Rhodiola

This is Rhodiola’s most replicated human indication. A double-blind crossover RCT in 56 physicians on night duty found a standardised SHR-5 extract significantly reduced a composite mental-fatigue index in the first two weeks ^{1Reference 1Darbinyan et al. · 2000RCTRhodiola rosea in stress induced fatigue — a double blind cross-over study of a standardized extract SHR-5 — randomised controlled trialView study →}, and a placebo-controlled pilot in students during an exam period reported reduced mental and physical fatigue ^{2Reference 2Spasov et al. · 2000RCTA double-blind, placebo-controlled pilot study of the stimulating and adaptogenic effect of Rhodiola rosea SHR-5 extract on the fatigue of students during an examination period — randomised controlled trialView study →}. A parallel-group RCT in 161 military cadets showed a pronounced anti-fatigue effect at both of two doses, with no advantage to the higher dose ^{3Reference 3Shevtsov et al. · 2003RCTA randomized trial of two different doses of a SHR-5 Rhodiola rosea extract versus placebo and control of capacity for mental work — randomised controlled trialView study →}. A phase III trial in 60 adults with clinically diagnosed stress-related fatigue (576 mg/day SHR-5, 28 days) found improvements in burnout scores, attention, and — notably — a blunted salivary cortisol response to awakening versus placebo ^{4Reference 4Olsson et al. · 2009RCTA randomised, double-blind, placebo-controlled, parallel-group study of the standardised extract SHR-5 of Rhodiola rosea in stress-related fatigue — randomised controlled trialView study →}. Systematic reviews conclude the herb “may” help with fatigue while flagging that most trials carry moderate-to-high risk of bias and lack independent replication ^{7,8Reference 7Hung et al. · 2011Systematic reviewThe effectiveness and efficacy of Rhodiola rosea L.: a systematic review of randomized clinical trialsView study →Reference 8Ishaque et al. · 2012Systematic reviewRhodiola rosea for physical and mental fatigue: a systematic reviewView study →}; open-label burnout and life-stress trials of WS 1375 point the same way but are uncontrolled ^{9,10Reference 9Kasper et al. · 2017Clinical trialMulticenter, open-label, exploratory clinical trial with Rhodiola rosea extract in patients suffering from burnout symptoms — clinical trialView study →Reference 10Edwards et al. · 2012Clinical trialTherapeutic effects and safety of Rhodiola rosea extract WS 1375 in subjects with life-stress symptoms — open-label clinical trialView study →}.

Gap: A well-powered nursing-student RCT actually found Rhodiola worse than placebo for fatigue ^{6Reference 6Punja et al. · 2014RCTRhodiola rosea for mental and physical fatigue in nursing students — randomised controlled trialView study →}, and the positive trials share overlapping authorship and one extract — independent replication is thin.

A 2025 systematic review and meta-analysis of 26 RCTs (668 participants) found Rhodiola supplementation significantly improved VO₂max, time-to-exhaustion, and time-trial performance, with larger VO₂max gains above 600 mg/day ^{20Reference 20Wang et al. · 2025Meta-analysisThe effect of Rhodiola rosea supplementation on endurance performance and related biomarkers — systematic review and meta-analysisView study →}. Acute dosing has the clearest signal: a crossover RCT showed a single 200 mg dose extended time-to-exhaustion and raised VO₂peak ^{17Reference 17De Bock et al. · 2004RCTAcute Rhodiola rosea intake can improve endurance exercise performance — randomised controlled trialView study →}, and a 3 mg/kg acute dose lowered heart rate and perceived exertion during a 6-mile time trial, improving finishing time ^{18Reference 18Noreen et al. · 2013RCTThe effects of an acute dose of Rhodiola rosea on endurance exercise performance — randomised controlled trialView study →}. A separate systematic review confirms acute benefit for endurance and perceived exertion but finds chronic supplementation helps anaerobic performance and muscle damage more than endurance ^{19Reference 19Sanz-Barrio et al. · 2023Systematic reviewRhodiola rosea supplementation on sports performance: a systematic review of randomized controlled trialsView study →}, and another review reports reduced post-exercise muscle damage and oxidative stress ^{21Reference 21Lu et al. · 2022Systematic reviewEffects of Rhodiola rosea supplementation on exercise and sport: a systematic reviewView study →}. A 2024 RCT of pure biosynthetic salidroside (60 mg/day) improved oxygen utilisation and reduced exercise-induced muscle damage, isolating one active constituent ^{22Reference 22Schwarz et al. · 2024RCTSalidroside and exercise performance in healthy active young adults — exploratory randomised, double-blind, placebo-controlled studyView study →}.

