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Science

Human Taste Buds Can Tell the Difference Between Normal and 'Heavy' Water, Study Finds (sciencealert.com) 104

An anonymous reader quotes a report from ScienceAlert: [T]here's been a longstanding question over whether heavy water tastes the same as regular drinking water -- or whether its subtle isotopic variation yields a different taste that people may be able to perceive. "There is anecdotal evidence from the 1930s that the taste of pure D2O is distinct from the neutral one of pure H2O, being described mostly as 'sweet,'" an international team of researchers led by first authors and biochemists Natalie Ben Abu and Philip E. Mason explains in a new study. [I]n their new research, Ben Abu, Mason, and their team can finally confirm that there really is something a bit different about the taste of heavy water. "Despite the fact that the two isotopes are nominally chemically identical, we have shown conclusively that humans can distinguish by taste (which is based on chemical sensing) between H2O and D2O, with the latter having a distinct sweet taste," explains senior author and physical chemist Pavel Jungwirth from the Czech Academy of Sciences.

In a taste-testing experiment with 28 participants, most people were able to distinguish between H2O and D2O, and tests with mixed amounts of the waters revealed that greater proportions of heavy water were perceived as tasting sweeter. In tests with mice, however, the animals did not seem to prefer drinking heavy water over regular water, although they did show a preference for sugared water -- suggesting that in mice, D2O does not elicit the same sweet taste that people can perceive. Other taste tests conducted by the team suggest why this is so, indicating that human taste receptivity to D2O is mediated by the taste receptor TAS1R2/TAS1R3, which is known to respond to sweetness in both natural sugars and artificial sweeteners. Experiments in the lab with HEK 293 cells confirmed the same thing, showing robust responses in TAS1R2/TAS1R3 expressing cells when exposed to D2O.
The findings are published in the journal Communications Biology.
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Human Taste Buds Can Tell the Difference Between Normal and 'Heavy' Water, Study Finds

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  • Duh (Score:5, Funny)

    by theshowmecanuck ( 703852 ) on Monday April 12, 2021 @10:37PM (#61267046) Journal
    That's why it makes better ice cubes for evening cocktails. That subtle hint of deuterium.
    • by Kunedog ( 1033226 ) on Monday April 12, 2021 @11:43PM (#61267176)
      Hijacking top comment to link the Thunderf00t (Philip E. Mason) video:

      https://www.youtube.com/watch?... [youtube.com]

      It's 43 minutes but worth it if you like well-presented details of science experiments and concepts.
    • Re:Duh (Score:4, Funny)

      by boudie2 ( 1134233 ) on Tuesday April 13, 2021 @12:32AM (#61267226)
      Next week - Lead Paint, Delicious But Deadly. Hats off to Troy McClure.
      • The following week: Tide pods, the delicacy chosen en masse by the American youth.
        Great with Netflix, great at ball game and a school snack favorite.
        New flavors and enticing colors in the store near you!
        Chase it down with a windex-colored 64 fl oz sugar bomb from the gas station nearby!
        Who knew these colors could give your kid such fine taste bud sensation?!

      • McClure is great and all, but I've heard some disturbing rumors about him and fish.
      • Try lead acetate instead, once used as a sweetener: https://en.wikipedia.org/wiki/... [wikipedia.org]
    • by dohzer ( 867770 )

      Just like when my ice cubes acquire a slight hint of last night's casserole from the leftovers in the freezer. Yum!

    • Re:Duh (Score:5, Interesting)

      by ShanghaiBill ( 739463 ) on Tuesday April 13, 2021 @01:45AM (#61267312)

      A few years ago, I bought 20 ml of D2O on eBay and gave it to my daughter as a Christmas present.

      We had fun making ice cubes that sink.

      But we also tasted a few drops. It definitely has a sweet taste.

      Another cool trick is to wet your finger with D2O and then touch a normal H2O ice cube. The D2O has a higher freezing temperature so it will immediately solidify and latch your finger onto the ice cube.

      There are YouTube videos of other stuff you can do with heavy water. Great for an afternoon of quality father-daughter time ... assuming, of course, that she inherited your nerd gene. The next year, I gave her 100 grams of gallium.

