For over 3,000 years, extracts from the ashwagandha plant's roots, berries and leaves have been used to relieve stress, increase energy levels, and improve concentration. 

In Sanskrit, Ashwagandha is a combination of the word ashva, meaning horse, and gandha, meaning smell due to its strong, bitter aroma that can be described as "horsey."

The ashwagandha plant is a small shrub with yellow flowers that's endemic to India and North Africa. Its botanical name is Withania somnifera. It is also known by several other names, including Indian ginseng and winter cherry. It is known as the king of herbs in Ayurveda, a form of alternative medicine based on ancient Indian principles of natural healing. 

Ashwagandha is used as an "adaptogen" to help the body cope with daily stress, and as a general tonic for optimal health.
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10 benefits of ashwagandha that are supported by science.

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It helps reduce stress and anxiety

Ashwagandha is perhaps best known for its ability to reduce stress. In several studies, the results indicate that it notably reduces chronic stress and anxiety. (1 Trusted source)

In a 60-day study in 64 people with chronic stress, those in the group that supplemented with Ashwagandha reported a 69% reduction in anxiety and insomnia, on average, compared with 11% in the placebo group (2 Trusted Source).

In another 6-week study, 88% of people who took ashwagandha reported a reduction in anxiety, compared with 50% of those who took a placebo (3 Trusted Source).

Possible anti-cancer properties

On-going studies are proving that Ashwagandha leaf extract selectively kills tumor cells and is a safe, natural anticancer medicine. There is also evidence that it has the ability to  impede the growth of new cancer cells. (4 Trusted Source):
Animal and test-tube studies have found that withaferin — a compound in ashwagandha —  and its withanolides have been shown to have therapeutic potential against cancer, some of them have also been shown to possess cancer preventive properties.

Withaferin is believed to promote the formation of reactive oxygen species (ROS) inside cancer cells, disrupting their function. It also may cause cancer cells to become less resistant to apoptosis (5 Trusted Source).

Animal studies suggest that it may help treat several types of cancer, including breast, lung, colon, brain, and ovarian cancer (6 Trusted Source, 7 Trusted Source, 8 Trusted Source, 9 Trusted Source, 10 Trusted Source).

In one study, mice with ovarian tumors treated with withaferin alone or in combination with an anti-cancer drug showed a 70–80% reduction in tumor growth. The treatment also prevented the spread of cancer to other organs (11 Trusted Source).

Although no evidence suggests that ashwagandha exerts similar effects in humans, the current research is encouraging.

Can reduce cortisol levels

Cortisol is known as a stress hormone. Adrenal glands release cortisol in response to stress, as well as when your blood sugar levels get too low.

Unfortunately, in some cases, cortisol levels may become chronically elevated, which can lead to high blood sugar levels and increased fat storage in the abdomen.

Studies have shown that ashwagandha may help reduce cortisol levels ( 12 Trusted Source, 13 Trusted Source).

In one study, in chronically stressed adults, those who supplemented with ashwagandha had significantly greater reductions in cortisol, compared with the control group. Those taking the highest dose experienced a 30% reduction, on average (14 Trusted Source).

May reduce symptoms of depression

Although it hasn't been thoroughly studied, a few studies suggest ashwagandha may help alleviate depression (15 Trusted Source).

In one controlled 60-day study in 64 stressed adults, those who took 600 mg of high-concentration ashwagandha extract per day reported a 79% reduction in severe depression, while the placebo group reported a 10% increase (16 Trusted Source).

However, only one of the participants in this study had a history of depression. For this reason, the relevance of the results is unclear.

Regulates blood sugar levels

In several studies, ashwagandha has been shown to lower blood sugar levels. 

It contains phenolic compounds which are known to have anti-diabetic effects. These compounds can help improve insulin sensitivity and stabilize blood sugar levels in diabetics. (17 Trusted Source). 

Several human studies have also been done that indicate that it can reduce blood sugar levels in both healthy and diabetic subjects (18 Trusted Source, 19 Trusted Source).

In a 4-week study in people with schizophrenia, those treated with ashwagandha had an average reduction in fasting blood sugar levels of 13.5 mg/dL, compared with 4.5 mg/dL in those who received a placebo (20 Trusted Source).

Can boost testosterone and increase fertility in men

There is strong evidence that Ashwagandha supplements may have powerful effects on testosterone levels and reproductive health (21 Trusted Source, 22 Trusted Source, 23 Trusted Source, 24 Trusted Source).

In one study in 75 infertile men, the group treated with ashwagandha showed increased sperm count and motility. What's more, the treatment led to a significant increase in testosterone levels (25 Trusted Source).

The researchers also reported that the group who took the herb had increased antioxidant levels in their blood.

In another study, men who received ashwagandha for stress experienced higher antioxidant levels and better sperm quality. After 3 months of treatment, 14% of the men's partners had become pregnant (26 Trusted Source).

May increase muscle mass and strength

Research has shown that ashwagandha may improve body composition and increase strength (27 Trusted Source, 28 Trusted Source, 29 Trusted Source).

