Ya, that is what I was thinking - it would take a heck of a lot to overdose.
50,000 units is what Wiki says, NIH said 40,000 was about the limit.
So how much was Null getting? They must have really overloaded those supplements.
HINT - if you take supplements regularly, it might be a good idea to leave a day or two each week without any supplements so the body can adjust to overloads.