So this is just crazy, and Donald Trump readers can stop reading now, since they don't believe elites or science, but everyone else, this is cool.
You can read the entire article here - but the key take away is that scientist thought UV light might slow down MS, since there is less MS in the tropics than at the northern altitudes.
In running a test with control groups, they found that sunscreen actually held the key ingredients. It was what they expected and had to retest, but in true scientific method they ran a test and control groups (UV with Sunscreen, UV without Sunscreen, Sunscreen without UV and control group with neither). They found two active ingredients - homosalate and octisalate - particularly strong in Coppertone, are effective in slowly the advance of MS.
It is a great side effect of doing scientific investigation correctly. Again - Donald Trump readers who don't believe in science are free to ignore this.