Standardized Extracts: What Do the Numbers Mean?

The percentages on a St. John's Wort label tell you how much of the active compound it contains. Understanding them is the key to choosing a product that works.

Why standardization matters

Standardization is what guarantees a product actually contains the ingredient it advertises, in an amount large enough to have an effect. By concentrating specific plant compounds to a set level, manufacturers can amplify the known benefits — and researchers can run trials whose results are dependable and reproducible.

Standardization is the best guarantee that a product contains what it's supposed to contain in amounts sufficient to produce a desired effect. — Dr. Andrew Weil, University of Arizona

The numbers to know

• The clinical trials that showed St. John's Wort works used extracts standardized to 3–5% hyperforin.
• For depression and anxiety, look for a minimum of 3% hyperforin.
• Products may be standardized for hyperforin (3–5%), hypericin (0.3%), or both.
• Because hyperforin is the primary active constituent, extracts standardized only for hypericin may be less effective.