Which type of magnesium is best as cardiac supplement??

Unclear: Studies still being done and literature argues back and forth to benefit. However little downside in person with healthy kidneys, so am for it. Mag-citrate is used to induce bowel movements (rapidly), so not best choice. Mag-sulfate less common now with Mag-Oxide as option. One capsule once or twice daily is usual dose if no deficiency & usually well tolerated. If get problem diarrhea, reduce dose