dont know anything about MS and aspartame but for a healthy person there is absolutely no problem with consuming aspartame!
https://www.ncbi.nlm.nih.gov/pubmed/28938797
12 fl oz cola light (355 ml) contains 188 mg aspartame. so 1l cola light contains 530 mg aspartam.
ADI:
europe = 40mg/kg,
USA = 50mg/kg.
so a 90KG person’s ADI would be 3600mg.
if we compare this with the amount of coke, we see, that we can drink 6,8l coke light - every day and the whole life!
because this is, what the ADI tells us. the amount, an adult can consume daily and its whole life without any issues.
IF you would consume more than the 6.8l coke light, what would that mean to our bodies?
NOTHING. because the ADI is 1/100 of the NOAEL (NOAL is the value, where there wont be any negative effects - guaranteed no negative effects!)
EDIT: its absolutely proven that aspartame is not toxic in any way! its completely, 100% safe! everybody that tells you something different, ignores the existing evidence!