We recruited several hundred women in their 50s and 60s and gave them all 500 mg of calcium a day, to at least prevent bone loss due to insufficent calcium.
They tend to excrete more calcium in the urine, and the vitamin D could make it worse.
We've suspected the link for a long time because sodium pulls calcium out in the urine.
Q: Would we need less calcium if we ate less protein?
A: Really high protein intakes will cost a little calcium, but I don't see that as a major contributor to calcium loss in most people.
Q: Should people who take a calcium supplement also take magnesium?