Gap: Effect sizes are modest and heterogeneous, protocols vary widely, and most trials carry unclear or high risk of bias; the acute-versus-chronic split means “takes it before a race” and “takes it daily” are not interchangeable claims.

A phase III RCT in 89 adults with mild-to-moderate depression found standardised SHR-5 (340 or 680 mg/day, 6 weeks) significantly improved overall depression, insomnia, and emotional instability versus placebo ^{11Reference 11Darbinyan et al. · 2007RCTClinical trial of Rhodiola rosea L. extract SHR-5 in the treatment of mild to moderate depression — randomised controlled trialView study →}. A US proof-of-concept RCT (n=57) compared Rhodiola, sertraline, and placebo over 12 weeks: Rhodiola produced a smaller, statistically non-significant antidepressant effect than sertraline but caused far fewer adverse events, suggesting a more favourable risk-benefit ratio in milder cases ^{12Reference 12Mao et al. · 2015RCTRhodiola rosea versus sertraline for major depressive disorder — randomised placebo-controlled trialView study →}. A 2025 systematic review and meta-analysis of pharmacological treatments for milder depression found Rhodiola significantly improved depressive symptoms versus placebo ^{14Reference 14Urata et al. · 2025Meta-analysisEfficacy of pharmacological interventions in milder depression — systematic review and meta-analysisView study →}. The proposed mechanism includes inhibition of monoamine oxidase A and B by root extracts, shown ex vivo ^{15Reference 15Van Diermen et al. · 2009In vitroMonoamine oxidase inhibition by Rhodiola rosea L. roots — in vitroView study →}, reviewed alongside broader neuroendocrine effects ^{13Reference 13Amsterdam et al. · 2016ReviewRhodiola rosea L. as a putative botanical antidepressant — reviewView study →}.

Gap: Only two placebo-controlled RCTs exist, one of them underpowered and null on its primary comparison ^{12Reference 12Mao et al. · 2015RCTRhodiola rosea versus sertraline for major depressive disorder — randomised placebo-controlled trialView study →}; there is no evidence for moderate-to-severe depression, and Rhodiola should not be assumed to substitute for established antidepressants.

The cognitive benefits track the anti-fatigue data: improvements appear mainly as preserved attention, speed, and accuracy when people are tired or stressed, rather than as cognitive enhancement in the rested. The night-duty physician and cadet RCTs measured cognition through fatigue indices and found gains during the treatment period ^{1,3Reference 1Darbinyan et al. · 2000RCTRhodiola rosea in stress induced fatigue — a double blind cross-over study of a standardized extract SHR-5 — randomised controlled trialView study →Reference 3Shevtsov et al. · 2003RCTA randomized trial of two different doses of a SHR-5 Rhodiola rosea extract versus placebo and control of capacity for mental work — randomised controlled trialView study →}. A double-blind RCT of ADAPT-232 — a fixed combination of Rhodiola, Schisandra, and Eleutherococcus — improved attention, speed, and accuracy two hours after a single dose in stressed women ^{16Reference 16Aslanyan et al. · 2010RCTDouble-blind, placebo-controlled, randomised study of single dose effects of ADAPT-232 on cognitive functions — randomised controlled trialView study →}, though as a combination product it cannot isolate Rhodiola’s contribution. Reviews frame the cognitive effect as secondary to reduced fatigue and stress load ^{13Reference 13Amsterdam et al. · 2016ReviewRhodiola rosea L. as a putative botanical antidepressant — reviewView study →}.

