# rasa-dhātu (रसधातु) > Canonical version of this page: https://nighantu.ageayurveda.com/lexicon/rasa-dhatu/ An Ayurvedic technical term, rendered into English in 7 different ways. The renderings do not agree, and the difference between them changes what the term is taken to mean. ## Identification | Field | Value | | --- | --- | | Transliteration | rasa-dhātu | | Devanagari | रसधातु | | Also written | rasa, rasadhatu, rasa dhatu, ahara rasa (distinct: see distinguishFrom) | | Category, as gathered | dhatu | | Grouped under | Body: tissues, wastes and channels | | Classical citations | 7 | | Citations checked | 2026-10-08 | ## How it is translated, and whether the translation holds Each rendering is given with the source that uses it. The assessment is ours. ### Primary circulating nutrient fluid, primary product of digestion WHO International Standard Terminologies on Ayurveda · ITA-2.2.4 (Sanskrit: rasa-dhātuḥ, rasaḥ) · standard WHO's headword is a two-part descriptive phrase rather than a single English word, which is itself evidence that no single word works. Notably avoids 'plasma', 'lymph' and 'chyle'. Reproduced unaltered and attributed from the WHO International Standard Terminologies on Ayurveda, which is what that licence permits, and deliberately absent from the downloadable dataset, which is CC BY 4.0. ### lymph chyle Sushruta Samhita, tr. Kunja Lal Bhishagratna (1907-1916) · Sutrasthana XIV and XV, passim · translation Bhishagratna's standing rendering, and a period artefact: it fuses two distinct nineteenth-century physiological categories (lymph, chyle) into a compound that is not a term of art in English at all. He also uses bare 'chyle' and 'the Rasa'. ### juice Charaka Samhita, tr. Avinash Chandra Kaviratna (1896-1913) · Chikitsasthana XV; Sutrasthana XXVIII · translation Kaviratna's usual rendering, often as "'Rasa' (juice)". He also uses 'the fluids' for the same member of the dhātu list, and 'food-substance' for āhāraprasāda. ### the fluids Charaka Samhita, tr. Avinash Chandra Kaviratna (1896-1913) · Sutrasthana XXVIII, in the eight-member enumeration · translation Same word, different English, three pages from the previous rendering. ### plasma Common modern Ayurvedic teaching and clinical literature · textbook · our paraphrase of the source, not its words The commonest modern equation. It is an equation, not a translation, and it is contested: the classical rasa is said to be diffused everywhere by vyāna vāyu and to yield breast milk and menstrual blood, neither of which plasma does. ### lymph Wikipedia, Dhātu (ayurveda) · article body, list of seven dhatus · encyclopaedia Recorded as a fact about a widely-read source. A third distinct biomedical equation for the same term, incompatible with 'plasma'. ### nutrient fluid / nutritional fluid Journal usage, e.g. PMID 42161239 and related JAIM papers · journal · our paraphrase of the source, not its words The rendering that has drifted into the indexed literature, closest to WHO's. ## The classical passages ### Sushruta Samhita (Sanskrit mula) Sutrasthana 14:13, checked against the source > तत्र 'रस' गतौ धातुः, अहरहर्गच्छतीत्यतो रसः ॥१३॥ Sanskrit mūla · https://www.siva.sh/sushruta-samhita/sutra-sthana/14/13 The text's own etymology: rasa from the root ras/gati, 'to go', because it goes constantly. Note the word dhātu is used here in its GRAMMATICAL sense (verbal root), in the same chapter that defines the bodily dhātu. ### Sushruta Samhita Sutrasthana 14:corresponds to mula verse 13, checked against the source > The term Rasa is derived from the root "Ras", to go, and the substance is so called from the fact of its continually flowing through and permeating every vital principle of an animated organism. tr. Kunja Lal Bhishagratna (1907-1916) · https://archive.org/stream/b24758619_0001/b24758619_0001_djvu.txt The quotable English of the etymology. Constant motion and pervasion, not a compartment, is what the name asserts - which is the strongest textual argument against equating rasa with any single named fluid. ### Sushruta Samhita Sutrasthana 14:prose opening of the chapter, checked against the source > The food is fully digested with the help of the internal heat and ultimately assimilated in the system, giving rise to lymph chyle (Rasa) which is extremely thin or attenuated in its consistency and which forms the essence of the assimilated food. tr. Kunja Lal Bhishagratna (1907-1916) · https://archive.org/stream/b24758619_0001/b24758619_0001_djvu.txt Rasa as the immediate product of digestion, defined by fineness of consistency. ### Sushruta Samhita Sutrasthana 14:prose section, checked against the source > The lymph chyle (Rasa), though running through the whole organism, has its primary seat in the heart, whence it flows through the twenty-four vessels which branch off from the latter (heart) to the remotest parts and extremities of the body. Of the aforesaid twenty-four vessels, ten are up-coursing, ten are down-coursing, and four have a lateral direction. tr. Kunja Lal Bhishagratna (1907-1916) · https://archive.org/stream/b24758619_0001/b24758619_0001_djvu.txt Rasa's seat in the heart and its distribution through twenty-four named vessels - the passage most often cited in support of a circulatory reading. ### Sushruta Samhita Sutrasthana 14:prose section, checked against the source > since the Rasa or lymph chyle is a fluid, and