Is there any substance to the claim that taking magnesium supplements can improve blood pressure, anxiety, and act as a muscle relaxant? also is it safe ? im worried it will drop my heart rate very low

Magnesium: With certain health problems, e.g. severe kidney disease, magnesium balance can be important to monitor and treat. Also, certain rare and serious problems in pregnancy require IV magnesium treatment. But there is absolutely no proved health need for magnesium supplements. They probably aren't harmful in the doses some reccommend, e.g. health food stores, vitamin producers. No help but no harm.