Adaptogens are described as agents that can assist an organism in its physiological adaptation to, and tolerance of, various chronic stressors by increasing the body?s nonspecific resistance and normalising functions. One botanical genus that has been the focus of recent research and commercialization is rhodiola.
The bioactive profile of Rhodiola spp. has centred upon a select duo of marker compounds: salidroside and rosavin. Salidroside is a glucose-linked congener of para-tyrosol, a phenolic constituent. Rosavin is a nonphenolic constituent classified as a phenylpropanoid.
Limiting this review to original clinical research published in the English language, we find the majority of studies being published after 1999. A specific extract of R. rosea, produced by the Swedish Herbal Institute named SHR-5, and marketed as a consumer packaged good with the name Rosenrot, has been the focus of several studies.
In one study, 40 male Indian first-year medical students (at a Russian medical school, 17-19 years of age) took tablets containing either 50mg SHR-5 extract or placebo twice daily for 20 days.1 SHR-5 is standardised to approximately 2.5 per cent salidroside, with rosavin content not being standardised. An exercise capacity test showed no statistically significant difference of SHR-5 over placebo. However, a motor skills test involving a spiraling maze and self-assessed questionnaires of mental fatigue and motivation did show significant improvements relative to the placebo group.
A second study with SHR-5 enrolled 121 Russian military cadets (19-21 years of age) performing night duty and randomised to receive a single dose of two or three capsules containing 185mg SHR-5/capsule, two capsules of a matched placebo or no supplement, at 4 a.m.2 Among the groups receiving SHR-5, their performance in several mental performance tests was superior to that of the placebo (as measured by an ?Anti-Fatigue Index?) with very little difference between the two SHR-5 doses.
A third study enrolled male and female Armenian physicians (24-35 years of age) on night duty and randomly assigned them to receive a placebo or 170mg SHR-5 once daily for two weeks in random order, followed by a two-week washout, and then two weeks of the opposite agent.3 Again, a battery of mental performance tests were administered with some evidence of ?anti-fatigue? effects.
More recently, the effects of a R. rosea extract-containing dietary supplement (Optygen) were evaluated among 17 elite amateur competitive cyclists.4 The cyclists were randomly assigned to ingest six capsules/day for four days and then three capsules/day for an additional 11 days. The Optygen was claimed to provide 100mg R. rosea extract/capsule, standardised to a minimum 2.5 per cent salidroside and 3 per cent rosavins. Also included was 333mg Cordyceps sinensis mycelia biomass with a claimed minimum 7.5 per cent cordycepic acid. All cyclists performed a graded exercise test on a computer-interfaced bicycle ergometer until exhaustion/low pedal rpm. The group receiving the R. rosea-containing extract performed no better than placebo in all measures of performance.
An additional study employing simulated high altitude (reduced oxygen; conditions mimicking elevation at 4,600m) found seven days of ingesting a R. rosea extract without effect on oxygenation but with a possible mitigating role in hypoxia-induced oxidative stress.5
More rigorous clinical investigations, assessing the comparative biological effects of various species of rhodiola are warranted, as no evidence to date points to the superiority of one species over another.6 Additionally, differences in the chemoprofiles of rhodiola species from different regions and new production methods that are sustainable or enhance yield merit keen focus.7,8,9
Anthony Almada, MSc, is president and chief scientific officer of IMAGINutrition Inc. www.imaginutrition.com
Respond: [email protected]
All correspondence will be forwarded to the author.
1. Spasov AA, et al. A double-blind, placebo-controlled pilot study of the stimulating and adaptogenic effect of Rhodiola rosea SHR-5 extract on the fatigue of students caused by stress during an examination period with a repeated low-dose regimen. Phytomedicine 2000; 7:85-9.
2. Shevtsov VA. A randomized trial of two different doses of a SHR-5 Rhodiola rosea extract versus placebo and control of capacity for mental work. Phytomedicine 2000; 7:95-105.
3. Darbinyan V, et al. Rhodiola rosea in stress-induced fatigue ? a double-blind crossover study of a standardized extract SHR-5 with a repeated low-dose regimen on the mental performance of healthy physicians during night duty. Phytomedicine 2000; 7:365-71.
4. Earnest CP, et al. Effects of a commercial herbal-based formula on exercise performance in cyclists. Med Sci Sports Exerc 2004; 36:504-9.
5. Wing SL, et al. Lack of effect of rhodiola or oxygenated water supplementation on hypoxemia and oxidative stress. Wilderness Environ Med 2003; 14:9-16.
6. Abidov M, et al. Effect of extracts from Rhodiola rosea and Rhodiola crenulata (Crassulaceae) roots on ATP content in mitochondria of skeletal muscles. Bull Exp Med Biol 2003; 136:585-7.
7. Lei Y, et al. Interpopulation variability of rhizome essential oils in Rhodiola crenulata from Tibet and Yunnan, China. Biochem Syst Ecol 2004; 32:611-4.
8. Yan X, et al. Soil nutrient factors related to salidroside production of Rhodiola sachalinensis distributed in Chang Bai Mountain. Environ Exp Bot 2004 (in press) DOI:10.1016/j.envexpbot.2004.02.005.
9. Tolonen et al. LC/MS/MS identification of glycosides produced by biotransformation of cinnamyl alcohol in Rhodiola rosea compact callus aggregates. Biomed Chromatogr 2004 (in press) DOI: 10.1002/bmc.355.