I have seriously lowered my calcium intake since going low vitamin A. I used to need about 2000mg a day but after starting detoxing from(I had a medically diagnosed hypervitaminosis A for you who are not onboard with the general low A) it I suddenly neither craved or tolerated any supplemental calcium and now average about 200mg. It has made me worried it's too low but my nails and teeth have improved and my serum calcium has been normal and my PTH has been too. Saw a world wide calcium average by nation list and its interesting that nepal and uganda have an average daily intake of less than 150mg ca! I belive too little can be bad but seems it has a lot to do with context. I now Peat favoured high magnesium, low calcium in the beginning of his writing and then changed his views about in the 90'sI started taking Coral Ca/Mg which I thinks it does work, better than Calcium citrate.
Definitely the whole thing with PTH is puzzling. My PTH has been always low. I speculate it is due to high vitamin A, which I think does negatively affect calcium.