Thank you for your reply, and heavens no, I’m not suggesting reducing calcium.
Rather, I suspect that the RDA for vitamin D is too low, perhaps by an order of magnitude. If our skin can produce 10,000 IU of D with just half an hour of strong sunlight, then I don’t believe larger (1000 to 5000 IU) of supplementation advised by some vitamin D researchers could be toxic. One of the (few) reasons given for not taking larger doses of D is that calcium levels in the body can get too high, leading to problems like kidney stones. However, other researchers point out that this condition only develops if calcium supplements are taken along with the larger dose of vitamin D. I was only referring to taking a calcium supplement in the context of taking large amounts of D, not the 10 or 20 ug/day used in the study. My suspicion is that in the study, 400 to 800 IU of D may be too low to show solid benefits, unless aided by a calcium supplement.
I recall my dad had a bad bout of kidney stones, at a younger age than I am now. Before beginning a vitamin D supplement, I did some research into possible side effects. I’ll avoid a calcium supplement, my usual dietary intake (I like dairy) should be sufficient.
The only other supplement I take is fish oil, and there is some interesting synergy (to me,anyway) in how the body uses omega 3 and vitamin D, not necessarily calcium. The US has just begun a five-year study of both omega 3 and vitamin D supplements, with 20,000 people, but I’m not waiting for the results, I’m trying it on my own.
That was in the findings of the first linked study of postmenopausal women. But the particulars of the thing are too far beyond me. One thing I noticed in that study is that they supplemented with calcium carbonate. The claim has been that the calcium in calcium citrate is much more absorbed than the calcium in calcium carbonate.
So, does that have anything to do with developing kidney stones? I have no idea. I post these articles for whom they may help and leave them to their own research.