Gap: Some of the cognitive evidence comes from multi-herb formulations, and Cropley’s mono-extract trial found no cognitive change despite mood improvement ^{5Reference 5Cropley et al. · 2015The effects of Rhodiola rosea L. extract on anxiety, stress, cognition and other mood symptoms — controlled trialView study →} — the pro-cognitive claim is real only under fatigue, not as a general nootropic.

The strongest antioxidant evidence is indirect but human: the 2025 endurance meta-analysis found Rhodiola supplementation raised total antioxidant capacity and superoxide dismutase while lowering malondialdehyde (a lipid-peroxidation marker) across exercise trials ^{20Reference 20Wang et al. · 2025Meta-analysisThe effect of Rhodiola rosea supplementation on endurance performance and related biomarkers — systematic review and meta-analysisView study →}, and an exercise systematic review reported enhanced antioxidant capacity and reduced oxidative stress ^{21Reference 21Lu et al. · 2022Systematic reviewEffects of Rhodiola rosea supplementation on exercise and sport: a systematic reviewView study →}. At the constituent level, salidroside activates the Nrf2 antioxidant pathway in cell and animal models, which underlies much of the mechanistic story for its neuro- and cardioprotective effects ^{23Reference 23Zhang et al. · 2023Meta-analysisNeuroprotective mechanisms of salidroside in Alzheimer’s disease — systematic review and meta-analysis of preclinical studiesView study →}.

Gap: Human antioxidant data are confined to the exercise setting and to biomarkers rather than clinical endpoints; the broader antioxidant claim leans on salidroside in vitro, not the whole root in people.

A 2023 systematic review and meta-analysis of 20 preclinical studies found salidroside improved behavioural and biochemical markers in animal models of Alzheimer’s disease, acting through anti-oxidative, anti-inflammatory, and anti-apoptotic pathways ^{23Reference 23Zhang et al. · 2023Meta-analysisNeuroprotective mechanisms of salidroside in Alzheimer’s disease — systematic review and meta-analysis of preclinical studiesView study →}. Salidroside also shows neuroprotection in animal and cell models of cerebral ischaemia and inflammation, and root extracts inhibit MAO-A and MAO-B ex vivo — an activity relevant to both mood and neuronal survival ^{15Reference 15Van Diermen et al. · 2009In vitroMonoamine oxidase inhibition by Rhodiola rosea L. roots — in vitroView study →}.

Gap: Every neuroprotection finding is preclinical; there are no human trials in dementia, stroke, or neurodegeneration, and salidroside’s poor oral bioavailability is a real barrier to translating cell-level potency into clinical effect.

Most cardioprotective evidence is preclinical and constituent-level: salidroside reduces myocardial ischaemia-reperfusion injury and anthracycline-induced cardiotoxicity in animal and cell models through AMPK, anti-ferroptosis, and antioxidant mechanisms ^{23Reference 23Zhang et al. · 2023Meta-analysisNeuroprotective mechanisms of salidroside in Alzheimer’s disease — systematic review and meta-analysis of preclinical studiesView study →}. The one human signal is a small randomised trial in which salidroside reduced early left-ventricular systolic dysfunction in patients receiving the chemotherapy agent epirubicin ^{31Reference 31Zhang et al. · 2012RCTProtective effects of salidroside on epirubicin-induced early left ventricular regional systolic dysfunction in patients with breast cancer — randomised controlled trialView study →}.

Gap: Whole-root Rhodiola has essentially no cardiovascular outcome data in people; the single positive human trial is small, in a narrow chemotherapy setting, and used isolated salidroside rather than the standardised extract sold as a supplement.

An open trial in 80 mildly anxious adults (2 × 200 mg Vitano daily, 14 days) reported significant reductions in self-rated anxiety, stress, anger, confusion, and depression versus an untreated control, with a favourable tolerability profile ^{5Reference 5Cropley et al. · 2015The effects of Rhodiola rosea L. extract on anxiety, stress, cognition and other mood symptoms — controlled trialView study →}. The EMA lists “slight anxiety” among the stress-related symptoms covered by Rhodiola’s traditional-use recognition.

