Kala-parinama (time, season and ripening as causes of disease)
How much weight this concept bears. Separate the premise from the doctrine, because the record previously did not. THE PREMISE. That human physiology varies with season and with time of day is supported by work outside Ayurveda. Dopico and colleagues 2015 (PMID 25965853) found seasonal expression in peripheral blood mononuclear cells and in adipose tissue across several cohorts, and Wucher and colleagues 2023 (PMID 36745672) found day-night and seasonal expression differences across many tissues in a different design. That is the limit of what those papers do for this record. THE DOCTRINE. Kala-parinama is not the claim that physiology varies with time. It is the claim that time-transformation is one of three general causes of disease, operating through season-specific dosha accumulation, aggravation and subsidence, and correctable by season-specific regimen. Neither Dopico nor Wucher measured a dosha, tested the six-ritu partition, tested the morning-noon-evening kapha-pitta-vata sequence, or evaluated any ritucharya prescription. Citing them in support of the doctrine would be borrowing the credibility of a literature that never tested it, and the earlier version of this paragraph did exactly that: it said the premise was 'independently and robustly established' and then let that sentence stand as the evidential footing for the whole category. It is not. A separate inference has to be blocked too. Several conditions have well-documented seasonal incidence, including cardiovascular events, respiratory infection and affective disorder. Establishing that a disease is seasonal does not establish the mechanism the texts assign to it. A seasonal incidence curve is consistent with the classical dosha assignment, with pathogen ecology, with indoor crowding, with vitamin D, with temperature effects on vascular tone, and with several other accounts at once, and it discriminates between none of them. The record makes no claim that any seasonal disease pattern supports the dosha-seasonal mechanism. WHAT THE PREMISE ITSELF WILL NOT CARRY. 'Robustly established' was also too strong for the seasonal-transcriptomics result taken on its own terms, and the strongest objection is in the primary paper. Dopico and colleagues state in their own abstract that the seasonal change in blood cell composition 'could explain the gene expression periodicity', and in their discussion that the PBMC transcriptional landscapes 'appear to be predominantly driven by annual changes in the cellular composition of blood'. On the authors' own reading, much of the headline signal is a shift in which cells are in the sample rather than a seasonal programme inside a given cell. They also report fewer seasonal genes and a less similar seasonal pattern in their Icelandic donors, and write that 'the impact of living at higher latitudes requires further exploration'. So the premise is supported, and it is supported with live internal caveats about cell composition and about latitude. Wucher and colleagues 2023 is a useful second design because it works from postmortem tissue rather than from circulating PBMCs, and so is not exposed to the same blood-composition confound; it is exposed to others, which its entry records. THE DOCTRINE'S OWN EVIDENCE. On the specific content of kala-parinama, the searches run for this record (described in gatheringNotes) located two narrative reviews, one ethnographic study, one small cross-sectional study of season and constitution against lipids, one randomised open-label trial of a ritucharya-derived intervention (PMID 33935439), one registered single-arm protocol for seasonal purification with no results yet (PMID 42748372), and one cross-sectional survey bearing on the daily-time limb (PMID 42519781). On that set: the one randomised trial tests a single seasonal adjuvant in one season in one region against no-treatment control, open-label, n=60, with disease-frequency and quality-of-life endpoints, which is evidence about that preparation in that setting and not about the six-ritu scheme, the dosha-seasonal mechanism, or ritucharya as a system. The protocol paper is a protocol: single-arm, no control, explicitly 'hypothesis-generating'. The record does not claim that this is the whole literature. It is what the searches named in gatheringNotes returned, and a bounded search cannot support a statement that nothing else exists. What the record does claim is that it located nothing that tests the dosha-seasonal mechanism itself, and the specific gaps are itemised in notKnown rather than summarised away here. A LAST POINT ABOUT THE CATEGORY. Within the classical scheme, time absorbs both the genuinely periodic (intermittent fevers, seasonal illness) and the residual (idiopathic disease, ageing, death), so the category does explanatory work as a default attribution as well as a causal one, and the two uses are not separated in the sources. That is a structural observation about the texts, not an evidential claim, and it is the one thing in this paragraph that does not depend on the modern literature at all.
