Dietary Supplement Standardized to 0.3% Hypericin Supports a Positive Mental Outlook Source Naturals St. John's Wort 450 is standardized to consistently supply 0.3% hypericin. A daily intake of St. John's wort standardized to 2.7 mg hypericin may support a positive outlook and mood. Benefits may be experienced within 4 to 6 weeks of initial use.