time. “We met with a colleague in Israel who is testing artificial sweeteners and he has about twenty students. It took about two years,” the scientist said of the length of the research.
Heavy water is also used, for example, in medicine – in measurements of metabolism. According to IOCB representatives, knowing that it triggers a reaction to sweet-taste receptors, found on the tongue and in other body tissues, could be useful information for clinicians and patients.
More studies should find out the exact location and way in which heavy water activates taste receptors in humans so that it tastes sweet. Jungwirth indicated that he would like to participate in this research as well. “But we’ve encountered such a wall there now – we don’t know exactly what the sweet-taste receptor structure looks like. So we’re waiting to see if there is any crystallography, or cryo-electron microscope, defining the structure. Then we can ask where exactly this effect appears.”
“Most importantly, we know that the receptors behave differently in heavy water and in light water. But in heavy water, the receptors of the salty or bitter taste also behave differently. The question is why is it sweet, and why it is not salty or bitter. We cannot answer this question. Today. So I think we still want to move there, ”Jongworth concluded.
On behalf of the IOCB, Jungwirth worked on the research with Phil Mason and students Carmelo Tempre and Victor Cruces Chamorre. A group led by Masha Neff from the Hebrew University in Jerusalem and Mike Berns from the Technical University of Munich also participated in the project.