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,^[53][54] Indian ginseng (not related to Panax ginseng), and wintercherry.^[55] 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).^[56] In modern terms, it is called an adaptogen for similar reasons.^[57]

Beyond those uses, it has been traditionally used as an analgesic, astringent, antispasmodic, and immunostimulant while being used to treat inflammation, cancer, stress, fatigue, diabetes, and cardiovascular complications.^[58][59] The adaptogenic properties of ashwagandha have been emphasized for treating people with stress-related insomnia, debility, and nervous exhaustion.^[60] Ashwagandha has also been reported to have immunostimulant properties that may help to mitigate the negative effects of stress on the immune system.^[60]

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.^[61][62][63] 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.^[8][49]

Ashwagandha’s effects on hormones are not limited to cortisol. Preliminary evidence suggests that 500–600 mg of ashwagandha root extract per day may increase testosterone levels in men when taken over 3–6 months. Improvements in testosterone levels, luteinizing hormone, follicle-stimulating hormone, sperm quality parameters, quality of life, and sexual functioning have been seen with ashwagandha use.^{[64][7][31][52][65][66]} Effects on testosterone are more pronounced in men with infertility and low testosterone levels, though ashwagandha may also boost testosterone levels in healthy men as well.^{[18][24][31][67][52][49]} When supplemented by infertile men, ashwagandha enhanced seminal parameters (e.g. sperm count, motility, quality, and vitality), suggesting that it may help to improve fertility. It’s possible that increased testicular and sperm cell antioxidant status may be partially responsible for these effects.^{[49][52][66][65]}

Ashwagandha may also have beneficial effects on hormone health in women. Though current evidence suggests these beneficial effects are less pronounced than those seen in men, there still isn’t enough evidence to say this conclusively. Ashwagandha apparently also improves sexual function in women, but it’s not clear yet whether subjective well being is similarly enhanced.^[68] One study did find that ashwagandha use in women with menopause increased estrogen while simultaneously lowering follicle-stimulating hormone and luteinizing hormone levels to produce an overall improvement toward menopausal symptom related quality of life.^[32]

Since stress levels are associated with neuroendocrine function, ashwagandha may affect general mental and brain health by reducing stress.^{[69][70][71][72]} In studies where ashwagandha improved subjective signs and symptoms of stress, factors such as anxiety, cognition, and sleep quality also improved, along with cortisol.^[22][11][19] It should be noted that the efficacy of ashwagandha is more pronounced in people reporting both a negative health state and high stress levels.^[73][8]

Ashwagandha is best known as an adaptogen, which are compounds that are believed to mitigate physiologic responses and reduce perceived stress. While ashwagandha’s mechanisms of action aren’t well understood in humans, preclinical studies (animal and cell studies) suggest that it may affect regulation of neuronal excitation (with implications for stress resilience) and/or neuroendocrine receptors (with implications for stress-sensitive psychiatric illnesses, such as depression, schizophrenia, and anxiety). ^{[74][75][76][77]} If ashwagandha affects neuroendocrine activity by modulating the HPA axis, that may be how it purportedly affects the known neuroendocrine system moderators GABA, DHEA, serum BDNF, cortisol, CRP, testosterone, and serotonin. These neuroendocrine moderators are also tied to stress anxiety, depression, schizophrenia, sleep, cognition, and memory outcomes.

Ashwagandha’s ability to enhance GABAergic (neurotransmitter) activity, as shown in preclinical studies, may be responsible for its apparent anxiolytic effects.^{[78][79][80][81][82][83][84] [85][77]} Effectiveness for sleep has been mirrored in some human studies, where a significant increase in sleep quality (among other sleep related parameters such as improvements in sleep latency, efficiency, duration, alertness, and reduced disturbance) occurred when ashwagandha (120–700mg) was taken daily for periods ranging from 1–3 months. ^{[86][87][5][88][89]} It should be noted, however, that prior studies using higher doses of ashwagandha extract (750–2,000 mg, alone or combined with other herbs) did not result in further significant improvements in sleep.^[90][91][92]

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.^[77] In a rodent study, ashwagandha promoted social interaction and attenuated the negative effects of prolonged isolation on social function in rats.^[93] 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. It may also exert some anxiety-reducing effects secondary to the anti-stress properties, via serotonergic and GABAergic signaling. Even lower doses of ashwagandha appear to potentiate the effects of any GABAergic anxiolytic, including alcohol consumption.^{[94][74][95][96][97][75][76][93][98]} In human trials, reduced anxiety has been observed with doses starting at 300 mg, daily up to 12,000 mg/day of ashwagandha over periods ranging from 4–8 weeks. For general stress reduction that hasn’t reached the point of anxiety, 300–600 mg daily appears to be sufficient. ^{[11][13][8][1][99][33][100]}

In animal studies, ashwagandha appears to exert antidepressant effects on its own with a potency comparable to antidepressant medication.^{[101][93][102]} In human studies, 200–400 mg of ashwagandha daily over the course of 30–60 days reduced symptoms of depression in participants with elevated levels of stress.^[18][22]

Ashwagandha may also be helpful in mitigating the signs and symptoms associated with other psychological conditions such as schizophrenia, bipolar disorder, and/or obsessive compulsive disorder. However, more evidence is needed to establish whether any clear effect exists for these specific conditions.^{[14][12][103][104]}

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.^{[105][106][107][108][109][110][74][111]} 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).^{[112][113][114][115]} 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.^{[116][117][118][119][112][120][113]}

