Ashwagandha

What is ashwagandha?

Ashwagandha (Withania somnifera), also known as Indian ginseng, is an herb used in Ayurveda, the traditional medicine of India. Its root has a horsey smell and is said to confer the strength and virility of a horse. In Sanskrit, ashva means “horse” and gandha means “smell. Various parts of the plant are used, but the most common supplemental form is an extract of its roots. Its use as part of the Ayurvedic system usually involves more than just the herb alone. Ashwagandha is classified as an adaptogen, meaning it’s purported to enhance the body’s resilience to stress. Rodent and cell culture studies suggest that ashwagandha may provide a wide range of health benefits, but evidence in human studies has thus far varied depending on the health state and population of interest.

What are the known traditional, historical, and cultural uses of ashwagandha?

Withania somnifera (of the family Solanaceae) is a highly esteemed medicinal herb in Ayurveda and is most popularly known as ashwagandha, although other common names include the King of Ayurveda, Indian ginseng (not related to Panax ginseng), and wintercherry. The herb is classified as rasayana in Ayurvedic medicine, which suggests it has the ability to affect health, wellness, and vitality. It is also classified as bhalya (increases strength) and vajikara (aphrodisiac). In modern terms, it is called an adaptogen for similar reasons.

What are ashwagandha’s main benefits?

Ashwagandha is best known for its anxiolytic (anti-anxiety) and stress-relieving effects. It also seems to reduce cortisol levels. In addition, a growing body of evidence supports the efficacy of ashwagandha for improving total sleep time and sleep quality in people with and without insomnia. Since the stress response has a wide range of effects on the human body, it is possible this action is where ashwagandha’s reputation for being a ‘cure all’ originated. There is increasing support for the use of ashwagandha in the context of health states that are typically affected by a chronic stress response. Ashwagandha research in cardio-respiratory and musculoskeletal performance enhancements has shown promise for both athletes and non-athletes. Similarly, ashwagandha may also improve immune health, women’s health, men’s health, and sexual health. Unfortunately, due to inconsistencies in the research, it has been difficult to form any direct conclusions.

Does ashwagandha affect hormone health?

Ashwagandha has shown mixed effects on hormone health measures such as cortisol, testosterone, estrogen, luteinizing hormone, follicle-stimulating hormone, prolactin, and thyroid hormones in human studies. In animal models, ashwagandha appears to reduce the stress-related increase in corticosteroids in serum, and at the higher doses of supplementation (though still within the doses humans use), to fully normalize cortisol to control levels. The cortisol reductions seen in chronically stressed adults with ashwagandha (300–500 mg over 60–90 days) tend to be in the range of 20%–50% from baseline values, with more of an effect seen in people who self-report high levels of stress.

Does ashwagandha affect general mental and brain health?

Since stress levels are associated with neuroendocrine function, ashwagandha may affect general mental and brain health by reducing stress. In studies where ashwagandha improved subjective signs and symptoms of stress, factors such as anxiety, cognition, and sleep quality also improved, along with cortisol. It should be noted that the efficacy of ashwagandha is more pronounced in people reporting both a negative health state and high stress levels.

Does ashwagandha affect specific mental health conditions?

Ashwagandha’s potential to moderate the HPA axis, as well as GABAergic and serotonergic activity, may explain at least some of its proposed effects on mental health, but more research is needed to better understand the underlying mechanisms. In a rodent study, ashwagandha promoted social interaction and attenuated the negative effects of prolonged isolation on social function in rats. It is not clear whether the same effects might be seen in humans, but this could be a well-timed avenue for further research to explore. Ashwagandha’s anti-stress effects seem to be related to corticosterone signaling and suppression of neuronal excitation (through modulating nNOS and glutamate signaling) in response to stress.

Does ashwagandha affect brain health?

Ashwagandha may have beneficial effects on brain health by promoting the formation of neurons and enhanced neuroprotection. In animal models, ashwagandha increased antioxidant activity in the brain and prevented excessive levels of corticosterone, which may confer neuroprotection from a variety of cognitive diseases associated with oxidative stress. When looking at the mechanisms behind neurogenesis in preclinical models, several of ashwagandha’s chemical components have been shown to stimulate the production of BDNF (a neurotrophic growth agent). In vitro cell studies suggest that ashwagandha’s constituents may induce neurogenesis at dosages that are reasonably seen in oral supplements, but this effect has not yet been confirmed in humans.

Does ashwagandha affect immune health?

It is uncertain whether ashwagandha affects immune health by reducing stress, but chronic stress does tend to suppress healthy immune function. Ashwagandha’s general immunomodulatory capability has been explored through direct assessment of immune parameters (immunoglobulins A, M, G, cytokines, natural killer cell content/activity, and lymphocytes) with encouraging results for fighting infection. These findings, however, still require replication with more robust methodological approaches.

Does ashwagandha affect physical fitness and body composition?

Oral supplementation of ashwagandha in people with no health conditions appears to improve cardiorespiratory parameters during exercise, notably VO max. Increases in power output in sedentary people with no health conditions who start resistance training and also those who undergo no training have been published. Ashwagandha reportedly also improves VO max, upper and lower body strength, lower body power, and recovery in both trained and untrained athletes. Ashwagandha has also been shown to improve endurance performance by increasing levels of hemoglobin, but more studies are needed to confirm this effect.

Does ashwagandha affect cardiometabolic health?

Animal studies suggest ashwagandha may be cardioprotective against a variety of insults. The exact mechanism responsible for this effect is still unconfirmed, as limited evidence indicates ashwagandha has no clear influence on blood pressure parameters in people with no health conditions. In rodent studies, ashwagandha appears to improve the lipoprotein profile with a mild increase in HDL-C and more notable reductions in LDL-C and total cholesterol.

What else has ashwagandha been studied for?

Cancer therapy is a newer frontier for exploring ashwagandha as a potential therapy. Preclinical studies on withaferin A (an isolated constituent of ashwagandha) indicate it may inhibit or control cancer metastasis in animal and cell models. In humans undergoing chemotherapy for breast cancer, ashwagandha as a whole herb supplement has demonstrated an increase in well-being and physical/emotional function, and a reduction in fatigue, insomnia, and pain.

What are ashwagandha’s main drawbacks?

Ashwagandha appears to be safe, but more long-term research specifically designed to evaluate its safety is needed. Ashwagandha may cause mild drowsiness and sedation for some people. Some case reports have suggested adverse effects such as rash or thyroid dysregulation may occur with ashwagandha use, but the same adverse events were not mirrored in a larger sample safety study. Several case reports have also raised concerns regarding the rare occurrence of liver toxicity with ashwagandha use, but similarly, toxicity has not been observed in clinical safety trials.