      • Great for an afternoon of quality father-daughter time ... assuming, of course, that she inherited your nerd gene. The next year, I gave her 100 grams of gallium.

        Very nice! Thanks for some great ideas. D2O might not be available here, might raise more questions. I hope I can get hold of some of that gallium here.

        • by pjt33 ( 739471 )

          There's a YouTube channel called Cody's Lab which has some videos about home manufacture of heavy water. (I suspect it's mainly DOH rather than D2O, but it's a long time since I watched the videos).

          • Not only does he distill and taste heavy water (he indeed confirms that it is sweeter):
            https://www.youtube.com/watch?v=MXHVqId0MQc

            But he also purchases some heavy oxygen water (_quite_ a bit more expensive!) and tastes that as well:
            https://www.youtube.com/watch?v=KH46r9Fvla4
        • Re:Duh (Score:5, Interesting)

          by ShanghaiBill ( 739463 ) on Tuesday April 13, 2021 @03:29AM (#61267496)

          D2O might not be available here, might raise more questions. I hope I can get hold of some of that gallium here.

          Where do you live? I got both from eBay. Most sellers will ship worldwide.

          I also bought some metallic sodium for my son. It is soft enough to cut with a butter knife. So we sliced off a chunk and tossed it into a bottle of water, and tried to capture the resulting hydrogen in a balloon. Unfortunately, the sputtering sodium ignited the hydrogen, the balloon exploded, and the liquid sprayed out. We were wearing eye protection but still got some lye burns on our forearms.

          The pain helped with the male bonding.

          • Yeah, metallic sodium and water aren't good friends. There's some pretty awesome videos of sodium metal being dropped into bodies of water. It's not what I'd deem an efficient means of producing hydrogen.

          • by dfm3 ( 830843 )
            If you want to capture hydrogen at home, try magnesium (you can pick up a chunk sold as a fire starting block anywhere that sells camping supplies) and vinegar. The reaction is slower, safer, less exothermic, and produces magnesium acetate which is much less harmful than caustic sodium hydroxide.
      • Interesting that you could taste the difference, for me it was just rather expensive water, didn't taste any different from standard distilled water. Mind you I probably have cast-iron taste buds...
      • by dentin ( 2175 )

        That's awesome, and a really great idea of something to do with your kids.

        I tasted some heavy water ~30 years ago, and I remember very specifically that 1) it definitely tasted different, and 2) it seemed sweet. It seems strange that it would take so long for a paper to be written about the topic.

      • The best source of heavy water is United Nuclear [unitednuclear.com]. If you just want a taste 10 mL for $15 should suffice. If you are in to ice cube experiments and demos, then 100 mL for $90 might be better.

        I have an element collection and have two vials with a short piece of polystyrene rod in light water, and heavy water. Polystyrene has a density of 1.05, half way between light and heavy water.

        BTW - don't bother with trying to make heavy water at home. Even the simplest approach takes a considerable investment of effort

        • I absolutely love this concept and will be buying some.

          For those who may be as confused as I was:

          1. D2O is evidently sold by weight, not by volume. $15 buys 10 grams, not 10 millilitres.

          2. 100g of D2O is only about 60ml, or about 1/4 US cup (~4 tablespoons). So $15 would only get you 6ml, or less than half a tablespoon.

          3. United Nuclear might have better quality control, but 1000g (~1 imperial pint / 1.25 US pints) costs $725.00, and the same weight can be purchased on eBay for $500.

          4. There are currently

    • Plus, I like ice cubes that sink. No frozen lip ptoblem.

  • by iggymanz ( 596061 ) on Monday April 12, 2021 @10:38PM (#61267048)

    Claims of "chemically identical" are ignorant nonsense, no chemist would say that. Chemistry of things dissolved in heavy water is different, some biological reactions or slowed or don't happen at all. If 25 percent of the water in your body were replaced you'd become sterile and cell division would slow down, your ability to heal or grow new tissue would be hampered. Increasing your body's concentration to 50 percent heavy water would kill you.

    • If 25 percent of the water in your body were replaced you'd become sterile and cell division would slow down

      So what you are saying is, as far as drinking water is concerned, Deuterium is the new Fluoride!

      • One tenth percent heavy water would do nothing to you, one tenth percent fluoride water however...