Kala-parinama is the Ayurvedic category for disease caused by time. It covers three distinguishable things that the texts run together: the seasonal cycle and its abnormalities, the internal clock of the day, night and digestive phases, and the irreversible ripening of the organism into old age and death. Charaka names time as one of the three general causes of disease and states that its pathological forms are the same three as for any other cause, namely deficiency, excess and perversity of the expected seasonal character. In the epidemic chapter Charaka ranks time as the most potent of the four collective vitiating factors, on the practical ground that a person can leave a place or avoid a water source but cannot step out of the season. Sushruta gives time its own disease class, kala-bala-pravritta, subdivided according to whether the season behaves naturally or contrarily. Charaka also treats the effects of pure ripening, decrepitude and death, as a subclass that has no remedy.
| Subject area | How disease is held to arise |
|---|---|
| Domain, as recorded | etiology |
| Contested questions | 4 |
| Stated as not known | 13 |
| Classical citations | 11, 10 quoting the text |
| Research papers assessed | 9 |
| Citations checked | 2026-10-08 |
What is contested, and by whom
These are the questions on which the sources genuinely disagree. Each position is given as its source states it. No position is presented as the settled answer, because none of them is.
Which mechanism does time act by?
This is contested.
- Charaka Sutra 6 gives a physical mechanism: solar desiccation and lunar or rain-driven moistening acting on the whole environment and thence on the body.
- Charaka Vimana 3 gives an astral and moral mechanism: perverse conditions of constellations, planets, sun, moon and wind, rooted ultimately in collective adharma.
- Sushruta Sutra 24 gives a narrowly meteorological mechanism: variation of atmospheric heat and humidity, with no astral or moral element.
- These are not reconciled in the sources, and modern Ayurvedic writing usually silently adopts the Sushruta version.
Is ageing and death a disease category or an exclusion from it?
This is contested.
- Charaka Sharira 1.122 says decrepitude and death come naturally and that what nature brings about has no remedy, which excludes them from therapeutics.
- Sushruta Sutra 24 classes them as a disease type, svabhava-bala-pravritta, and then splits them into timely and untimely, which makes the untimely form modifiable by conduct.
- The rasayana literature elsewhere in Charaka treats ageing as at least partly modifiable, which sits uneasily with Sharira 1.122.
Is time a coordinate cause or the dominant one?
This is contested.
- Sutra 11.43 presents the three general causes symmetrically.
- Vimana 3.13 ranks time above place, water and air, but the argument given is unavoidability of exposure rather than strength of effect, which is a different claim.
- Sharira 1 subordinates time to prajnaparadha by making faults of the understanding the root of the epidemic chain.
How many seasons, and whose calendar?
This is contested.
- The six-ritu scheme is tied to a north Indian lunisolar calendar with a monsoon.
- The same scheme is applied without adjustment in temperate, equatorial and southern-hemisphere settings in contemporary practice and in the reviews, with no discussion of whether the mapping survives transplantation.
- Sushruta's criterion, natural versus contrary seasonal features, is calendar-independent in principle but is not operationalised anywhere.
What is not known
Stated rather than left out. Where a negative has actually been searched for rather than assumed, the entry says so.
- Whether any measured human rhythm corresponds to the classical morning-kapha, noon-pitta, evening-vata clock. The searches named in gatheringNotes located no study testing this against actigraphy, cortisol, core temperature, melatonin or any other established circadian marker. The nearest located work, PMID 42519781, asks shift workers to report their own digestive state and measures no circadian marker, so it does not close this gap. Reworded in the 2026-10-06 revision: the earlier version asserted that no study had tested it, which a bounded search cannot support.
- Whether seasonal dosha accumulation and aggravation, the chaya-prakopa-prashama cycle, predicts anything about symptom onset in a prospective cohort.
- Whether following a ritucharya regimen as a system changes any clinical outcome. One randomised trial of a single ritucharya-derived preparation was located, PMID 33935439, and it is open-label, n=60, one season, one region, with no season-mismatched comparison arm, so it tests the preparation and not the seasonal principle. One registered seasonal-purification study was located, PMID 42748372, and it is a single-arm protocol with no results and no off-season comparison. Corrected in the 2026-10-06 revision: the earlier version asserted that no randomised trial existed, which was an exhaustiveness claim and was also false.
