Ayurvedic dravyaguna

Every substance is classified by six tastes and by what it does after digestion — and one branch of the tradition adds purified metals on purpose.

What it is

Dravyaguna — "substance and quality" — is the pharmacological branch of Ayurveda, the classical medical system of the Indian subcontinent.

A substance is characterised along five axes, and the last of them is the distinctive one:

Rasa — taste, of which six are recognised: sweet, sour, salty, pungent, bitter, astringent
Guṇa — quality, in paired opposites: heavy/light, hot/cold, oily/dry, and others
Vīrya — potency, essentially heating or cooling
Vipāka — the post-digestive effect, the taste a substance is held to resolve into after digestion, which may differ from its taste in the mouth
Prabhāva — specific action not predictable from any of the above; the tradition's own acknowledgement that some effects do not follow from its theory

Everything is organised around the three doṣas — vāta, pitta, kapha — and treatment aims at restoring their balance in a particular person rather than at a disease category.

Where it came from

The foundational texts are the Charaka Saṃhitā (internal medicine) and the Suśruta Saṃhitā (surgery), reaching their surviving form in the early centuries CE from older material, together with the later Aṣṭāṅga Hṛdayam of Vāgbhaṭa. The Charaka contains several hundred plant substances and a developed theory of how to reason about a new one.

Rasa śāstra is the alchemical branch, developed substantially from around the eighth century under tantric influence, which incorporates purified metals and minerals — mercury above all — into medicine. It is a genuine and continuous part of the tradition, and it is the source of the heavy-metal findings described below.

The colonial period nearly ended it. British administration progressively withdrew official recognition and funding through the nineteenth century, and Ayurveda survived as a village and household practice. Its twentieth-century revival was bound up with the independence movement, which is part of why it carries national as well as medical significance in India today. It is now regulated by a dedicated government ministry, AYUSH, and practitioners complete degree-length training.

How it is practised

By assessing an individual's constitution (prakṛti) and current imbalance (vikṛti), then prescribing — usually a compound formulation rather than a single herb, alongside diet, routine and sometimes the purification procedures of pañcakarma. Preparations include powders, medicated ghee and oils, fermented liquids and metal-containing bhasmas.

Described, not instructed. No formulations or doses appear here.

What we can and cannot say

We can say the theoretical structure is genuinely sophisticated. Vipāka — the idea that a substance's effect after digestion differs from its immediate quality — is an attempt to account for metabolism within a pre-chemical framework, and it is a more subtle move than anything in the Galenic system. Prabhāva, the explicit category for effects the theory cannot predict, is intellectually honest in a way that theoretical systems usually are not.

We can say a small number of its plants have real evidence. Boswellia serrata has trial support for osteoarthritis pain. Turmeric's curcumin is enormously studied — and the results are mostly disappointing for reasons that are well understood: oral curcumin is very poorly absorbed, and it is also a notorious assay-interference compound that produces false positives in laboratory screens. Ashwagandha has modest trial support for stress and sleep, and a growing number of liver injury case reports alongside it. Psyllium, from Plantago, is uncontroversial.

We can say the heavy metal issue must be stated plainly, and it is not simple. Robert Saper's studies in JAMA in 2004 and 2008 found detectable lead, mercury or arsenic in roughly one in five Ayurvedic products bought in Boston shops and online, and the highest concentrations were in rasa śāstra products.

This is not all contamination. In rasa śāstra the metals are added deliberately, on the doctrine that specific and elaborate purification procedures — śodhana, and calcination to bhasma — transform them into something therapeutic rather than toxic. Practitioners argue that properly prepared bhasmas are chemically distinct from the raw metal and that the products tested were improperly made. Some analytical work does find altered chemical forms. It also finds bioavailable lead. Cases of lead poisoning traced to Ayurvedic preparations are documented in the clinical literature in several countries, including in pregnancy, and Australian and US authorities have both issued warnings.

The honest position is that a real doctrinal claim is being made, that it has not been substantiated toxicologically, and that people have been poisoned.

And we can say the appropriation question is live inside the tradition. Turmeric, neem and basmati have all been the subject of patent disputes in which Indian institutions had to prove prior traditional use to overturn Western patents — the reason India built the Traditional Knowledge Digital Library, which now holds hundreds of thousands of formulations specifically as defensive prior art. The Western wellness market's adoption of Ayurvedic vocabulary generally returns nothing to the tradition it borrows from.

We cannot say whether the doṣa framework identifies anything real. What can be said is that it is a complete and internally coherent medical system with a genuine textual tradition, a small evidence base, an unresolved toxicological problem it does not accept as one, and a colonial history that explains a great deal about how it is defended.