Combatting stress: Efficacy and safety of Rhodiola rosea and Ashwagandha reviewed

Herbal adaptogens—specific botanicals historically used in traditional medicine—enhance the efficiency of the body’s adaptive response to physical, chemical or biological stressors.

Rhodiola rosea​ (Golden root) and Ashwagandha (Withania somnifera ​or Indian ginseng) are classical plant adaptogens that promote stress resilience while counteracting stress-associated alterations such as anxiety, nervousness, irritability, insomnia and depression.

Researchers from Nektium, producers of the standardised Rhodiola rosea​ extract Rhodiolife, and from the University of Las Palmas de Gran Canaria in Spain, evaluated both ingredients in a scientific review study published in the European Journal of Medicinal Plants​.

Analysing existing in vitro​, in vivo​ and clinical trials, they found that the overall evidence indicates that both have effective anti-stress activity, with different mechanisms of action, indicating that Rhodiola rosea​ has more of an energising effect while Ashwagandha has sleep-promoting effects.

The review additionally assessed the evidence on the safety of both adaptogens after Denmark announced a ban on Ashwagandha​ following a risk assessment that failed to establish a safe lower limit for intake.

The review presents a favourable picture of Ashwagandha’s overall safety; however, it showed there is growing data concerning interactions with specific medications and potential adverse effects in susceptible individuals or those with certain health conditions or subclinical disorders.

“Both adaptogens show effective anti-stress activity, but their specific mechanisms of action differ. Rhodiola rosea​, with its impact on the central nervous system, demonstrates improvement in stress-induced fatigue, depression and enhanced mental and physical performance," said Rubén Machín, project manager of research, development and innovation at Nektium. "Ashwagandha, on the other hand, exhibits serotonergic-dependent antidepressant effects and modulates GABAergic neurotransmission, potentially making it more effective against stress-associated anxiety, nervousness and insomnia.”

He added: “Taking into account the endocrine mechanism of action and the most robust evidence of efficacy from clinical trials, Rhodiola rosea​ may tentatively be assigned as a regenerative ‘tonic vitalizing’ adaptogen, supporting stress-associated fatigue and weakness in several physical and psychological contexts. Ashwagandha could be considered as regenerative ‘tonic-nervine’ that counteracts stress-related anxiety and insomnia or drowsiness.”

Bruno Berheide, commercial and partnership director at Nektium, added that the review shows the choice of adaptogen is important in relation to the desired use and target audience.

"For example, Rhodiola rosea​ could be recommended for morning intake due to its energising and vitalising effects, while Ashwagandha could be more suited for evening intake, due to its calming and sleep-promoting effects," he explained. "Likewise, sports people could take advantage of Rhodiola rosea​ to combat fatigue and improve mental and physical performance, while Ashwagandha could be well positioned for individuals wishing to manage their anxiety levels in everyday life.”

Reviewing efficacy and safety

The new review considered more than 70 human clinical trials on Rhodiola rosea​, which were of varying quality in methodology, design and conditions. Despite these limitations, there was a clear level of evidence to demonstrate that Rhodiola rosea​ can effectively combat physical stress-related fatigue, low mood, anxiety, depression and may improve physical-mental working capacity.

Ashwagandha, meanwhile, could work by a similar or additional neuromodulatory mechanism. The clinical efficacy of its preparations and extracts has now been demonstrated across a large number of human trials, which support its potential therapeutic role as an adaptogenic anti-stress agent and in counteracting stress-related conditions, especially anxiety, nervousness and insomnia.

The review found that Rhodiola rosea​ can be considered safe and is generally well tolerated in individuals with a wide variety of health statuses, although it is not recommended in subjects with hyperthyroidism, even subclinical, as it could promote or exacerbate the symptoms of the disease, or in those with hypotension, as it may lower blood pressure.

Additionally, since it may act as an immunostimulant, it is not recommended for patients taking immunosuppressors, especially in patients with autoimmune diseases.

W. somnifera​ root extract has been used as a pro-fertility and aphrodisiac agent in men and women. However, men with hormone-sensitive prostate cancer or prostate hyperplasia should avoid taking as, according to some studies, the plant may increase testosterone production​.  Additionally, it may be contraindicated in women planning on becoming pregnant or who are pregnant, as higher doses of the extract have been used as an abortifacient in traditional Ayurvedic medicine.

However, although a prenatal toxicity study conducted in rodents​ showed no evidence of maternal or fetal toxicity, clinical evidence is still needed to unequivocally confirm the safety of the extract intake during such a sensitive period of life.

The review therefore concludes that several preclinical toxicity/safety studies performed in rodents have provided reasonable evidence of safety.

In 2011, the European Medicines Agency’s herbal monograph on Rhodiola rosea​​ approved its traditional use as an adaptogen for the temporary relief of symptoms associated with stress, such as fatigue, exhaustion and a general sensation of weakness.

Rhodiolife recently received approval and a NPN (Natural Product Number) from Health Canada, which means several recommended health claims can be used: As an adaptogen, to help to temporarily relieve symptoms of stress (such as mental fatigue and sensation of weakness); as an adaptogen, to help support cognitive function (such as mental focus and mental stamina); to help increase energy and resistance to stress; and as a source of antioxidants.

Source: European Journal of Medicinal Plants​
doi: 10.9734/EJMP/2023/v34i111168​
"Adaptogenic Botanicals with Emphasis on Rhodiola rosea​ and Withania somnifera​"
 Authors: Rubén P. Machín et al.