Gap: The only dedicated anxiety trial was not placebo-controlled, so a placebo contribution cannot be excluded, and no cognitive benefit accompanied the mood change ^{5Reference 5Cropley et al. · 2015The effects of Rhodiola rosea L. extract on anxiety, stress, cognition and other mood symptoms — controlled trialView study →} — the anxiety claim is suggestive, not established.

The rationale is mechanistic: salidroside and tyrosol from R. crenulata extracts preserve Na⁺/K⁺-ATPase expression under hypoxia via the ROS-AMPK-PKCξ pathway in vitro, which was proposed to explain protection against high-altitude pulmonary problems ^{25Reference 25Lee et al. · 2013In vitroRhodiola crenulata and its bioactive components, salidroside and tyrosol, reverse the hypoxia-induced reduction of Na,K-ATPase expression — in vitroView study →}. When tested directly, however, a randomised, double-blind, placebo-controlled crossover trial in 102 people ascending rapidly to 3,421 m found R. crenulata extract (800 mg/day) gave no reduction in the incidence or severity of acute mountain sickness ^{24Reference 24Chiu et al. · 2013RCTRhodiola crenulata extract for prevention of acute mountain sickness — randomised, double-blind, placebo-controlled crossover trialView study →}.

Gap: The supporting mechanism is in vitro and uses R. crenulata, not R. rosea; the only powered human RCT was flatly negative — this indication is essentially unsupported despite its popular reputation.

Rhodiola rosea is well tolerated in short-term human trials, with adverse events that are mostly mild (occasional dizziness, dry mouth, or sleep disturbance) and no serious reactions attributed to the extract across the controlled studies ^{4,11,12Reference 4Olsson et al. · 2009RCTA randomised, double-blind, placebo-controlled, parallel-group study of the standardised extract SHR-5 of Rhodiola rosea in stress-related fatigue — randomised controlled trialView study →Reference 11Darbinyan et al. · 2007RCTClinical trial of Rhodiola rosea L. extract SHR-5 in the treatment of mild to moderate depression — randomised controlled trialView study →Reference 12Mao et al. · 2015RCTRhodiola rosea versus sertraline for major depressive disorder — randomised placebo-controlled trialView study →}. In a head-to-head trial, Rhodiola caused markedly fewer adverse events than sertraline (30% vs 63%) ^{12Reference 12Mao et al. · 2015RCTRhodiola rosea versus sertraline for major depressive disorder — randomised placebo-controlled trialView study →}. The main safety consideration is drug interactions: Rhodiola potently inhibits CYP3A4 and P-glycoprotein in vitro ^{26Reference 26Hellum et al. · 2010In vitroPotent in vitro inhibition of CYP3A4 and P-glycoprotein by Rhodiola rosea — in vitroView study →} and contains two constituents (rhodiosin, rhodionin) that inhibit CYP2D6 in vitro ^{27Reference 27Xu et al. · 2013In vitroTwo potent cytochrome P450 2D6 inhibitors found in Rhodiola rosea — in vitroView study →}, and a controlled human study found a modest but real reduction in CYP2C9 activity, which could matter for narrow-therapeutic-index drugs such as warfarin and phenytoin ^{28Reference 28Thu et al. · 2016RCTEffect of commercial Rhodiola rosea on CYP enzyme activity in humans — randomised cross-over studyView study →}. Because of its stimulant-like activation, Rhodiola is generally taken earlier in the day and used with caution alongside antidepressants (particularly MAO inhibitors, given its ex vivo MAO-inhibiting activity) ^{15Reference 15Van Diermen et al. · 2009In vitroMonoamine oxidase inhibition by Rhodiola rosea L. roots — in vitroView study →}.

Scope note: drug interactions have been assessed (in vitro CYP3A4/CYP2D6/P-gp inhibition plus a controlled human CYP-cocktail study showing CYP2C9 reduced ~21%), most relevant for narrow-therapeutic-index CYP2C9 substrates. Pregnancy and lactation have not been assessed in humans.