In humans, the effects of ashwagandha on brain health are somewhat mixed. In studies where ashwagandha (200–400 mg daily over 1–3 months) enhanced CNS activity and cognition, other factors such as cortisol, quality of life, sleep quality, and subjective measures of stress signs and symptoms also improved. It should also be noted that outcomes such as appetite, anxiety symptoms, short-term memory, serum BDNF, impulsivity, and alertness also saw some benefits in these studies, but to a much lesser extent that can’t be generalized to the broader population at this time.^{[22][121][19][122][57][85]}

It is uncertain whether ashwagandha affects immune health by reducing stress, but chronic stress does tend to suppress healthy immune function.^{[123][71][77]} Ashwagandha’s general immunomodulatory capability (as exerted by 60–500 mg for 1–4 weeks) 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.^{[4][124][29][125][126][127]} These findings, however, still require replication with more robust methodological approaches.

When examining the prevention or treatment of respiratory infection, studies tended to take a more complete ayurvedic approach by using ashwagandha alongside additional therapies and/or herbs. While these studies indicate promising initial results, variation in methods and intervention used may need to be addressed before conclusions can be drawn or generalized.^{[124][128][129][126][127]}

Animal studies suggest that some of ashwagandha’s benefits for immune health may also be due to its antioxidant and anti-inflammatory properties.^[130] A few human clinical trials in adults with and without health conditions appear to reflect this possibility, too. Ashwagandha use (500–5,000 mg daily for 8–12 weeks) correlated with increases in antioxidants and decreases in oxidation markers such as malondialdehyde, along with improvements in exercise recovery, fertility, lung function, oxygen uptake, perceived stress signs and symptoms, and quality of life.^[27][66][28] Several studies have also explored ashwagandha for treating arthritis (500–1,000 mg daily for 8–12 weeks), where anti-inflammatory capacity was the proposed mechanism of action, though this mechanism and effect still has yet to be confirmed.^{[131][132][133]}

Oral supplementation of ashwagandha in people with no health conditions appears to improve cardiorespiratory parameters during exercise, notably VO₂ max.^[134] Increases in power output in sedentary people with no health conditions who start resistance training (750–1,250mg daily for one month) and also those who undergo no training (600 mg daily for two months) have been published.^[92][24] Ashwagandha (120–1,250 mg daily for 2–12 weeks) reportedly also improves VO₂max, upper and lower body strength, lower body power, and recovery in both trained and untrained athletes.^{[6][26][15][25][134][27][5][24][6]} Ashwagandha has also been shown to improve endurance performance by increasing levels of hemoglobin^[6] (the protein in red blood cells responsible for transporting oxygen to the rest of the body) but more studies are needed to confirm this effect. Ashwagandha (600–1,250 mg daily for 1–2 months) in sedentary people with no health conditions may increase lean mass and decrease fat mass, but the results thus far have been mixed.^[92][24]

Animal studies suggest ashwagandha may be cardioprotective against a variety of insults.^{[135][136][137]} 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.^[134]

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. The reduction in LDL cholesterol actually appears to be a per se mechanism of action rather than just fixing a metabolic abnormality, and occurs in normal rats as well as those with metabolic ailments.^[130][138] A reduction in LDL cholesterol has been confirmed in people with no health conditions taking ashwagandha (750–1,250 mg for one month), though there was no indication of changes in triglycerides in these same individuals over the same period.^[92] A mild reduction in triglycerides has been associated with oral ingestion of ashwagandha when taken by people with metabolic syndrome.^[92][139]

In rodent models of diabetes, ashwagandha reduced blood glucose when given at the standard oral doses, with a potency comparable to reference drugs such as glipizide.^{[140][141][138]} Similarly, there appears to be a mild reduction in blood glucose when supplemented (1,200 mg daily for 30 days) by people with metabolic syndrome (insulin resistance).^[139]

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.^{[142][143][144][145]} 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.^[73]

What is Ashwagandha?

Ashwagandha is a traditional Indian medicine (Ayurveda) that is known to be associated with male virility and vitality; a common supplement to recommend to men that are feeling past their prime and a traditional medicine with a surprisingly large amount of evidence overall. It does seem to have some anti-stress effects due to having the properties of an adaptogen.

Among the adaptogens and traditional medicine, however, ashwagandha is one of the few associated with masculinity. Since anything that can be named a testosterone booster gets praise faster than it gets research, many people are wondering whether ashwagandha can increase testosterone or whether it is overhyped.

What does it do?

When it comes to the topic of testosterone, the first study to find an effect was one in male rats where an increase was seen.^[51] When later tested in men suffering from some degree of infertility, improvements in sperm quality came alongside subtle boosts in testosterone around the range of 14-40%^[52] or 10-22%^[49].

While a promising supplement for fertility, it should be stated that supplements that can provide antioxidant support to the testicles are at times associated with an increase in testosterone in infertile but not otherwise fertile men (Vitamin E and CoQ10, for example). Other profertility drugs, such as D-Aspartic acid, are commonly confused with testosterone boosting supplements when the benefits seen in infertile men are erroneously extrapolated.

However, despite all that, at least one study has found a mild increase in testosterone in otherwise healthy men subject to weight training by 15%.^[24] It is not likely that a 15% increase in testosterone will result in major changes in muscularity, but an earnest increase in testosterone in healthy young men by a dietary supplement is quite rare.

While it is more likely a profertility agent, we cannot deny a possibility that ashwagandha could increase testosterone. However, evidence at this time is quite limited.