Rhodiola rosea crashed the growing natural health party when a rigorous Swedish case study suggested rhodiola’s ability to quicken memory, improve attention span, sharpen mental performance, alleviate depression, soothe mental and physical fatigue and improve human focus in difficult circumstances. (The exact extract used in that study was SHR-5, a proprietary rhodiola rosea extract manufactured and distributed by the Swedish Herbal Institute.)
Rigorous case studies suggest genuine neurochemical mechanisms produce these positive rhodiola benefits. The most well-known case studies were conducted by Dr. Richard P. Brown, an associate clinical professor of psychiatry at Columbia University College of Physicians and Surgeons, and Dr. Patricia L. Gerbarg, an assistant clinical professor of psychiatry at New York Medical College, Dr. Philip R. Muskin, the Chief of Consultation-Liaison Psychiatry at the Columbia University Medical Center and a Professor of Clinical Psychiatry at Columbia University, and reported in their books The Rhodiola Revolution and How to Use Herbs and Nutrients in Mental Health Care (those are links to these books on Amazon.com, where you can buy them and then read them for yourself!).
Despite these broad benefits, rhodiola rosea features a remarkably low toxicity level. In standard clinical toxicity studies performed with rats, the lethal dose at which 50 percent of animals perish was determined to be 28.6 ml/kg, which is approximately 3,360 mg/kg. This is extremely low even compared to many common, safe herbs or frequently-consumed over-the-counter pain medications.