Aspartame, also known as NutraSweet, is an artificial flavor that is used as a substitute for sugar in diet sodas and some other drinks. It was discovered by chemist James M. Schlatter working for GD Searle and Company in the 1960s. When the Food and Drug Administration director refused to allow aspartame to be used in drinks, then President Ronald Reagan fired him and replaced him with Arthur Hull Hayes, who decided to allow aspartame to be used for drinks. Aspartame has been criticized by some nutrition experts for allegedly being linked to stomach ulcers and headaches, this has been disputed, however.