This whole idea of aspartame becoming methanol is bunk. Sure, it happens, but in such small amounts. According to http://www.finchcms.edu/cms/biochem.../aspartame.html , a normal can of diet soda has 0.024g of methanol produced in the body. Tens or hundreds of grams are necessary to approach lethal or problematic dose. That might be an issue if you're drinking over 50 sodas a day, but I doubt even the heftiest of soda drinkers are doing that.