If beryllium, a pale, hard-to-melt metal sitting at #4 in the periodic table, were to land on your tongue in a taste test, you’d suspect sugar, but don’t try this at home! Beryllium will never be a sugar substitute in our diets since even minute doses are extremely toxic.  Exposure to beryllium can scar the lungs and produce a nasty chemical pneumonitis.  As Sam Kean writes in The Disappearing Spoon, “when it comes to the periodic table, it’s best to keep our mouths shut.”