- How ritucharya is to be adapted, if at all, outside the monsoon-calendar regions the texts were written for.
- Whether the classical criteria for a vitiated season, deficient, excessive or contrary seasonal character, can be applied by independent observers with any agreement, or against meteorological data.
- Whether the well-documented seasonality of specific conditions (cardiovascular events, respiratory infection, affective disorder) has any relationship to the classical seasonal disease assignments beyond coincidence.
- Where the boundary lies between time as a genuine cause and time as the residual category for disease with no identified cause, given that Sharira 1.122 assigns both to it.
- Whether the untimely form of the svabhava-bala class, that is premature ageing from unhealthy living, is distinguishable in practice from ordinary accumulated risk-factor exposure.
- Whether the seasonal-transcriptomics result survives adjustment for blood cell composition. The authors of PMID 25965853 state that composition changes 'could explain the gene expression periodicity' and that their PBMC signal 'appear[s] to be predominantly driven' by them, and call for work in purified immune cell subsets. The record located no such follow-up in purified subsets. Added in the 2026-10-06 revision, because the record previously carried the premise without this caveat.
- Whether any independent reanalysis or formal methodological critique of the human seasonal-transcriptomics literature has been published. The searches run (PubMed, terms combining seasonal and transcriptome or gene expression with deconvolution, cell composition, confounding and reanalysis) returned no such paper, and the strongest objections the record can cite are therefore the primary authors' own. This is a gap in the record's coverage and is stated as one rather than filled with a general remark; it is not a claim that no critique exists.
- What the registered seasonal-regimen and seasonal-Panchakarma trial landscape actually contains. The Clinical Trials Registry-India was not searched directly for this record: no public API or bulk export was located and its search interface is form-driven. The two registered interventions cited here, PMID 33935439 and PMID 42748372, were reached through PubMed, which indexes only registered trials that have also been published. PMID 35370375 describes CTRI's Ayurveda holdings in general but does not enumerate seasonal-regimen trials. So the number, design and results status of registered-but-unpublished ritucharya and seasonal-purification trials is unknown to this record.
- Whether the specific mainstream literatures adjacent to this concept bear on it at all, because the record has not surveyed them. Chronobiology, chronotherapy and chronopharmacology, and the epidemiology of seasonal disease onset are each large fields. The modern section here is a purposive selection chosen against the record's own classical claims, not a survey, and it should not be read as a representative sample of any of those fields. Added in the 2026-10-06 revision in response to the thinness finding; see stillOpen for why this is declared rather than remedied.
- Whether seasonal purification as practised, that is Vamana in vasanta and Virechana in sharad, has any effect distinguishable from the acute effects of emesis, purgation, oleation, fomentation and the controlled post-procedure diet. The one registered study located, PMID 42748372, is single-arm by design and so cannot make that distinction, and it has not reported.
The terms this concept is built from
Each is a technical term in its own right. Where this site holds a lexicon entry for one, it is linked.
| Term | What it names |
|---|---|
| ritu | The six seasons of the Indian year: hemanta, shishira, vasanta, grishma, varsha, sharad |
| ayana | The two solar half-years, adana-kala (the taking period, northward course, drying and weakening) and visarga-kala (the giving period, southward course, moistening and strengthening) |
| ritu-vaishamya | Seasonal abnormality in the same three modes as any other cause: ayoga (the season's character deficient), atiyoga (excessive), mithyayoga (perverse, showing another season's character) |
| dosha-kala | The recurring daily and prandial clock: kapha in the morning, pitta at noon, vata in the evening, with the same sequence across night watches and across the phases of eating, digesting and post-digestion |
| vyadhi-kala | Time in respect of the accession of a specific disease, including the periodicity of intermittent fevers at one, two, three and four day intervals |
| jara and mrityu | Decrepitude and death as the pure ripening of time, which Charaka says arrive naturally and admit of no remedy |
| parinama | Literally ripening or transformation; Charaka states explicitly that this is another name for kala in the etiological triad |
| kala-bala-pravritta | Sushruta's dedicated disease class for time-caused illness, subdivided by whether the season exhibits natural or contrary features |
The classical passages
Each citation gives its address so a reader can check it in a printed edition, our account of what it establishes, and the result of reading it against its source.
