4 ms·
For me this was the most interesting tidbit: > In tests with mice, however, the animals did not seem to prefer drinking heavy water over regular water, althoug
by nicklecompte 6y ago
For me this was the most interesting tidbit:
> 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.
I was reminded that rodents also can’t taste aspartame[1], and that in general human taste buds are more finely-tuned than many other mammals (we can detect isomers and many complex bitter chemicals, whereas many other animals can only do the amino acids, sodium, and simple carbohydrates).
Having never drank it myself I was wondering if the sweet taste of heavy water is distinctly “artificial” in the way that sucralose/aspartame/etc in water is immediately distinguishable from regular sugar.
[1] https://www.nature.com/articles/nature726 https://www.nature.com/articles/nature726
- kazinator 6y agoWouldn't the olfactory bundle above your nose be a number of times larger than an entire rat's brain? Not to mention everything downstream of it ... A lot of the smell sensitivity comes from ("carefully tuned?") positive feedback loops int the olfactory systems which amplify small signals. Or something like that, supposedly. Not my area. At least, not the input side. On the output side of stink, I'm no theorist either; maker, for sure, though!
- nicklecompte 6y agoBut this is specifically not smell, or even about the brain: it’s about what chemicals the tastebuds are physically capable of detecting. In particular the sweet taste of heavy water seems to be purely related to the sweet taste buds (though there may be secondary flavors that come from the smell). Within humans there is considerable variance among bitter tastebuds. Roughly speaking, the salt/sour/sweet tastebuds are comparatively simple ion detectors: salt = sodium, sour = hydrogen (from the acid), and sweet = glucose. And yes, sweet is more complicated, because it’s trying to detect a more complicated form of aquatic solute. But the idea is that these tastes are trying to find a specific and well-defined chemical property. Bitterness is different. Bitterness is basically a poison detector, which means that to be effective it needs to register a wide variety of potential toxins. So akalais/bases tend to be bitter because naturally-occurring bases tend to be toxic. But there are all sorts of complex organic molecules that may be toxic (or are chemically very similar to toxins), which some people can taste and others cannot. Cilantro is probably the most famous example: people who hate cilantro are tasting a (harmless) toxin that other people can’t detect. But this taste is a true taste from the tastebuds, not a smell.
- dtgriscom 6y ago"harmless toxin" is an oxymoron...
- danielheath 6y ago"Toxin present at harmless concentrations" might be more to your tastes.
- deleted 6y ago[deleted]
- cratermoon 6y agoArguably the concentration of alcohol in many cocktails and beverage exceeds "harmless" levels.
- nicklecompte 6y agoI was being a bit pithy - the bitter tastebuds are giving a “false positive” and identifying something as poisonous when it isn’t (not to humans anyway - linalool, the major flavor oil in cilantro, is an insecticide, and not very healthy for many other mammal species). Possibly there is a dangerous chemical out there found in berries/leaves/etc which is structurally similar to linalool, enough to fool certain types of bitter tastebuds.
- eyegor 6y agoPersonally I can pick out ingredients and tasting notes better than most of my friends and I have almost no sense of smell. Although I think in general smell is supposed to dominate taste, blocking your nose when you eat has a strong effect on flavors or something. Doesn't affect me much.
- sfgweilr4f 6y agoI had a very similar takeaway. As a kid, I used to get stomach aches and a long list of other issues. Fast forward after a bunch of tests as an adult and the results reported to me by a doctor spelt out that most artificial sweeteners are effectively poison to me. If I want a headache, stomach ache, etc I just consume one of the many sweeteners out there. The "hyper-sweet" taste and after-taste I get from most artificial sweeteners for me is a signal of poison or bad food. Its a clear signal to avoid that food in future. My question is the same: I wonder if D2O would have that same kind of "twisted" sweetness? Secondary questions: I wonder if our ancestors did the same? Noticed that they didn't feel well and that was enough to tip the selection balance such that we now have the ability to detect D2O? How subtle would that effect be? or is just it tied into a specialised "anti-poison" set of structures we've got to detect bad-food? I think this is more likely. D2O is bad water. We have senses for other kinds of bad water as well.
- _nalply 6y agoI think, it's sort of a side effect. The ancestor's taste buds were optimized for giving them better chances of survival, and one feature was better detecting of sweetness. D2O didn't exist then and so couldn't influence survival, so detection of D2O is just an accident.
- elihu 6y agoHuh. So, when Reepicheep in Prince Caspian discovers that the ocean is no longer salty but tastes sweet, we can rule out that the oceans of the far reaches of the world containing Narnia are made of heavy water, because if it were then he wouldn't have been able to taste it. Though I suppose any fan theory in this direction could be salvaged by the conjecture that talking mice are different.
- Knufen 6y agoI work in a lab where we have plenty D2O, I will give it a try later and report back. Edit: The taste was definitely different but not enough so that I could say it wasn't placebo
- deleted 6y ago[deleted]
- rirze 6y agoHow was it stored? I find that containers also influence taste of water heavily.
- Knufen 6y agoWe use it for NMR experiments, so in a glass container and with extremely high purity. So no salt, minerals or anything else normal water contains.
- denton-scratch 6y agoWere you comparing your highly pure D20 with similarly pure H20?
- Knufen 6y agoUnfortunately we can't guarantee that the high purity H2O is bacteria free, so unfortunately not.