Ashwagandha, an Ayurvedic wonder herb?

Withania somnifera, commonly known as Ashwagandha, is a plant belonging to the family of Solanaceae. It is widely used in Ayurvedic medicine. The plant is promoted as an immunomodulator, anti-inflammatory, anti-stress, anti-Parkinson, anti-Alzheimer, cardioprotective, neural and physical health enhancer, neuro-defensive, anti-diabetic, aphrodisiac, memory-boosting, and ant-cancer remedy. It contains diverse phytoconstituents including alkaloids, steroids, flavonoids, phenolics, nitrogen-containing compounds, and trace elements.

But how much of the hype is supported by evidence? Unsurprisingly, there is a shortage of good clinical trials. Yet, during the last few years, a surprising number of reviews of the accumulating evidence have emerged:

• One review suggested that pre-clinical, as well as clinical studies, suggest the effectiveness of Withania somnifera (L.) against neurodegenerative disease.
• A further review suggested a potential role of W. somnifera in managing diabetes.
• A systematic review of 5 clinical trials found that W. somnifera extract improved performance on cognitive tasks, executive function, attention, and reaction time. It also appears to be well tolerated, with good adherence and minimal side effects.
• Another systematic review included 4 clinical trials and reported significant improvements in serum hormonal profile, oxidative biomarkers, and antioxidant vitamins in seminal plasma. No adverse effects were reported in infertile men taking W. somnifera treatment.
• Another review concluded that the root of the Ayurvedic drug W. somnifera (Aswagandha) appears to be a promising safe and effective traditional medicine for management of schizophrenia, chronic stress, insomnia, anxiety, memory/cognitive enhancement, obsessive-compulsive disorder, rheumatoid arthritis, type-2 diabetes and male infertility, and bears fertility promotion activity in females adaptogenic, growth promoter activity in children and as adjuvant for reduction of fatigue and improvement in quality of life among cancer patients undergoing chemotherapy.
• A systematic review of 13 RCTs found that Ashwagandha supplementation was more efficacious than placebo for improving variables related to physical performance in healthy men and women.
• Another systematic review concluded that Ashwagandha supplementation might improve the VO_2max in athletes and non-athletes.

Impressed?

This certainly looks as though that this plant is worthy of further study. But I can never help feeling a bit skeptical when I hear of such a multitude of benefits without evidence for adverse effects (other than minor upset stomach, nausea, and drowsiness).