Charaka Samhita, Sutra Sthana, Lesson XI (Tistraishaniya), verse 42 in Kaviratna's numberingSutra Sthana 11:42 (Kaviratna) · checked against the source
Heat, cold, and rain, or autumn, summer, and rain, constitute the indications of the year. That is also called Time. When the particular indication of a particular period of Time manifests itself in excess, that is called excess of correlation in respect of Time (as excess of cold in winter, or excess of heat in summer, or excess of rain in the rainy season). When such indication manifests itself in a measure less than normal, that is called want or absence of correlation (such as want of cold in winter or of heat in summer). When indications, that are the reverse of those which are normal, are manifested, that is called improper correlation (such as heat in winter or cold in summer). ... Thus are the three subjects treated of, viz., the improper contact of objects of sense with the Mind, faults of the Understanding, and Time or Parinama.
The operational definition of pathological time as ayoga, atiyoga and mithyayoga of the season's expected character, and the explicit identification of kala with parinama.
Charaka Samhita, Sutra Sthana, Lesson XI, verse 43 in Kaviratna's numberingSutra Sthana 11:43 (Kaviratna) · checked against the source
These three, (viz., the improper contact of objects of sense with the Mind, faults of the Understanding, and Time,) each sub-divided into three kinds, constitute the causes of disease. Connection therewith in normal or judicious proportions is the cause of health.
The three-by-three structure of the general etiology, and that time in judicious proportion is a cause of health rather than a neutral background.
Charaka Samhita, Sutra Sthana, Lesson VI (Tasyashitiya), verse 1 in Kaviratna's numberingSutra Sthana 6:1 (Kaviratna) · checked against the source
Of him who is acquainted with the opportuneness of conduct and food with seasons, strength and complexion (and happiness and period of life) increase, in consequence of his food, etc., (being taken with propriety).
The premise of ritucharya: matching conduct and diet to season is presented as a determinant of strength, complexion and lifespan.
Charaka Samhita, Sutra Sthana, Lesson VI, verses 2-5 in Kaviratna's numberingSutra Sthana 6:2-5 (Kaviratna) · checked against the source
For the purposes of this lesson, the year should be known as consisting of six portions, divided according to the seasons. Of these, the three seasons commencing with the season of dews and ending with summer constitute the period when the Sun travels in the region lying to the north of the equinoctial. That is again the period when the Sun takes (i.e., sucks up the liquid portion of every earthly object). The three other seasons commencing with the season of rains and ending with Hemanta constitutes the period of the Sun's southerly course. That is, besides, the time when the Sun gives (or yields moisture to all earthly objects). ... In the period of Taking, the Sun, by means of his rays, sucks up the moisture of the universe; and keen and rough winds also dry up the same.
The adana/visarga half-year scheme and its stated mechanism, solar and wind-driven desiccation versus lunar and rain-driven moistening, which is the physical model underlying the seasonal dosha cycle.
Charaka Samhita, Sharira Sthana, Lesson I, verses 117-120 in Kaviratna's numberingSharira Sthana 1:117-120 (Kaviratna) · checked against the source
In the Lesson on the causes, in brief, of diseases, time in respect of the accession of disease has been explained. This includes the topics, as previously explained, of the accession, excitement, and alleviation of bile and the rest, the seasons ending with the rainy, marked by characteristics that are false, excessive, or attenuated, as causes of diseases; rules about timeliness and untimeliness in respect of food eaten or in course of digestion or after digestion; forenoon, noon, and afternoon, and the three divisions, called yamas, of the night; particular diseases which spring up in particular times laid down; fevers which appear on every alternate day; those which appear with intervals of two days between successive paroxysms; and those which appear with intervals of three or four days between successive paroxysms.
The full scope of kala-samprapti: it spans seasonal, circadian, prandial and disease-periodicity time in a single category. The intermittent-fever periodicities are the one component with an obvious external referent (malarial tertian and quartan patterns).
