Does Heavy Water Taste Sweet?

November 3, 2021

Ordinary pure water doesn’t have a definite taste, but what about heavy water? Does it taste sweet, as anecdotal evidence dating back to the 1930s may indicate? And if so, why, if D2O is chemically almost identical to H2O, of which it is a stable natural isotope? These questions arose shortly after heavy water was isolated nearly 100 years ago, but until now they have not received a satisfactory answer. Now, researchers Pavel Jungwirth and Phil Mason, together with students Carmelo Tempra and Víctor Cruces Chamorro, from the Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences (IOCB Prague), together with Masha Niv’s group, from the University Hebrew, and Maik Behrens, from the Technical University of Munich,

In their research paper, published in  Communications Biology , they conclusively demonstrate that, unlike ordinary water, heavy water tastes sweet to humans, but not to mice, and that this effect is receptor-mediated. sweet taste human.

Heavy water (D2O) differs from normal water (H2O) only by an HD isotopic substitution and as such should not be chemically distinct. Leaving aside a trivial 10% change in density due to the double mass of D compared to H, the differences in the properties of D2O versus H2O, such as pH or melting and boiling points, are really very small.

These differences are due solely to nuclear quantum effects, that is, to changes in the vibrations of the zero point, which lead to a slightly stronger hydrogen bond in D2O than in H2O.

‘Even though the two isotopes are nominally chemically identical, we have shown conclusively that humans can distinguish by taste (which is based on chemical detection) between H2O and D2O, having the latter has a distinctly sweet taste ”, commented Pavel Jungwirth on the main result of his study. In their work, the authors complement taste experiments in human subjects with tests in mice and in HEK 293T cells transfected with the human sweet taste receptor TAS1R2 / TAS1R3, and with molecular modeling.

The results consistently suggest that the sweet taste of heavy water is mediated in humans by the TAS1R2 / TAS1R3 receptor. Future studies should be able to elucidate the precise sites and mechanisms of action, as well as the reason why D2O activates TAS1R2 / TAS1R3 in particular, resulting in a sweet taste (but not another).

Although obviously not a practical sweetener, heavy water allows a glimpse of the vast chemical space of sweet molecules. Since heavy water has been used in medical procedures, the finding that it can elicit responses from the sweet taste receptor, which is found not only on the tongue but also in other tissues of the human body, represents important information for clinicians and practitioners. your patients.

Furthermore, due to the wide application of D2O in the determination of chemical structures, chemists will benefit from knowing the present observations.

Finally, it is worth mentioning that 86 years ago,  Science published a short letter from HC Urey, (Nobel laureate for the discovery of deuterium) in which it was authoritatively stated that D2O is not distinguished from H2O by taste, which it had a strong, if misleading, effect on the current debate on the subject.

“Our study thus resolves an old controversy regarding the sweet taste of heavy water using state-of-the-art computer modeling and experimental approaches, demonstrating that a small nuclear quantum effect can have a pronounced influence on such a basic biological function as taste recognition.” , concludes Pavel Jungwirth.

Dr. Loony Davis5
 | Website

Born and raised in Brussels in an English family, I have always lived in a multicultural environment. After several work experiences in marketing and communication, I came to Smart Water Magazine, which I describe as the most exciting challenge of my career.
I am a person with great restlessness and curiosity to learn, discover what I do not know, as well as reinvent myself daily, someone who is curious about life and wants to know. I enjoy sharing knowledge.
This is my personal project but I also collaborate in other blogs, it is the case, the most important web on water currently exists in the US, if you are interested you can read my articles here.

Leave a Reply

Your email address will not be published. Required fields are marked *