        • Well, one tenth percent of salt ...

          • Re: (Score:3, Insightful)

            by iggymanz ( 596061 )

            your kidneys could handle a glass of water of that concentration of table salt, whereas the stuff added to water by cities but in that concentration would kill you. Hilarious in this century the allowed amount of flouration of water halved because the dose they were giving the populace turned out to be very close to the dose that would damage bones... truth is plenty of european countries have better teeth health and no fluoridation of water, but we keep adding this poison. It's not needed, there are smar

            • by Anonymous Coward
              Umm, no. The amount originally recommended was a few magnitudes lower than the lower limit of fluoridation that even hinted of something in the most rare possible interactions. The target fluoridation was halved because nearly everyone these days uses fluorinated toothpaste and having fewer chemicals in the water is better. And actually, most places in the USA have to remove naturally occurring fluorine. This means that in most cases, the reduced recommended levels will actually result in more natural fluor
              • absolutely false and ignorant. The former concentration cities were using went as high as 4 mg per liter, and could push young children into the danger range, even to weakening bones.

                -- from Reuters, January 7 2011

                The EPA did a risk-assessment study on whether some children may now get too much fluoride.

                The study concluded that some children under the age of 8 may be overexposed to fluoride at least occasionally because of their high fluid intake compared to their body weight or because of high natural lev

                • the new limit is 0.7 mg / liter by the way.

                  Zero need for it, smarter ways to protect teeth and Europe doing superior job without flouridating water. No need for this poison in our water.

        • by Anonymous Coward

          It would do nothing 'noticeable' to you.

          It will almost certainly impede something somewhere inside of you.

          Interestingly, I did read in a journal somewhere that tests between D2O and H2O resulted in fewer errors when DNA is copied. You still don't want to be drinking any amount of the stuff, though.

    • by msauve ( 701917 )
      >If 25 percent of the water in your body were replaced you'd become sterile and cell division would slow down

      You mean I didn't have to pay for that vasectomy, and wouldn't have to worry as much about being overweight? Why didn't you say so earlier? I predict a new market for D2O, replacing the current alkaline water fad.
      • Except you would be poisoned; cell division brought to halt (spindle apparatus can't function), enzymes stopping working... you'd be dead in about a week if experiments with small mammals any indication.

    • by sjames ( 1099 )

      The claim probably comes from the simplified way isotopes are defined for K-12 students. It's mostly true, but isotopes of hydrogen are a big outlier due to the huge difference in atomic mass between hydrogen and deuterium.

    • Anyone curious will enjoy a deep dive into this. It's still hydrogen and water, but if I remember right the bond angle is different and there's an interesting story about why.

      That in turn makes differences that matter a lot in biology.

      • by Grantbridge ( 1377621 ) on Tuesday April 13, 2021 @05:45AM (#61267684)

        The main difference is the chemical energy to break the bond, as the zero-point vibrational energy is different.

        Basically when you have two atoms bound together, there is a minimum vibrational energy they can have, due to the way the quantum mechanics works out. Deuterium being heavier than Hydrogen has a lower minimum energy, and so the bond is harder to break than a normal H-O bond, as it starts from a lower energy level.

    • To work anything out in chemistry it's a necessity to work with massively simplified models of underlying reality. Of course, different isotopes are not identical, but for many problems the differences are as good as rounding errors and therefore ignored. If the differences are not accounted for in your model of chemistry - you say they are chemically identical. It's a perfectly valid way to look at things, conditional on the type of problem you are working on.
      • by Grantbridge ( 1377621 ) on Tuesday April 13, 2021 @05:47AM (#61267686)

        The fact chemists give Deuterium a different letter, D rather than H, gives you a hint they consider it to behave differently. C12 and C13 don't get different letters, they get a superscript instead.

        Since the only difference is their weight, it only really matters for H. He doesn't really do any interesting chemistry it doesn't get it's own letter for different isotopes like H does.

        • by paiute ( 550198 )

          The fact chemists give Deuterium a different letter, D rather than H, gives you a hint they consider it to behave differently. C12 and C13 don't get different letters, they get a superscript instead.

