The problem is always the same, you can't patent it so nobody will pay for a trial to prove it works.
Experts emphasize that most people can meet their nutritional needs through a healthy diet
This is always repeated, but the fact is around 90% of people don't.
A solution to this was invented in the soviet union, phage therapy. The FDA doesn't like it because it doesn't fit their regulatory framework, and it's not profitable, so it's not used.