Charaka Samhita, Sharira Sthana, Lesson I, verse 122 in Kaviratna's numberingSharira Sthana 1:122 (Kaviratna) · checked against the source
With the development of Time, decrepitude, death and such diseases as are not due to known and defined causes, are seen to come naturally. That which is brought about by Nature has no remedy.
That svabhava-bala time effects, ageing and death, are explicitly placed outside therapeutics. Also that idiopathic disease is assigned to time by default.
Charaka Samhita, Vimana Sthana, Lesson III (Janapadoddhvamsaniya), verse 9 in Kaviratna's numberingVimana Sthana 3:9 (Kaviratna) · checked against the source
As regards Time, that should be known as baneful which discovers symptoms contrary to those which properly belong to the season (that is running), or symptoms that are aggravated or attenuated in comparison thereto.
The diagnostic criterion for vitiated time at population scale, stated in the same three modes as at Sutra 11.
Charaka Samhita, Vimana Sthana, Lesson III, verses 12-13 in Kaviratna's numberingVimana Sthana 3:12-13 (Kaviratna) · checked against the source
Among these four, viz., Place, Time, Atmosphere, and Water, when they have all become perverted, explanations are subjoined as to which is more potent than which and for what reasons. Guided by the consideration of unavoidability, one conversant with the topic should hold that Water is a more potent cause than Air; Place a more potent cause than Water; and Time a more potent cause than Place, by nature.
That time is ranked the most potent of the four collective vitiating factors, and the explicit reason given, unavoidability, which is an argument about exposure rather than about mechanism.
Sushruta Samhita, Sutra Sthana, Chapter XXIV (Vyadhi-samuddeshiya)Sutra Sthana 24:not numbered in Bhishagratna's rendering of this passage · checked against the source
The Periodical type (Kala-vala-pravritta) includes diseases that are brought about by the variation of atmospheric heat or humidity with the change of the seasons, and admits of being grouped under two different sub-heads, according as the seasons, which usher these changes in, exhibit natural or contrary features.
Sushruta's independent disease class for time, with a narrower and more physical mechanism than Charaka's, namely variation of atmospheric heat and humidity.
Sushruta Samhita, Sutra Sthana, Chapter XXIV, on the svabhava-bala-pravritta classSutra Sthana 24 · checked against the source
The Natural or the Spontaneous (Svabhava-vala-pravritta) type includes such natural organic phenomena as, decrepitude, death, hunger, thirst, sleep, etc. These phenomena are either Kalakrita (timely) or Akalakrita (untimely). They are called Kalakrita when they occur at the proper time in persons who strictly observe the rules of health, and Akalakrita, when they appear at the improper time (morbid or premature) as the effects of unhealthy living.
The timely/untimely distinction, which is the closest classical approach to a premature-ageing concept and the point at which the otherwise fatalistic time category becomes modifiable by conduct.
Charak Samhita New Edition (carakasamhitaonline.com), entry 'Kala'
Standard-numbering locations for the same doctrine: kala as a fundamental padartha at Sutra 1/48-49, kala in clinical examination at Sutra 1/52, seasonal qualities at Sutra 6/3, parinama at Sutra 11/42 and Vimana 8/48, kala as etiological factor at Sutra 11/43 and Sutra 25/25. Located, not quoted.
What the research actually shows
Every paper located for this concept, with what it measured and what it does and does not establish. The assessment is ours.
Widespread seasonal gene expression reveals annual differences in human immunity and physiology. · Nat Commun · 2015 · PMID 25965853
Seasonal expression in human peripheral blood mononuclear cells and adipose tissue, in several cohorts. Quoted from the paper: 'Here we find more than 4,000 protein-coding mRNAs in white blood cells and adipose tissue to have seasonal expression profiles, with inverted patterns observed between Europe and Oceania.' The headline proportion belongs to one cohort, not to humans generally: 'Strikingly, we found ~23% of the genome (5,136 unique genes out of 22,822 genes tested) to show significant seasonal differences in expression in the BABYDIET data set.' The hemisphere inversion was seen in asthmatic PBMC samples: 'Summer and winter BABYDIET genes maintained their seasonal expression patterns in the asthmatic PBMC samples, with their patterns inverted in Australia.' The authors also report seasonal change in blood cell counts, and state in the abstract that these changes 'could explain the gene expression periodicity'. In the Gambian cohort the seasonal finding reported is in cell numbers, not in the transcriptome: 'In this data set, seasonal peaks in cell numbers correlated with the rainy season (June to October), during which time the infectious disease burden is at its highest levels.'
