Well, there's an older study of just postmenopausal women. The results are in the Feb. 16, 2006 edition of The New England Journal of Medicine. Data from that study was included in the results of this study reported in the British Medical Journal. I'm seeing dosages of more than just 400 IU of vitamin D.
Many experts in this area of research advise up to 5000 IU daily, to avoid deficiency. At this purported optimum vitamin D dosage, the body’s usage of calcium is optimized, too, so a calcium supplement should not be needed. I’d be wary of taking calcium along with high vitamin D supplements.
You may be right about amounts of calcium but you do need calcium for it to be used. That taking more vitamin D should dictate limiting calcium intake is something I would dispute. If vitamin D optimizes calcium usage then what is the best amount of calcium to take should be independent of the amount of vitamin D.
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.