Learn all about St. John's Wort

St. John's Wort works through multiple pathways affecting brain chemical systems. Its active compounds, particularly hyperforin, prevent the removal (reuptake) of brain chemicals like serotonin, dopamine, norepinephrine, GABA, and L-glutamate, making more of them available. Additionally, it moderately inhibits monoamine oxidase (MAO) enzymes (enzymes that break down brain chemicals) and reduces the production of substances that cause inflammation which may contribute to depression. These combined actions appear to adjust brain chemical signalling, reduce inflammation in the brain, and help balance the body's stress response system.

St. John's Wort is derived solely from the flowering tops of the Hypericum perforatum plant, a yellow-flowering perennial herb native to Europe and Asia but now naturalized in many parts of the world. The plant contains over two dozen bioactive compounds concentrated in its bright yellow flowers, which release a red pigment when crushed. There are no dietary sources of St. John's Wort's specific compounds, making it accessible only through harvesting the plant or in supplement form. Commercial preparations typically use standardized extracts to ensure consistent levels of key compounds like hypericin and hyperforin.