          Since the only difference is their weight, it only really matters for H. He doesn't really do any interesting chemistry it doesn't get it's own letter for different isotopes like H does.

          Chemists do use superscripts to denote the different hydrogens (imagine the numbers are superscripted): 1H for hydrogen, 2H for deuterium, 3H for tritium. We use the shorthand H, D, and T because we can. There is no equivalent short name for 12C, 13C, and 14C, so we have to use the superscripted designations.

          The behavior of an isotope has nothing to do with how we represent it in a formula - that is specified in the IUPAC naming conventions/rules.

          Helium does have isotopic forms and are designated in th

          • The reason behind the use of the different letters is their different chemical behaviour though. You use D often enough it would be a pain to write H^2 every time. When you are buying deuterated NNR solvent, or writing H/D solvent exchange mechanisms, it's simply easier to use D rather than H^2. If other isotopes were used as commonly, they would have developed their own additional letter code!

            • by paiute ( 550198 )

              The reason behind the use of the different letters is their different chemical behaviour though. You use D often enough it would be a pain to write H^2 every time. When you are buying deuterated NNR solvent, or writing H/D solvent exchange mechanisms, it's simply easier to use D rather than H^2. If other isotopes were used as commonly, they would have developed their own additional letter code!

              True but misleading. As someone who made his living for many years synthesizing compounds labeled with 2H and 3H and 12C and 14C, I would have used a shorthand for the carbon isotopes, but there are none. It is just a historical oddity that 2H and 3H ended up with trivial names.

      • Not a rounding error in the case of heavy water. The point is that hydrogen bonding strength so very important to biology especially enzymes and spindle apparatus for cell division the difference is massive, reactions don't happen or rate are dramatically slowed. No competent chemist/biochemist is going to claim heavy water identical to water.

    • by habig ( 12787 )
      I wonder if the difference in binding to taste receptors might not be related to the fact that as a molecule that's 1/9th heavier than ordinary H2O, the D2O's thermal velocity is thus slower, giving it a better chance to interact with whatever signals "sweet taste" to your tongue: simply because it's moving more slowly and thus has a better chance to react before bouncing away.
  • by BigBlockMopar ( 191202 ) on Monday April 12, 2021 @10:41PM (#61267054) Homepage

    There we go. Heavy water, the ultimate in pricey bottled water.

    Move over, Perrier. This one's got kick!

    It's neat that we can taste the difference, and if bottled water suppliers can mass produce it as a beverage it will surely reduce the operating costs of some types of nuclear reactors.

    • by sjames ( 1099 ) on Monday April 12, 2021 @11:13PM (#61267126) Homepage Journal

      Plus we get to remove the genes that drive people to buy designer water from the gene pool! Big WIN!

    • by piojo ( 995934 )

      There we go. Heavy water, the ultimate in pricey bottled water.

      Move over, Perrier. This one's got kick!

      You should try heavy oxygen water. It costs several times more!

    • Once again, Hogan’s Heroes was ahead of its time.

      https://www.imdb.com/title/tt0... [imdb.com]

      • Funny enough, Wilson Tucker wrote The Time Masters wherein human looking aliens needed heavy water so as to live thousands of years, and since they were shipwrecked on Earth the few of them that survived sought out the German's stockpile during WWII. But time moved on, some looked to America for a new supply, and one desperate alien had "a cunning plan", lol. It first came out in 1953, but I read the revised edition of 1971 that a SF book club had as a featured monthly release. Ah, my personal golden age of
      • by bws111 ( 1216812 )

        Ashamed to admit that is the first thing I thought of when I read the headline.

      • Yup, first thing that popped in my head. "Can I die from it? "Only if Berlin finds out"
    • Perrier got nothing on gold-flake-"flavored" thick vitamin water "with real diamonds".

    • by sfcat ( 872532 )

      It's neat that we can taste the difference, and if bottled water suppliers can mass produce it as a beverage it will surely reduce the operating costs of some types of nuclear reactors.

      Not the kind we want though. Heavy water moderation has two advantages, you can use natural uranium instead of LEU and it makes more Pu. Neither of these are really an advantage these days though. LEU is very cheap and making Pu is problematic unless you are making weapons.

    • by narcc ( 412956 )

      If it catches on, we'll certainly have bottles labeled heavy water...

