Overview

• St John’s Wort, saffron, probiotics, vitamin D and mixed omega-3s are the only products supported by more than ten depression trials each
• Eighteen supplements including folic acid, lavender, zinc, tryptophan, rhodiola and lemon balm show emerging evidence with two to nine trials apiece
• Over 40 products have only a single study or none, leaving common herbs such as ginseng, gingko and peppermint unevaluated for depressive symptoms
• Just 69% of trials fully documented side effects, prompting calls for stricter safety protocols and comprehensive adverse-event reporting
• Authors and experts urge new research on supplement use alongside talking therapies, health-service cost analyses and under-researched popular products