Hi, I appreciate your service! I have osteopenia, and am looking for vitamin D3 (800) and calcium carbonate (12 mg) vitamins that my primary recommended. I m looking for a good deal, and find out that it s a huge industry out there. I almost considered by one Dr. Hans Nieper, but, thankfully, googled him, and found that he is actually pretty controversial with no research to back up some of his claims. So, my question is are there any brands that doctors & pharmacists ave recommended? And if not, do you have some guidelines for I can suss them out more quickly! (Too many choices, on a Friday night no less!)