But what if there were a neuroprotective compound with better early-stage results than any developed pharmaceutical sitting right on our dinner plates?

That's what Dr. Paul Cox may have discovered after solving the mystery of neurodegenerative disease on Guam, where in the 1990s, the rates of ALS and Alzheimer's-like symptoms were 120% higher than in the rest of the world.

Dr. Cox would eventually discover that cyanobacteria, the same lifeforms that make green algae, produce a natural toxin called BMAA that was seeping into trees on the island. The trees would then grow seeds rich in the toxin—seeds that were eaten by flying fox bats, which in turn were hunted by locals for protein.

The BMAA was then poisoning the locals and causing, as Dr. Cox put it, deaths from neurodegenerative diseases in "every family" that he spoke to. In 2003, Cox told the world about it.

"When we realized that cyanobacteria might be the culprit, it was like staring into the abyss because we realized you could be exposed anywhere," Dr. Cox told CNN in a mini-doc, who didn't in any sense say that cyanobacteria was the cause of Alzheimer's, but that it was a "risk factor."

Seeking to understand and quantify the toxicology of BMAA, Dr. Cox ran a trial through his non-profit, the Brain Chemistry Labs at the Institute for Ethnomedicine, Jackson. What he discovered was that when monkeys were given the toxic BMAA plus an amino acid called L-serine, the neurotoxic effect was reduced by 85%.