Do calcium supplements interfere with absorption?
Calcium interferes with iron absorption. So, if you’ve had a major hemorrhage and you’re trying to recover that blood loss by taking iron tablets, it would make good sense to separate your iron dose from your calcium supplements. Calcium has a very slight interference with certain antibiotics such as tetracycline, which is used to treat acne. It’s been shown that high doses of calcium can reduce the absorption of thyroid hormone. Again, it’s a small effect, maybe 10 percent or 20 percent less absorption. I’m sure there are a few other drugs that would fall under the same category, but nobody has reported any major effects. How does a low calcium intake result in lower bone mass? Because calcium is so abundant in the environment, the human physiology evolved without having to learn how to conserve calcium because you always were going to get plenty with your next day’s meal. And as a result, we don’t hang onto calcium very well. We leak it out in the urine and in sweat. It comes out in
