Japanese daily intake is about 13 mg, I've seen one MD recommend that amount per day, its probably safe. He said that for liability purposes, it would be hard to be sued for prescribing a person the amount that a whole country basically ingests daily. 25 mg once a week was only my personal "gut feel". Here's a decent video, if you don't have time for the whole thing, skip ahead to about the 28 minute mark, and just put 5 minutes into it: https://www.youtube.com/watch?v=0GzvXfsnSTQ