Rhodiola rosea is a perennial plant found in colder regions such as Scandinavia, the mountains of Central Asia, and the Arctic. In traditional herbal medicine, it is used to enhance performance and reduce fatigue. Extracts of Rhodiola roots comprise about 140 distinct compounds, including polyphenols salidroside (rhodioloside), rosin, and rosavin, but it remains unclear which—if any—confers Rhodiola's purported benefits. While Rhodiola supplements are generally safe for healthy people, there is very little evidence that they have cognitive benefits.
While some clinical trials have examined the effects of Rhodiola rosea on cognitive function, the quality of many were suboptimal and none have directly tested whether it can prevent age-related cognitive decline or dementia. Our search identified:
• 1 systematic review analyzing the effects of Rhodiola on physical and mental fatigue
• 5 randomized, controlled trials examining the effects of Rhodiola on cognitive function
• 2 open-label clinical trials: 1 in older adults and 1 in mildly anxious people
• Numerous preclinical studies
Rhodiola is reported to enhance energy levels and control how the body responds to stress, both of which can affect brain health, but the clinical evidence to support these assertions is lacking due to the low quality of many trials. No clinical studies have tested whether Rhodiola can prevent age-related cognitive decline or dementia. In one well-conducted randomized, controlled clinical trial in male students (17–19 years old), researchers found no improvement in cognitive scores after 20 days of supplementation . And a double-blind cross-over study with 18 healthy adults prescribed 3 mg/kg of Rhodiola found no effects on mood or cognitive function . A systematic review examining the role of Rhodiola on mental fatigue reported that it was effective in some studies while not in others, but methodological flaws in the studies precluded accurate assessment of its efficacy . More rigorous randomized controlled trials are needed to determine the effect of Rhodiola on mental fatigue.
While preclinical studies have suggested potential benefits, the research is inconclusive. One study, for example, showed that Rhodiola can act as a powerful antioxidant, but was toxic to isolated neurons .
There is no evidence that Rhodiola supplements can treat dementia. While there is some evidence that Rhodiola may help combat symptoms experienced by dementia patients, such as insomnia, fatigue, and anxiety [5-7], none of these trials included patients with dementia.
Rhodiola is considered generally safe for healthy adults . Although rare, reported side effects include headache, mild dizziness, dry mouth, sleepiness, insomnia, hyperactivity, jitteriness, agitation, and diarrhea . Safety has not been assessed extensively for treatment exceeding three months.
NOTE: This is not a comprehensive safety evaluation or complete list of potentially harmful drug interactions. It is important to discuss safety issues with your physician before taking any new supplement or medication.
Rhodiola supplements are commercially available in both capsule and liquid forms. However, quality and composition of supplements can vary widely by manufacturer. Although there is no official recommended dose, clinical studies have used doses from 50 to 1500 mg/day with no reports of major adverse effects. Most commonly used doses that are proposed to be safe range from 200 to 600 mg/day .
Rhodiola Fact Sheet from the National Center for Complementary and Integrative Health