Sugar in soft drinks and other processed foods may be bad for us, but cheating our taste buds has proved difficult — and the substitutes we do have (like the coal derivative found in Sweet'n Low) can sound even worse. A more "natural" solution is sweetener derived from plants like stevia, which has made its way into the recently launched Coca-Cola Life and other beverages. But as Daniel Engber writes in The New York Times, stevia's bitter aftertaste can easily turn a diet soda sour. Over the past several years, food scientists have struggled to make this raw material more palatable, but is a heavily processed version of a plant extract really any more natural than a synthesized chemical? And is "natural" a meaningful benchmark to try to reach?