Around 2011-2014, a coworker told me about a fellow online who was claiming that he'd solved all the world's health problems by narrowing the cause down to peoples' bodies having an acidic pH level instead of alkaline. The history of alkaline water pseudoscience goes back much farther,[1] but that was the earliest I heard of it in 21st century America. There was a list of "alkaline" vs. "acidic" foods, etc.

It was very much in the same vein as the "aspartame is POISON!!!" chain emails of the 1990s, so I was disappointed when I started to see products on store shelves catering to the belief.

I'm not seeing any obvious hits for the original source now, unfortunately. Maybe someone else has traced its modern incarnation back even further.

[1] https://ua.pressbooks.pub/pseudoscienceessays/chapter/the-al...

The alkaline food trend comes at least in part from a quack who called himself "Dr. Sebi".

Google is saying it's used for weight loss via the high ph levels.