One preparation cut a test drug 21 percent, another 79 percent
Both are St John's Wort: fourteen days of a near-hyperforin-free powder against fourteen days of a hyperforin-rich extract. The constituent that decides which is on neither label.
What the study found
From a fifth to four fifths, depending which preparation you bought
Fourteen days of a near-hyperforin-free powder cut exposure to a standard test drug by 21 percent. Fourteen days of a hyperforin-rich extract cut it by 79 percent. Both are St John's Wort, and the constituent that decides which is which appears on neither label.
The caveat · Chosen to span the extremes
The six preparations were selected to span the hyperforin range, so the gap between them is wider than a random pair off a shelf would be. About seven men per arm. How far real products vary has been shown to be large but has never been given a number.
What we don't know
The six preparations were selected to span the hyperforin range, so the gap between them is wider than a random pair off a shelf would be. About seven men per arm. How far real products vary has been shown to be large but has never been given a number.