Food is medicine: The science behind ashwagandha

Key takeaways:

• Ashwagandha is one of the most popular botanical supplements today.
• The supplement may offer benefits for sleep quality and anxiety, but the evidence is unclear.

Ashwagandha supplementation could be useful for anxiety and sleep, but the research is limited, so its clinical implications are uncertain, according to an expert.

Ashwagandha supplements have skyrocketed in popularity in recent years, according to a report from the American Botanical Council. In 2021, consumers spent 225% more on the supplements than the previous year, and sales exceeded $92,300,000 — representing the strongest mainstream sales growth for that supplement for the second year straight.

Barbara C. Sorkin, PhD, director of the Botanical Research Centers Program at the NIH’s Office of Dietary Supplements (ODS), told Healio that ashwagandha is not a vitamin or mineral but a botanical — meaning that unlike other essential nutrients, it does not have “an established role in human nutrition.”

“Ashwagandha has been used in traditional Ayurvedic and Unani medicine systems of India as an adaptogen, which is loosely defined as a compound or product that increases the ability of a person to resist, adapt or become resilient in nonspecific ways to biological, physical, or chemical stressors,” Sorkin said.

Summary of evidence

Ashwagandha has been studied for several areas of health. Sorkin said most trials used extracts made from the plant’s roots, but some have used extracts from leaves as well.

“While these extracts may contain hundreds of different compounds, a group of structurally related chemicals — steroidal lactones known as withanolides — have been believed to be responsible for many of ashwagandha’s proposed effects, but some evidence suggests that other components may also be involved,” she said.

Some of the notable research areas of ashwagandha supplementation include sleep quality, anxiety and general stress, Sorkin said.

“Several clinical trials in people who reported having high stress report that taking ashwagandha extracts may help reduce stress, but these results should be used with care, as the sample sizes for these studies are quite small,” Sorkin said.

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For example, in a 2019 randomized, double-blind, placebo-controlled trial, researchers allocated 60 participants to take either 240 mg of a standardized ashwagandha extract daily or a placebo for 60 days. To measure the antistress and mood-enhancing effects of ashwagandha, researchers administered the Depression, Anxiety and Stress Scale -21 (DASS-21) and the Hamilton Anxiety Rating Scale (HAM-A), and they also examined hormonal changes in participants that are commonly associated with stress and anxiety, such as cortisol, dehydroepiandrosterone sulfate (DHEA-S) and testosterone levels. The researchers found that, compared with placebo, the supplement was associated with a near-significant reduction in the DASS-20 (P = 0.096) and a statistically significant reduction in the HAM-A (P = 0.04). Ashwagandha was also associated with greater reductions in cortisol (P < .001) and DHEA-S (P = .004) vs. placebo. Over time, men experienced increased testosterone levels (P = .038), but this effect was not seen in women (P = .989), and the change was not significant compared with placebo (P = .158) These results indicate that ashwagandha supplementation may offer significant emotional improvements over time for healthy, mildly anxious adults, but further study with larger, more diverse sample sizes is needed to substantiate their findings, the researchers said. Sorkin also said that, although the research is limited, “a few small clinical trials report that taking ashwagandha extracts may help improve sleep.”

A 2020 double-blind, randomized, parallel-group, placebo-controlled study evaluated the effect ashwagandha root extract had on sleep quality among both healthy patients (n = 40) and those who had insomnia (n = 40). The researchers found that ashwagandha root extract significantly improved sleep parameters in patients who were healthy and those who had insomnia, but the improvement was more significant among those with insomnia. The findings indicate that ashwagandha root extract “has an admirable effect” in improving sleep, they wrote.

Some research has also investigated ashwagandha for other possible benefits. For example, a double-blind, randomized, placebo-controlled trial evaluated ashwagandha root extract’s potential impact on cardiorespiratory endurance and recovery.

The study, which included 50 healthy athletic adults in India, revealed that the root extract seems to improve quality of life and cardiorespiratory endurance in this population; compared with the placebo group, the ashwagandha group saw a statistically significant improvement in VO₂ max — a measure of how much oxygen your body uses while exercising — as well as improved energy, fitness and fatigue recovery. The researchers also noted that “the stress management capability of the subjects was improved for the ashwagandha group” and that there were no adverse events.

Safety

Sorkin said that ashwagandha supplementation seems to be “well tolerated for up to about 3 months of use,” but the safety of using the botanical beyond that point is unknown.

“Side effects are usually mild, including stomach upset, loose stools, nausea and drowsiness,” she said. “Serious side effects, including adverse effects on liver function, have been reported in a few cases. In addition, ashwagandha might affect thyroid function and might interact with thyroid hormone medications and other medications.”

Sorkin also noted that ashwagandha use “is not recommended during pregnancy or lactation, or for people with hormone-sensitive prostate cancer.”

The ODS offers resources for health care providers and consumers. To learn more about ashwagandha and other products, check out the ODS Fact Sheets.

Editor’s Note: Healio is highlighting the clinical value of various supplements. See other installments of the series here:

• Melatonin
• Omega-3
• Zinc and other supplements for immune function
• Vitamin D
• Calcium
• Magnesium
• Folic Acid
• Vitamin B12
• Iodine

References:

• Langade D, et al. J Ethnopharmacol. 2021;doi:10.1016/j.jep.2020.113276.
• Lopresti AL, et al. Medicine. 2019;doi:10.1097/MD.0000000000017186.
• Tiwari S, et al. J Ethnopharmacol. 2021;doi:10.1016/j.jep.2021.113929.
• US Sales of Herbal Supplements Increase by 9.7% in 2021. https://www.herbalgram.org/resources/herbalegram/volumes/volume-19/issue-11-november/news-and-features-1/2021-herb-market-report/. Published November 2022. Accessed March 6, 2024.
• Verma N, et al. Complement Ther Med. 2021;doi:10.1016/j.ctim.2020.102642.