Nope. Not even close.
So what do you have to do to poison yourself with heavy water? To show the initial effects, you'd have to drink about a quarter of your water weight. Those initial effects in mammals are sterility - D2O in high enough concentrations is toxic to rapidly dividing cells, just like radiation or free-radical generating chemical species; this is a result of the altered kinetics when free protons begin to be replaced with slightly-more-than-twice as massive deterium nuclei. Consequently as the concentration increases, the damage begins to effect other high-turnover tissues next, like the GI tract and after that, presumably the central nervous system. Mammals given only heavy water die after a week. It turns out a disgruntled employee at a Canadian nuclear power plant spiked the office water cooler with D2O back in 1990, but it wasn't enough to replace any significant water weight as mentioned above, and no one was injured.
One interesting (but simplistic) idea was that in slowing the reaction kinetics of an organism's biochemistry, you could slow the organism's aging. And indeed it was shown that Drosophila given D2O did live longer. No telling what's going on to their gametes or nervous systems, or what would go on in a longer-lived more neurologically complex organism!
The question of why our ancestors made some very basic chemical commitments (nerves based on sodium, potassium and calcium flux, for example) is interesting but ultimately not useful, very likely having to do with the happenstance of what was available and soluble at the Earth's wet crust. Lithium is similar enough to sodium that it can fool certain sodium channels in the central nervous system and decrease the rate or amplitude of mood swings in bipolar people, but that's a coincidence.
By the way, the werewolf formulas are pretty disappointing. There was one where you can use a mixture of nightshade and children's blood and smear it on your skin during a full moon but it didn't work. Maybe you can't use your own blood like I did (but I was ten, so it should count.) Another way is to drink water out of a wolf paw print in the Harz Mountains in Germany. I'll have to import the wolves since they're not extirpated in Germany.