possessed of lubricating, vitalising, moistening, and nutritive (lit :- supporting) properties, it must be included within the class of Saumya (cooling) substances. The Rasa, though a Saumya fluid, obtains its characteristic pigment (Ragam) in its passage through the spleen and liver. tr. Kunja Lal Bhishagratna (1907-1916) · https://archive.org/stream/b24758619_0001/b24758619_0001_djvu.txt Rasa's qualities as saumya, and the mechanism by which it becomes rakta - colouring in spleen and liver. This is the join between rasa and rakta and is stated in Sushruta but not in the Charaka passages retrieved here. ### Sushruta Samhita (Sanskrit mula) Sutrasthana 14:14, checked against the source > स खलु त्रीणि त्रीणि कलासहस्राणि पञ्चदश च कला एकैकस्मिन् धाताववतिष्ठते; एवं मासेन रसः शुक्रं स्त्रीणां चार्तवं भवति ॥१४॥ Sanskrit mūla · https://www.siva.sh/sushruta-samhita/sutra-sthana/14/14 3,015 kalas per dhātu, hence one month from rasa to shukra. Verified Sanskrit with verse number. ### Charaka Samhita Chikitsasthana 15:35 in Kaviratna's marginal numbering, checked against the source > The 'dhatu' called 'Rasa' (that is, the juicy matter into which food is first converted) is continuously diffused through every part of the body simultaneously, by the life-breath called 'Vyana' whose function it is to diffuse. tr. Avinash Chandra Kaviratna (1896-1913) · https://archive.org/stream/BIUSante_47357/BIUSante_47357_djvu.txt Simultaneous whole-body diffusion of rasa by vyāna vāyu. Sits in tension with the strictly serial reading of the dhātu chain, and is the textual basis for the later eka-kāla dhātu poṣaṇa model. ## Not to be confused with - **āhāra rasa.** The nutrient essence coming out of digestion, before it has become the rasa dhātu proper. Bhishagratna's footnote to Su.Su.14 distinguishes 'the immature Rasa, or the Rasa in its nascent stage' from the matured bodily rasa it then enters. Modern writing frequently collapses the two. - **rasa (taste).** The six tastes. Entirely different technical sense of the same word, and the commoner one in the dietetics and dravyaguna chapters. Charaka's Vimanasthana opens with Rasa-vimana, which is about taste, not tissue. - **rasa (mercury / Rasashastra).** In the pharmaceutical literature rasa means mercury and by extension the whole metallurgical branch. Yet another collision on the same lemma. - **rakta.** The next dhātu. Sushruta makes rasa become rakta by acquiring colour in spleen and liver, so the two are stages of one material in the source, which is exactly why translating rasa as 'plasma' and rakta as 'blood' misrepresents the relation: plasma is a component of blood, not its precursor. - **lasika.** Usually taken as the lymph proper in Ayurvedic anatomy. If rasa is translated 'lymph', lasika has nowhere to go. - **ojas.** Ojas is the sāra of all seven dhātus, not the first of them, though Bhishagratna's chapter-XV rendering ('The quintessence of all the fundamental principles of the body, starting with lymph chyle and ending with semen, is called the Ojas') makes clear it is derived from the whole chain including rasa. ## Renderings that do not hold - plasma. An equation dressed as a translation. Plasma is a fraction of blood; classical rasa is the precursor of blood, is said to be distributed simultaneously to the whole body by vyāna vāyu, and yields breast milk and menstrual blood. No retrieved source establishes the equation; it is asserted in teaching. - lymph. Incompatible with 'plasma', yet both circulate widely, including in Wikipedia's dhātu article, which uses 'lymph'. Also strands lasika, which is the term lymph usually translates. - chyle / lymph chyle. Bhishagratna's rendering, and a Victorian physiological category. 'Lymph chyle' is not an English medical term at all. Quotable as a period document, not usable as a gloss. - serum. Occasionally seen. Serum is plasma minus clotting factors, a still narrower biomedical fraction, and nothing in the retrieved sources supports it. - sap / essence. Loses the fact that rasa is a defined bodily constituent with a seat, a set of vessels, a timetable and named products. ## Open questions Recorded rather than resolved. - Whether the sources intend rasa as a single substance or a class of circulating fluids is not resolved by anything retrieved. The etymology (that which goes) supports the second reading; the anatomical passage (seat in the heart, twenty-four vessels) supports the first. - No retrieved study measures anything and calls it rasa. There is no operational definition of rasa dhātu in the peer-reviewed literature, and PubMed searches for 'rasa dhatu' (12 hits) and 'rasa dhatu plasma' (0 hits) return no study that attempts one. - The relation between rasa and lasika is not addressed in the passages retrieved and needs a targeted search of Sushruta Sharirasthana. - Charaka's simultaneous-diffusion statement (Ci.15.35) and Sushruta's five-days-per-dhātu timetable (Su.Su.14.14) cannot both describe the same process straightforwardly; no retrieved source reconciles them. ## Citation Age Ayurveda Nighantu, "rasa-dhātu", https://nighantu.ageayurveda.com/lexicon/rasa-dhatu/, CC BY 4.0. Whole lexicon: https://nighantu.ageayurveda.com/lexicon.json and https://nighantu.ageayurveda.com/lexicon.csv. Educational reference only. A term entry explains what a word means and how it has been translated. Nothing here is advice.