    • Fukushima just has 1.5l of superheavy water left that they want to get rid of....

  • Looking forward to their followup paper on whether tritium water is even sweeter.
  • don't "confirm" anything. I mean, if there's already been enough past exploratory data to suggest a hypothesis, why would you bother with a 28 participant study?
    • Not sure of your point. If a one person study was able to prove one person could tell the difference then that would confirm it. Adding more people doesn't really alter the binary nature of the question "can a human detect the difference via taste beween H20/D20". Are you suggesting they need more than 28 people for some reason? You'd only need that if, say, the one person you tested wasn't able to. If >0 of the 28 people were able to then that confirms it - no more people needed.
      • by Anonymous Coward

        You really don't have a firm grasp of this whole "science" thing, do you?

        • Maybe you can enlighten me then. I want to determine if a human's taste buds can tell D2O from H2O. I find 28 people, and sure enough at least a few of them can reliably, in double blind tests, tell the difference.

          Now, since you're a real scientist maybe you can explain to me how I haven't proved that they can do so? And how, apparently, I need a larger trial of say 10000 people? Good luck getting that funding.

    • That's OK. Since I have less than 28 people with me to read your comment in a double-blind study, and it hasn't been peer-reviewed, it doesn't exist.

  • tastes like spherical chickens

  • by rossdee ( 243626 ) on Tuesday April 13, 2021 @12:06AM (#61267204)

    How does slightly heavy water taste?
    Also known as Deuterium Hydroxide.

    Apparently invented by Homer Simpson, at Montgomery Burns nuclear facility.

    DOH

  • by swell ( 195815 ) <jabberwock@poetic.com> on Tuesday April 13, 2021 @12:32AM (#61267228)

    People I know have no discrimination in their taste of water.

    Our tap water is awful and many people in my city will agree. But then many will buy a brand of bottled water that is nearly as bad. My preference is distilled water which for me has an exciting 'electric' taste. Unfortunately I've cracked some ribs and need some 'dirty' water with minerals at least some of the time. There is another brand of bottled water locally that tastes much like distilled water, but it is not a big seller. People just can't tell the difference! I've tried water from big impressive filtration systems and it's good, but inconvenient and expensive. So now I use a Zero filter at home for very pure water. Yum.

    I'm also mystified by the popularity of Starbucks and similar coffee. It's terrible! I suppose the kids tolerate it because it is filled with sugar and candy like ingredients. How would they know what the actual coffee tastes like? So I'm a bit suspicious of a 'scientific' study that claims people can distinguish a subtle taste difference. It must be a major difference, and that sweetness sounds really creepy to me.

    • by amorsen ( 7485 )

      Bottled water tastes of bottle. Unless it is in a glass bottle, but then it is usually San Pellegrino. Funnily enough, San Pellegrino's horrible taste overpowers any container it might be in, so it is a mystery why they like to use glass bottles.

    • Distilled water is bitter. Can only stand it in a tea.

      • by Twinbee ( 767046 )
        Not all distilled water is equal. Check the TDS levels for one. It may not be as pure as you think. Even with very low TDS, I tried some distilled water from one brand, and it tasted like plastic. From another brand, it tasted great.
        • Not all distilled water is equal. Check the TDS levels for one. It may not be as pure as you think. Even with very low TDS, I tried some distilled water from one brand, and it tasted like plastic. From another brand, it tasted great.

          It also depends on which solids are dissolved in it.

    • I'm also mystified by the popularity of Starbucks and similar coffee. It's terrible!

      You are absolutely right. Starbucks tried to make inroads in Switzerland, using their standard US-style brewed coffee. Horrible stuff - just like standard coffee in nearly all US restaurants is horrible. They had to give in and buy decent coffee machines here, just to bring themselves to the same standard as every other coffee shop in the country, but at twice the price.

      Their (few) branches here stay in business for two reasons: (a) the sugary drinks they sell, and (b) they have comfortable furniture, so

      • by pjt33 ( 739471 )

        Here in Spain the few branches I've seen seem to survive on tourists and American students.

    • Check the label carefully, most major brands of bottled water are just tap water sourced from a municipal supply and "enhanced with minerals" (their wording!) to mask the flavor. To me, this often makes them taste "soapy" and slightly brackish.

