Ashwagandha (Withania somnifera), also known as Indian ginseng, is a herb used in Ayurveda, the traditional medicine of India.

Various parts of the plant are used, but the most common supplemental form is an extract of its roots.

It’s classified as an adaptogen, meaning it’s purported to enhance the body’s resilience to stress.

How it works

Ashwagandha’s effects in humans involves the plant’s influence on the hypothalamic-pituitary-adrenal (HPA) axis as evidenced by its ability to affect cortisol levels.


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.

1. Hormones

In animal models, ashwagandha appears to reduce the stress-related increase in 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 with mild improvements in male fertility.

In a randomized controlled trial, women with sexual dysfunction who supplemented with ashwagandha experienced improvements in sexual function (Study).

2. Mental/Brain health

Ashwagandha has shown to improve symptoms of stress, fatigue, factors such as anxiety, cognition, memory, attention and sleep quality.

3. Immunity

Animal studies suggest that some of ashwagandha may improve immune health due to its antioxidant and anti-inflammatory properties.

4. Exercise performance and body composition

It has shown to improve VO2 max, power output, endurance performance, with minor effects on body composition.

5. Metabolic health

It seems to have some cardio-protective and glucose lowering properties.

6. Cancer metabolism

It has shown to have some anti-cancer effects (inhibits metastasis, proliferation and angiogenesis), reduce chemotherapy induced side effects (neutropenia and fatigue) and improve quality of life when used as adjuvant therapy.


Studies on ashwagandha have used daily dosages ranging from 120–5,000 mg of a root extract. The most common dosing protocol is 600 mg daily, divided into two doses, with one taken in the morning with breakfast and the other in the evening.

Similarly, 600–1,000 mg daily may be more beneficial than lower doses for athletes undergoing an intensive exercise regimen.

More research is needed to confirm whether doses above 600 mg daily yield greater benefits.

It’s also unknown if taking breaks from ashwagandha or taking it every other day prolongs its effectiveness.

Safety and toxicity

A basic water extract of ashwagandha at 2,000mg/kg in rats failed to exert any clinical or biochemical toxicity over the course of 28 days.

It appears to be safe, but more long-term research specifically designed to evaluate its safety is needed. It may cause mild drowsiness and sedation in some individuals.

Some cases of skin rash, liver toxicity and thyroid dysregulation has also been reported.

Herbal supplements must always be used with caution. Inform your doctor or dietitian if you are undergoing treatment for other conditions before starting ashwagandha supplementation.

~Shwetha Bhatia, Registered Dietitian (India Dietetic Association)

Barbara Melton

Barbara Melton

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