In a study to determine a safe and effective dosage for ashwagandha, healthy men who took 750–1,250 mg of pulverized ashwagandha root per day gained muscle strength after 30 days (30 Trusted Source).

In another study, those who took ashwagandha had significantly greater gains in muscle strength and size. It also more than doubled their reductions in body fat percentage, compared with the placebo group (31 Trusted Source).

May reduce inflammation

Several animal studies have shown that ashwagandha helps decrease inflammation (32 Trusted Source, 33 Trusted Source, 34 Trusted Source).

Studies in humans have found that it increases the activity of natural killer cells, which are immune cells that fight infection and help you stay healthy (26 Trusted Source, 27 Trusted Source).

It has also been shown to decrease markers of inflammation, such as C-reactive protein (CRP). This marker is linked to an increased risk of heart disease.

In one controlled study, the group who took 250 mg of standardized ashwagandha extract daily had a 36% decrease in CRP, on average, compared with a 6% decrease in the placebo group (28 Trusted Source).

May lower cholesterol and triglycerides

In addition to its anti-inflammatory effects, ashwagandha may help improve heart health by reducing cholesterol and triglyceride levels.

Animal studies have found that it significantly decreases levels of these blood fats.

One study in rats found that it lowered total cholesterol and triglyceride levels by 53% and nearly 45%, respectively (29 Trusted Source).

While controlled human studies have reported less dramatic results, they have observed some impressive improvements in these markers ( 30 Trusted Source, 31 Trusted Source, 32 Trusted Source).

In a 60-day study in chronically stressed adults, the group taking the highest dosage of standardized ashwagandha extract experienced a 17% decrease in LDL (bad) cholesterol and an 11% decrease in triglycerides, on average (33 Trusted Source). 

May improve brain function, including memory

Test-tube and animal studies suggest that ashwagandha may mitigate memory and brain function problems caused by injury or disease (34 Trusted Source, 35 Trusted Source, 36 Trusted Source, 37 Trusted Source).

Research has shown that it promotes antioxidant activity that protects nerve cells from harmful free radicals.

In one study, rats with epilepsy that were treated with ashwagandha had nearly a complete reversal of spatial memory impairment. This was likely caused by a reduction in oxidative stress (38 Trusted Source).

Although ashwagandha has traditionally been used to boost memory in Ayurvedic medicine, only a small amount of human research has been conducted in this area.

In one controlled study, healthy men who took 500 mg of standardized extract daily reported significant improvements in their reaction time and task performance, compared with men who received a placebo (39 Trusted Source).

Another 8-week study in 50 adults showed that taking 300 mg of ashwagandha root extract twice daily significantly improved general memory, task performance, and attention (40 Trusted Source).

Contraindications and directions for use

• Ashwagandha is a safe supplement for most people, however,  its long-term effects are unknown. It is advisable that certain individuals should not take it, this includes:
• Pregnant and breastfeeding women. 
• People with autoimmune diseases should also avoid ashwagandha unless authorized by a healthcare provider. (This includes people with conditions like rheumatoid arthritis, lupus, Hashimoto's thyroiditis, and type 1 diabetes).
• Those on medication for thyroid disease should be careful when taking ashwagandha, as it may increase thyroid hormone levels in some people.
• It may also decrease blood sugar and blood pressure levels, so medication dosages may need to be adjusted if you take it.
• The recommended dosage of ashwagandha depends on the type of supplement. Extracts are more effective than crude ashwagandha root or leaf powder. Remember to follow instructions on labels.
• Standardized root extract is commonly taken in 450–500-mg capsules once or twice daily.
• It’s offered by several supplement manufacturers and available from various retailers, including health food stores and vitamin shops. There's also a great selection of high-quality supplements available online.
• Although ashwagandha is safe for most people, certain individuals shouldn't use it unless authorized to do so by their healthcare provider. Your Wellbeing standardized root extract is commonly taken in 500-mg capsules once or twice per day for effective results.

In summary

1. Some research suggests that ashwagandha reduces blood sugar levels through its effects on insulin secretion and sensitivity.
2. Animal and test-tube studies have shown that withaferin, a bioactive compound in ashwagandha, promotes the death of tumor cells and may be effective against several types of cancer.
3. Ashwagandha supplements may help lower cortisol levels in chronically stressed individuals.
4. Ashwagandha has been shown to reduce stress and anxiety in both animal and human studies.
5. The limited research available suggests that ashwagandha may help reduce depression.
6. Ashwagandha helps increase testosterone levels and significantly boosts sperm quality and fertility in men.
7. Ashwagandha has been shown to increase muscle mass, reduce body fat, and increase strength in men.
8. Ashwagandha has been shown to increase natural killer cell activity and decrease markers of inflammation.
9. Ashwagandha may help reduce the risk of heart disease by decreasing cholesterol and triglyceride levels.
10. Ashwagandha supplements may improve brain function, memory, reaction time, and the ability to perform tasks.

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