Biologically speaking, there's no risk to drinking DI water over any other kind of fresh water.
a) The difference in concentration of ions between tap water and DI water is practically non-existent compared to the concentration difference between drinking water and the fluids in our cells and blood. Yes, injecting pure DI water into your blood will lead to cytolysis, but so will injecting regular tap water. Our stomach and intestinal cells have spent hundreds of millions of years adapting to fresh water, DI water won't phase them one bit
b) DI water can't possibly strip you of anything. Strip it how? First, your stomach is a specific kind of two way street, digestive enzymes and acid out, nutrients and water in (unless you have an ulcer). Our food all has wildly different concentrations of ions and minerals, some lower than what's in our blood and some higher. Not only is there no mechanism in for that to lead to nutrients bleeding out in to your stomach when you eat or drink something with a low concentration of a particular ion, there's actually all sorts of systems in place to force the uptake of certain nutrients against a concentration gradient.
c) even if somehow the DI water was able to get ions or minerals to dissolve out of your blood back in to your stomach, it would all get re-absorbed in it's day long trip through your intestines.
d) The instant you swallow a glass of DI water, it stops being DI water. It mixes with your saliva first, then the juices in your stomach. By the time that water reaches your kidneys no one in the molecular jungle could tell the difference between water that came from a DI solution, or regular top water. We have a very elaborate system of organs and membranes whose sole job it is to maintain appropriate ion concentrations in the right places. Assuming you also eat (and I promise you, no one in N. America is lacking salt in their diet), the absence of ions in DI water is completely irrelevant to that process. I refer to point A: once the water hits your stomach the difference between tap and DI water disappears.
e) we (industrialized nations) don't get a significant portion of any ion or mineral from the water we drink on a day to day basis, regardless of what kind of water that is. That all comes from our food, and in most cases we get it in gross excess (mmmmm salty french fries). Not getting any calcium or magnesium or salt or nitrogen or what have you in DI water will neither somehow force you to lose those substances (refer to points about kidneys, organs and membranes), nor will it be missed if you ever also eat.
f) there's only one kind of fresh water poisoning, it's called hyper-hydrosis. drinking DI water will only do it to you if you drink say 10 gallons of it in an hour. But then, drinking 10 gallons of tap water in an hour will also do it to you. It will happen if you drink more water than your kidneys can possibly eliminate really quickly, causing the concentration gradients between your cells and your blood to get out of whack enough to become dangerous. That requires a near compulsive consumption of water, and will happen if you drink any kind of water that is hypotonic to your blood in high enough quantities (which is all potable water)
Commercially produced DI water is considered unfit for human consumption because of the industrial resins they use to produce it. It's not intended for human consumption so there's no safety testing in place to guarantee that the myriad of strong acid and strong base cation and anion resins producing any one batch aren't leaving poisonous chemicals in the water or leaving it dangerously acidic or basic. This might also be true for the kinds of resins we use, but if that's true, it's a danger from the resin, not the absence of ions in the water.
aaaaand, I'm getting off my soap box
