Plain, clear water does not taste distinctive, but what about heavy water – does it taste sweet, as anecdotal evidence dating back to the 1930s indicates? And if yes – why, when D2O is a practically chemically identical to H2O, which is a stable isotope that occurs naturally? These questions arose shortly after heavy water was isolated nearly 100 years ago, but have yet to be satisfactorily answered. Now, researchers Pavel Youngferth and Phil Mason with students Carmelo Tempra and Victor Cruces Chamorro at the Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences (IOCB Prague), together with the Masha Niv group at the Hebrew University and Mike Berns in Munich Technical University found answers to these questions using Simulation of molecular dynamics, cell-based experiments, mouse models, and human subjects. In their research article published in Communication BiologyThey conclusively showed that, unlike regular water, heavy water tastes sweet to humans but not to mice, with this effect being mediated by the human sweet-taste future.
Heavy water (D2O) differs from regular water (H2O) by replacing only the HD isotopes, and as such, it should not be chemically different. Leaving aside a trivial 10% change in density due to doubling of the mass of D compared to H, the differences in properties of D2O versus H2O, such as pH or melting and boiling points, are indeed very small. These differences are only due to nuclear quantum effects, that is, changes in zero-point vibrations, which lead to a slightly stronger hydrogen bonding in D2O compared to H2O.
“Despite the fact that the two isotopes are chemically identical, we have conclusively shown that humans can distinguish by taste (which depends on chemical sensing) between H2O and D2O, even though the latter has a distinct sweet taste,” Pavel Jongworth commented on the main finding of their study . In their work, the authors complement human taste experiments with tests in mice and HEK 293T cells transported with the human sweet taste receptor TAS1R2 / TAS1R3, and with molecular models. The results consistently point to the fact that the sweet taste of heavy water is mediated by TAS1R2 / TAS1R3 receptors in humans. Future studies should be able to elucidate the exact sites and mechanisms of action, as well as why D2O activates TAS1R2 / TAS1R3 in particular, resulting in a sweet (but not another) taste.
Although it is clearly not a practical sweetener, heavy water offers a glimpse of the chemical space that is wide open to sweet molecules. Since heavy water is used in medical procedures, the discovery that it can trigger sweet-taste receptor responses, which are not only found on the tongue but also in other tissues of the human body, are important information for clinicians and their patients. Moreover, given the wide application of D2O in determining chemical composition, chemists would benefit from being aware of current observations.
Finally, it is worth noting that 86 years ago, Science He published a short message from HC Urey, Nobel Prize winner for the discovery of deuterium (HC Urey & G. Science81, 273, 1935. http: // doi.
“Our study thus resolves an ancient controversy regarding the sweet taste of heavy water using the latest experimental methods and computer models, which indicates that the effect of a small nuclear quantum can have a clear effect on a basic biological function such as taste recognition,” Pavel Jungworth concludes.
Original paper: sweet taste of heavy water. Natalie Bin Abu, Philip E. Mason, Haad Klein, Nitzan Dubowski, Yaron Bin Shushan-Galitsky, Enav Malach, Veronica Brynkova, Linka Malitenska, Carmelo Tempra, Victor Cruces Chamorro, Joseph Kvashka, Mike Burns, Masha Young Neversh. Communication Biology 2021.https: /
Professor Pavel Gongworth, DSc. (Born 1966, Prague) is a Czech physical chemist, educator, and science activist. He studied physics in Prague at Charles University, Faculty of Mathematics and Physics, where he majored in Chemical Physics. He did his doctorate work in computational chemistry at the J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences under the direction of Professor R. Zahradník. He spent several years abroad as a postdoctoral professor and later as a visiting professor, primarily at the University of California, Irvine, the University of Southern California in Los Angeles, and the Hebrew University in Jerusalem.
Currently, Pavel Jungwirth heads a research team at the Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences (https: /
Pavel Jungwirth has published over 300 original research papers in international journals, including ScienceAnd Nature Chemistry, And PNAS, With over 15,000 quotes. He is executive editor of the Journal of Physical Chemistry published by the American Chemical Society. He is also President of the Association of Learners in the Czech Republic, and has received numerous awards, among them the Spiers Memorial Prize of the British Royal Society of Chemistry, the Jaroslaw Herovsky Honorary Medal for Merit in Chemical Sciences from the Czech Academy of Sciences and the Humboldt Research Prize. Pavel Jungferth’s contributions to popular science appear regularly on the pages of the weekly Respekt magazine, and he is a frequent guest on Czech radio and television.
Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences / IOCB Prague (https: /