How much it shows. Corrected in the 2026-10-06 revision. Large samples, multiple cohorts, major journal, and the design is sound for its own question. Three things the earlier version of this entry got wrong or left out. First, it said 'roughly a quarter of the human genome shows seasonal expression' as a general result; the ~23% figure is from the BABYDIET cohort alone and is a proportion of the 22,822 genes tested, not of the genome. Second, it described 'a rainy-season-aligned pattern in a Gambian cohort' as if the Gambian result were transcriptomic; the Gambian result reported is seasonal variation in blood cell counts. The hemisphere inversion is Europe versus Australia. Third, and most important, it mentioned seasonal variation in cell composition as an additional observation rather than as the confound the authors themselves identify. The authors write that the PBMC transcriptional landscapes 'appear to be predominantly driven by annual changes in the cellular composition of blood', and that 'although our data suggest that cell-type numbers contribute the majority of seasonal gene expression in PBMCs, future studies of seasonal phenotypic differences within purified immune cell subsets are likely to reveal an additional layer of complexity in the human immune system'. They further note the latitude limit: 'Fewer seasonal genes were identified in Icelandic donors, and common seasonal genes had a less similar seasonal pattern in this data set. If a seasonal photoperiodic clock exists in humans, the impact of living at higher latitudes requires further exploration.' Caveat for honest use, restated and strengthened: this study establishes that season tracks measurable differences in human blood and adipose tissue, and on the authors' reading much of that is cell-composition shift. It says nothing whatever about doshas, about the six-season scheme, or about ritucharya prescriptions. It supports the general premise of kala-parinama and none of its specific content. Included deliberately as an outside comparator, not as Ayurvedic evidence.
Impact of season and constitution on lipid parameters. · Ayu · 2013 · PMID 24049409
In 54 healthy volunteers, lipid profile values were reported as higher in winter, and higher in kapha and pitta prakriti participants during winter.
How much it shows. Weak. Very small single-centre observational study, no control for diet, physical activity or body mass, prakriti assignment by unvalidated method with no reported inter-rater agreement, multiple comparisons unaddressed, conclusions about cardiovascular risk drawn from a single cross-sectional lipid measurement. Of the studies the searches named in gatheringNotes returned, this is the strongest located that is directly on the season-and-constitution claim, which is itself the finding. Reworded in the 2026-10-06 revision: the earlier phrasing said it was close to the strongest that exists, which a bounded search cannot establish.
Ritucharya: Answer to the lifestyle disorders. · Ayu · 2011 · PMID 22661838
Compiles the classical ritucharya prescriptions and argues they address modern lifestyle disorders.
How much it shows. Narrative review, explicitly so. No systematic search, no data, no outcome. Widely cited within the Ayurvedic literature, which inflates its apparent authority.
Understanding COVID - 19 pandemic - A comprehensive Ayurvedic perspective. · J Ayurveda Integr Med · 2022 · PMID 33262017
Applies the janapadodhvamsa framework, in which time is the most potent vitiating factor, to COVID-19, and proposes staged management.
How much it shows. Narrative conceptual paper. Proposes a mapping and a treatment scheme without testing either. Useful as evidence of how the kala doctrine is deployed in practice, not as evidence that the doctrine is correct.
Patient Assessment and Chronic Pain Self-Management in Ethnomedicine: Seasonal and Ecosystemic Embodiment in Ayurvedic Patient-Centered Care. · Int J Environ Res Public Health · 2020 · PMID 32326150
Ethnographic description of how seasonal and ecological reasoning actually enters Ayurvedic clinical encounters in chronic pain care.
How much it shows. Qualitative study, appropriate methods for its question, no claim of efficacy. Valuable because it documents the clinical use of kala reasoning rather than asserting its validity.
