I also would like to know the safe dosage
God knew what He was doing when He made food, and added vitamins in very, very small doses.
True - but those God-made foods aren't available in the super markets - even if they have an 'organic' section without all the chemicals, pesticides etc....as they've all been out of the ground for days to weeks...and every day they are out of the ground, their vitamin-mineral levels drop.
I get my eggs and vegetables delivered to my door, free delivery, from a farmer 2 miles down the road. I take a a 20 mile trip to a farm for my 'grass fed' beef. I get organic fat back to render my own NON-hydrogenated lard. I make ghee from organic butter. I grow what vegetables I can in summer.
You want God-foods, don't go to the super markets.