Ashwagandha: Traditional Use, Constituents and Evidence

A root with a very long résumé

Somewhere in my nan's garden , between the comfrey patch and the lemon verbena she'd pinch into everything , there was no ashwagandha. That's not a plant that grows in the Adelaide Hills without serious coaxing. But it's been in my reading life for years, and lately it's arrived in earnest on Australian shelves and in the research literature in equal measure. Worth a proper look.

Withania somnifera is a small, woody shrub in the Solanaceae family , nightshades, for those keeping track; native to India, North Africa and parts of the Mediterranean. The dried root and, less commonly, the leaf are the parts used medicinally. Its Sanskrit name translates roughly as "smell of horse", which is accurate and not a selling point. The species epithet, somnifera, means sleep-bearing. Both names tell you something about how this plant has been understood for a very long time.

Traditional use: Ayurveda and beyond

Ashwagandha's place in Ayurvedic medicine stretches back at least 3,000 years. It appears in the Charaka Samhita, one of the foundational Ayurvedic texts, where it's classified as a rasayana, a category of preparations associated with rejuvenation and longevity rather than treatment of a specific illness. That framing matters: rasayana use was about maintaining vitality, not necessarily fixing a named disease. The root was prepared as a powder mixed with milk, ghee, or honey, or as a decoction.

Traditional Unani medicine also incorporated ashwagandha, and it appears in traditional African medicinal systems, particularly in sub-Saharan regions where the plant grows wild. Each tradition developed its own preparation methods and understandings of what the plant does.

Understanding how traditional knowledge systems conceptualise a plant is genuinely useful context for modern researchers, not because it proves efficacy, but because it points toward which biological activities might be worth investigating. That's a distinction worth holding onto. History is a hypothesis generator, not a clinical trial.

Key constituents

The chemistry of ashwagandha root is reasonably well characterised. The primary bioactive class is the withanolides; steroidal lactones unique to the Withania genus. Withaferin A and withanolide D are the most studied. These compounds sit at the centre of most contemporary phytochemistry research on the plant.

Beyond withanolides, the root contains:

• Alkaloids, including somniferine, somnine and anaferine, present in relatively small amounts in the root, more concentrated in the leaves and seeds.
• Saponins, including sitoindosides VII and VIII, which have been investigated for their effects on stress-response pathways.
• Iron in significant concentrations relative to many other roots, which likely contributes to some traditional uses around fatigue.
• Steroidal lactones in the withanolide family continue to attract attention because their structural similarity to active compounds in other plant classes makes them interesting starting points for mechanistic research.

Commercial extracts vary considerably. A standardised extract will specify withanolide content, typically 2.5–5% by weight, though some preparations go higher. That standardisation matters because raw root powder and a concentrated extract are not interchangeable from a research or regulatory standpoint. If you're reading a study, checking what preparation was used and at what withanolide concentration is the first thing to do before drawing any conclusions.

There's an interesting overlap here with how researchers think about bioavailability in plant compounds generally. Fat-soluble constituents like withanolides are absorbed differently depending on the carrier matrix; whether taken with food, in an oil-based preparation, or as a dry powder. Most ashwagandha trials don't report this detail consistently, which is one limitation across the literature.

What the research shows, and what it doesn't

The honest version of this section is shorter than some websites would have you believe.

There's a reasonable body of preclinical work, cell cultures and animal models; examining withanolides and their effects on cortisol-pathway markers, inflammatory signalling molecules and oxidative stress parameters. Some of that work is genuinely interesting mechanistically. But preclinical data does not translate directly to human outcomes, and this is a point the ashwagandha literature needs to hold more carefully than it often does.

Human clinical trials exist but are mostly small. A 2019 randomised, double-blind, placebo-controlled trial published in Medicine (the journal) assessed a root extract in 60 participants over eight weeks, measuring self-reported stress scores and serum cortisol. It found statistically significant differences on both measures in the supplemented group. However, and this is the "but" that matters, the sample size is modest, the follow-up period is short, and the trial was industry-adjacent in its funding. That doesn't invalidate the data; it qualifies it.

A 2021 systematic review in the Journal of Ethnopharmacology assessed 24 human trials and concluded that the methodological quality of ashwagandha research is uneven, with many trials carrying a high risk of bias. Blinding quality, participant dropout rates and heterogeneous outcome measures make meta-analysis genuinely difficult. I'd argue the research is at an "biologically plausible and worth studying" stage, not a "demonstrated effect" stage; and a lot of popular coverage skips that distinction entirely.

