Is it true that airlines won't let pilots drink diet soda? I watched a documentary called Hungry for Change that claimed pilot associations advise avoiding diet soda due to the aspartame sweetener inhibiting motor skills and killing brain cells.

Is this true?
I've never gotten anything to this effect from my airline nor pilot union, and they'd better start stocking cans of unsweetened Snapple if they were to push this, because I don't like coffee &amp; I most certainly don't want to be drinking lots of sugary sodas to get my caffeine fix in the morning!