Day-night and seasonal variation of human gene expression across tissues. · PLoS Biol · 2023 · PMID 36745672
Day-night and seasonal transcriptomic variation across many human tissues, in a design independent of circulating-PBMC sampling. From the abstract: 'We used the time and season of death of 932 individuals from GTEx to jointly investigate transcriptomic changes associated with those cycles across multiple tissues. Overall, most variation across tissues during day-night and among seasons was unique to each cycle. Although all tissues remodeled their transcriptomes, brain and gonadal tissues exhibited the highest seasonality, whereas those in the thoracic cavity showed stronger day-night regulation.' And: 'Seasonal variation of expression affected multiple pathways, and it was enriched among genes associated with the immune response, consistent with the seasonality of viral infections.'
How much it shows. Added in the 2026-10-06 revision, as the counterweight the record previously lacked on the premise side. Large, peer-reviewed, open access, and methodologically distinct from Dopico 2015: it reads postmortem tissue from GTEx rather than circulating PBMCs, so it is not exposed to the blood cell-composition confound that the Dopico authors say drives most of their signal. That independence is the reason it is here. It is exposed to confounds of its own, which the paper's design makes unavoidable: season and hour of death are not randomly assigned, they correlate with cause of death, with agonal state and with postmortem interval, and the inference runs from time of death to tissue expression rather than from a sampled living rhythm. That reading of the design is the gatherer's, not a statement the authors make. What it does for this record is narrow and should not be stretched: it strengthens the premise that both the daily and the annual cycle leave a measurable trace in human tissue, and it reports that the two cycles are largely distinct from each other, which is at least structurally interesting against a doctrine that runs the same kapha-pitta-vata sequence through the day, the night and the year. It does not measure a dosha, does not test the six-ritu partition, does not test the morning-noon-evening assignment, and contains no Ayurvedic content of any kind.
Efficacy of Rituharitaki (seasonal adjuvant of Haritaki) on disorders of Varsha Ritu (monsoon) w.s.r. to quality of life: An open labelled randomized controlled clinical trial. · Ayu · 2019 · PMID 33935439
A randomised controlled trial of a ritucharya-derived intervention, which the record previously said did not exist. From the abstract: 'Administration of Haritaki with suitable vehicle as per season (Rituharitaki) is a simple, cost-effective preventive measure which can be used for such conditions.' Method: 'From 82 participants, based on inclusion criteria, 60 participants were selected and randomly allocated into trial and control group of 30 each using a computer generated random number table. Intervention given was Rituharitaki (Terminalia chebula Retz) in tablet form-3 tablets of 1g each and Saindhava (rock salt) 1g with lukewarm water at 6.30 am on empty stomach to the participants of trial group for 60 days in Varsha Ritu in Kerala.' Result: 'Significant results were obtained in the trial group in reducing the severity and frequency of common cold (p < 0.001), cough (p < 0.05), and fever (p < 0.001).'
How much it shows. Added in the 2026-10-06 revision because the record's own notKnown asserted that no randomised trial of ritucharya existed, which was both an exhaustiveness claim a bounded search cannot support and, as it turns out, false. The trial is real and it is randomised. It is also weak on the points that matter most for the doctrine. It is open-label, so every symptom endpoint is unblinded self-report against an untreated control, which is the design most vulnerable to expectation effects; n=60 in one centre in one season in one region; no placebo; the primary endpoints are symptom frequency and severity plus WHOQOL-BREF domains, with haematological parameters reported alongside and no stated correction for the number of comparisons made. What it tests is one preparation given at one time of year. It does not test the six-ritu partition, does not measure dosha accumulation or subsidence, and does not compare season-matched against season-mismatched administration, which is the comparison that would actually test the ritucharya principle rather than the drug. A positive result here is consistent with Haritaki having an effect in any season. It is cited to replace a false negative claim with a located positive study and its limits, not as support for the doctrine.
