Many people think that red algae, plant-based source for calcium and some other good things is better, more easily absorbed like what we get in food…so I tried AlgaeCal, very good and expensive…for me personally, I had to switch to a supplement with less magnesium, which can loosen stool, etc…so I joined ConsumerLabs and found one that’s organic, plant-based and 3rd party tested and has lower magnesium : New Chapter…..also, it comes in a version with smaller dosages, so you can adjust….there actually are a lot of such supplements, so it can be confusing…as always, i check in with docs first. Wish you all good luck, because this does require individual research.