Withanolides have also been studied for their potential interactions with several receptor and enzyme systems, including pathways that intersect with the endocannabinoid system. Some preclinical work suggests withanolides may modulate GABA-A receptors and influence stress-axis signalling. This is mechanistically interesting but does not constitute a clinical claim.

Regulation in Australia: what the TGA says

Ashwagandha occupies a relatively uncomplicated regulatory position in Australia compared with, say, kava (which carries import restrictions under the Customs (Prohibited Imports) Regulations 1956) or medicinal cannabis (which sits in Schedule 8 under the Poisons Standard). Ashwagandha root and root extracts are listed in the TGA's permitted ingredients for Listed Medicines, that is, products that can be entered on the Australian Register of Therapeutic Goods (ARTG) via the Listed pathway (AUST L number).

Listed medicines are assessed for safety and quality but not efficacy. A product bearing an AUST L number has passed a safety review and must be manufactured under Good Manufacturing Practice (GMP) conditions. It has not been assessed for whether it actually does what the label implies. That's an important distinction. The TGA requires that therapeutic claims on Listed medicine labels be restricted to low-level, pre-approved indications, something like "traditionally used in Ayurvedic medicine" rather than a specific disease or symptom claim.

The complementary medicine industry in Australia is large. The TGA's post-market monitoring includes random audits of Listed products, and in recent years there have been published compliance actions against ashwagandha products making claims that exceeded what the Listed pathway permits. Anyone seeing a product on an Australian shelf making strong health claims for ashwagandha should check the ARTG number and the listed permitted indications; the TGA's public ARTG search tool makes this easy.

This is where phytomedicine regulation gets genuinely complicated: a traditional use listing is not the same as a clinical evidence base, and the label wording is meant to reflect that. In practice, the line between "traditionally used to support" and a therapeutic claim can be blurry, which is why the TGA enforcement activity in this category matters.

Safety considerations and interactions

Ashwagandha has a generally favourable safety profile in the literature at the doses used in trials. That said, there are important caveats.

Rare cases of drug-induced liver injury potentially associated with ashwagandha products have been published in peer-reviewed literature, including a 2021 case series in Liver International. The causality isn't fully established across all cases and confounding (other supplements, medications, or products in multi-ingredient formulations) complicates the picture. But it's been enough to prompt regulatory communications in some jurisdictions.

Ashwagandha contains compounds with hormonal activity, which raises questions about use alongside thyroid medications or in pregnancy. The evidence base for these interactions is limited but the precautionary logic is reasonable. Anyone on prescription medication, thyroid hormones, immunosuppressants, sedatives, should speak with a healthcare professional before using ashwagandha preparations in any form.

The alkaloids concentrated in ashwagandha leaf and seeds are more pharmacologically active and at higher concentrations than those in the root; most commercial preparations use root extract. This distinction is occasionally lost in coverage that treats "ashwagandha" as a monolith.

Where this sits in the wider phytomedicine picture

What I find genuinely interesting about ashwagandha is the same thing I find interesting about many traditional botanical medicines: the historical use patterns often turn out to point at something real at the chemistry level, even when the clinical evidence hasn't caught up. The withanolides are a structurally distinctive class of compounds. The stress-axis research is biologically coherent. The plant deserves rigorous investigation.

But "deserves rigorous investigation" and "has proven effects" are different things. Right now, ashwagandha is one of the better-studied adaptogens; which still places it somewhere between "promising" and "established" on the evidence spectrum. That's worth stating plainly, particularly as it continues to appear in products positioned well beyond what the current trials support.

I keep going back to my nan's approach: she used plants with a humility about what she actually knew, versus what she'd heard. That seems like a reasonable model.

Sources

• Listed medicines evidence guidelines, Therapeutic Goods Administration (TGA)
• An investigation into the stress-relieving and pharmacological actions of an ashwagandha extract, Medicine via PubMed, NCBI
• Withania somnifera (ashwagandha); a systematic review of clinical trials, Journal of Ethnopharmacology via PubMed, NCBI
• Complementary medicines regulatory framework overview, Therapeutic Goods Administration (TGA)

, Naomi Ellison, Botanical & phytomedicine writer