I have been using high dose strontium for osteoporosis prevention for some time. There were several double blind studies with doses from 170-680 mg per day for 2 to five years. There was significant increase in bone density from 16-49 % compared to placebo with this high dose.
Studies and research now is questioning whether the does needs to be that high. We do know that it is higher than from the strontium we get in our diets. There have been cases of strontium sensitivity and at least one death from strontium. In Europe, strontium ranelate is a prescription medication for osteoporosis.
There is one study that shows a low dose can increase bone mineral density. There was a significant difference in those taking 170 mg strontium versus high dose.
We need more studies on this. I will be more conservative in the future until more research is done.