Only hyperforin-rich concentrates moved digoxin; tea and juice did not
Ten products were given with digoxin for fourteen days. Tea, juice, oil extract and low-dose powders changed nothing; the concentrates cut exposure by 18 to 27 percent.
What the study found
Tea, juice and oil extract left the heart drug digoxin alone
Ten St John's Wort products were given alongside digoxin for fourteen days. Tea, juice, oil extract, a hyperforin-free extract and the low-dose powders changed nothing measurable. Only the hyperforin-rich concentrates did, cutting digoxin exposure by 18 to 27 percent.
The caveat · About nine people in each arm
Ninety-six volunteers across eleven groups is about nine per arm, so a null in any one arm means no effect was detected at that size, not that none exists. Digoxin is handled almost entirely by the drug pump rather than by the liver enzyme, so these results speak to one half of the mechanism.