      Instead, go for a bottle labeled as "spring water" and you'll find that it's usually more local brands from local sources - wells or capped springs - and minimally processed. And it has the trace elements in it naturally. Most of the smaller brands of spring water ar
      • Water that's too pure tastes funny because it lacks minerals.

      • Hell, in Hot Springs National Park (Arkansas), the spring water is free - but you have to bring your own container. The National Parks Service maintains a bunch of public distribution points. Most are hot - quite hot - and thus completely untreated. Some are naturally cool and are IIRC ozonated for antibacterial function.
      • We used distilled water in our kid’s brand new vaporizer for the same reason, but then it didn’t work. No vapor at all, even though it’s clearly on. Come to find out, there’s a section in the instructions for how much salt to dump in the water if you aren’t seeing it do anything, since it apparently requires minerals in the water to help conduct the current. Sure enough, a few pinches of salt later and the thing worked fine.

        I suspect it’d have worked mostly fine after a f

    • by Twinbee ( 767046 )
      Just add something like the product "40000 Volts" to distilled which restores minerals to the water, without the crud that goes along otherwise.

      Btw, not all distilled water is equal. Some taste like plastic, and the other one I had tasted just like a decent bottled water, nothing really special, just a nice 'nothing' taste.
    • I've found the AquaHydrate water is rather delicious, you might like to try it out.

  • be the next artificial sweetener?

  • I need more proof, maybe contaminant in the heavy water caused it? Who knows?
    Would like multiple independent studies and spectrographic analysis of the water.

    • by Luckyo ( 1726890 )

      Read the study. It pre-empts your complaints. In fact in the video about how they made the water, they specifically state that they did it to counter pedantic people who would complain about it. They literally distilled water in a specially sealed container tubes which had to be created for each batch of water and then tossed to ensure no contaminants after end product was extracted.

  • I hope they tested with pure water. And didn't overlook that there might be minerals in the H2O, or stuff (like helper chemicals) from making D2O in that.

    I don't have time to read the study. So if anyone read it...?

    • by swilver ( 617741 )

      Good thing we have you to think about these things, these researchers probably never thought of that.

  • Alien (but human looking) taste buds sure could, lol. Anyone else remember that novel from their personal "golden age of science fiction"?
  • Sweetness is something we seek out because there is an evolutionary advantage to consuming sugars. Does heavy water taste sweet because there is some benefit to drinking it, or is it a toxic coincidence like lead acetate?
    • Probably not, but that won't stop hucksters from selling it as a miracle cure, weight-loss and sleep aid!

      • You'd need to be careful. A liter of heavy water a few times a week would probably not cause an issue, but if someone got stupid about it and started drinking *nothing* but heavy water, it would kill them in a few weeks: wiki link [wikipedia.org] - we don't worry about toxicity in humans right now because no one is getting their hands on enough heavy water to significantly displace normal water in their system, but if this caught on as a fad like alkaline water someone will be dumb enough to exclusively drink it and die.
    • Does heavy water taste sweet because there is some benefit to drinking it ...?

      Likely not. Some things in nature happen due to an accidental "misfiring." A classic case is why flying insects swarm to an artificial light source at night. They evolved over millions of years with the moon as the only light source at night. Since the moon is so far away, flying around doesn't change its position relative to you, so you can still fly in a straight line, so it's reasonable to navigate by it. Flying insects are h

    • In large enough quantities is disrupts cellular function and leads to death. I suspect it's coincidentally sweet like lead acetate or ethylene glycol (that one is a bugger and kills a few kids and pets every year) - but kind of like lead acetate and ethylene glycol you're unlikely to encounter significant sources of it in nature so evolution never filtered it out of our taste buds.
    • Sweetness is something we seek out because there is an evolutionary advantage to consuming sugars. Does heavy water taste sweet because there is some benefit to drinking it, or is it a toxic coincidence like lead acetate?

      If you read the article, drinking too much can cause infertility and / or death.

  • Sweetened with heavy water!
  • Next, let's chug a glass of H2O and H2O2! Will that extra molecule of oxygen create a cleaner, more refreshing taste?

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