Researchers are warning that popular herbs and supplements, including St. John’s wort and even garlic and ginger, do not mix well with common heart drugs and can also be dangerous for patients taking statins, blood thinners and blood pressure medications. St. John’s wort raises blood pressure and heart rate, and garlic and ginger increase the risk of bleeding in patients on blood thinners, the researchers said. Even grapefruit juice can be risky, increasing the effects of calcium-channel blockers and statins, they said. “This is not new research, but there is a trend toward more and more use of these compounds,...