Evaluation of Vamana and Virechana as Interventions to Decelerate the Aging Process in Healthy Adult Volunteers: Protocol for an Exploratory Single-Arm Clinical Trial. · JMIR Res Protoc · 2026 · PMID 42748372
A CTRI-registered seasonal-purification intervention study aimed at the ageing limb of kala-parinama, published as a protocol. From the abstract: 'Ritu sodhana (seasonal purification) imparts rejuvenation in healthy individuals. However, its efficacy for health span and decelerating the aging process in healthy individuals remains a gray area.' Registration and design: 'The study was prospectively registered in the Clinical Trial Registry-India (CTRI; CTRI/2024/02/062176), uses a pre-posttest study design, and includes 53 participants 35 years to 65 years old. The study is exploratory and lacks a control group.' Intervention: 'The interventions include emesis in the spring and purgation in the autumn season.' Status and claim: 'Recruitment began in March 2025... Data analysis is pending' and 'The study will provide hypothesis-generating evidence, and the data will serve as a necessary precursor to adequately powered, confirmatory trials on the aging process.'
How much it shows. Added in the 2026-10-06 revision to answer the critic finding that the record cited no seasonal-Panchakarma intervention literature. It is the clearest located example of that literature and it is registered, which is what the finding asked for. It carries no result. It is a protocol: single-arm, no control group, 53 participants, surrogate endpoints only (serum malondialdehyde, total superoxide dismutase, telomerase activity) measured before and shortly after the procedure, and the authors themselves describe the output as hypothesis-generating and a precursor to adequately powered trials. Measuring an oxidative-stress marker before and after a purgative, with no control arm, cannot distinguish a rejuvenating effect from the acute physiological consequences of emesis, purgation, oleation, fomentation and a controlled post-procedure diet, nor from regression to the mean. It also does not test seasonality: the spring-emesis and autumn-purgation timing is fixed by the protocol, so there is no off-season comparison and the seasonal element of ritu shodhana is untested by construction. The CTRI number is quoted as the protocol paper prints it. It was not independently confirmed against the CTRI register; see notKnown on why CTRI itself was not searched.
A cross-sectional survey to evaluate the status of digestion in rotating- and fixed-shift workers. · Front Med (Lausanne) · 2026 · PMID 42519781
The nearest located empirical work on the daily-clock limb of kala-parinama, which the record previously left with no modern reference at all. From the abstract: 'The state of Jatharagni is influenced by several physiological factors, including season, time of day, age, constitution, dosha balance, and the quality and quantity of food consumed.' Method: 'A comparative, cross-sectional study was conducted among Information Technology (IT) employees... 350 employees were selected, comprising 175 fixed-shift workers and 175 rotating-shift workers (alternating between day and night shifts monthly) using a convenience sampling technique. Agnibala was assessed using a validated questionnaire.' Result: 'The study indicated that most fixed-shift workers had an Agnibala status consistent with their Prakriti. In contrast, 61.7% of rotating-shift workers reported a change in their Agni status due to their job nature, with many shifting to Vishamagni during their night shifts.' The authors' own closing caveat: 'These observations indicate a possible relationship between shift work, circadian rhythm disruption, and digestive health.'
How much it shows. Added in the 2026-10-06 revision. Cited for one thing: it is the closest located attempt to put an Ayurvedic time-governed function against a real disruption of the daily clock, and it is included because the record's dosha-kala component otherwise had no modern reference whatever. It is weak and it does not test what the record most needs tested. Cross-sectional, convenience sample from one technology park, and the outcome is a self-report questionnaire, so the headline 61.7% is workers reporting a change in their own digestion, not a measured change; the rotating-shift workers were assessed twice and the fixed-shift workers once, which is an asymmetry between the arms. No circadian marker was measured: no actigraphy, no cortisol, no core temperature, no melatonin. Crucially, it does not test the morning-kapha, noon-pitta, evening-vata assignment, and it does not test whether agni follows the classical daily sequence; it tests whether people whose schedule is inverted say their digestion has changed, which is compatible with the classical doctrine and with the ordinary chronobiology of shift work equally well. notKnown item 1 therefore stands unanswered and has been reworded rather than removed.
How to cite this entry
Age Ayurveda Nighantu, Kala-parinama (time, season and ripening as causes of disease)
, https://nighantu.ageayurveda.com/concept/kala-parinama/,
CC BY 4.0. The whole set is downloadable from the concept index.
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Data exported 2026-10-08.
Educational reference only. This page describes what a body of theory claims and how well it is evidenced. Nothing here is advice, and nothing here describes how any condition should be treated.