Last year, when my internist found out that my bone density had not been responding to the bisphosphonate I was taking, she changed my prescription and also strongly suggested that I begin taking Ultimate Bone Support because it has strontium in it. Being the compliant patient that I am, I ordered an entire year's worth of it. Since then, I have been taking it twice a day. In about a month, I will have another bone density test and will see whether or not this has been of help.