For all you guys supplementing with l-tyrosine and whatnot, from Wikipedia:"A non-food source of phenylalanine is the artificial sweetener aspartame. This compound, sold under the trade names Equal and NutraSweet, is metabolized by the body into several chemical byproducts including phenylalanine."..."Phenylalanine uses the same active transport channel as tryptophan to cross the bloodbrain barrier, and, in large quantities, interferes with the production of serotonin."If you drink a lot of diet soda, you may not want to actually supplement with phenylalanine or l-tyrosine. Just an FYI.