[atombender]

The Candida link is interesting but not proven — so in that sense it's equivalent to your cancer guy.

The other discoveries predate a lot of advanced medical technology, though. They were the low-hanging fruit in that sense. The only semi-recent discovery I can think of is that the Epstein-Barr virus causes cancer, though that does not necessarily qualify as "simple". EBV is also implicated in MS. EBV could ultimately be one of those "unifiers" that could explain multiple diseases.