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<div style='text-align:justify;'>The term ‘ritucharya’ is derived from two different words ‘ritu’ meaning season and ‘charya’ means ‘regimen’. Seasonal regimen prescribed for preservation of health and prevention of [[Vyadhi|diseases]] is termed as ‘ritucharya’.     

<div style='text-align:justify;'>The term ‘ritucharya’ is derived from two different words: ‘ritu’ meaning season and ‘charya’ meaning ‘regimen’. Seasonal regimen prescribed for preservation of health and prevention of [[Vyadhi|diseases]] is termed as ‘ritucharya’.     

[[Ayurveda|Ayurveda]], the science of [[Ayu|life]] defined the human [[Sharira|body (''sharira'')]] is always in a state of change towards degeneration called as [[Sharira|''sharira'' (human body)]] [Vaidyaka shabdasindhu]. Ancient scriptures were aware of astronomy; they keenly observed the change in seasons with respect to the sun, moon, stars, wind, and rainfall. The concept of ''“yat pinde tat brahmande‘''- whatever there is in the environment is also there is the human [[Sharira|body]] is applied in understanding health. This leads to appreciating changes in the human [[Sharira|body]] according to seasons and regimens are made accordingly. The seasonal regimen's main aim is to prevent [[Vyadhi|diseases]] due to the derangement of [[Dosha|dosha]]. Hence ritucharya is one of the ways to be in synchronize with ever-changing nature and being healthy all at the same time. </div>

[[Ayurveda|Ayurveda]], the science of [[Ayu|life]] defined the human [[Sharira|body (''sharira'')]] is always in a state of change towards degeneration called as [[Sharira|''sharira'' (human body)]] [Vaidyaka shabdasindhu]. Ancient scriptures were aware of astronomy; they keenly observed the change in seasons with respect to the sun, moon, stars, wind, and rainfall. The concept of ''“yat pinde tat brahmande‘''- whatever there is in the environment is also there is the human [[Sharira|body]] is applied in understanding health. This leads to appreciating changes in the human [[Sharira|body]] according to seasons and regimens are made accordingly. The seasonal regimen's main aim is to prevent [[Vyadhi|diseases]] due to the derangement of [[Dosha|dosha]]. Hence ritucharya is one of the ways to be in synchronize with ever-changing nature and being healthy all at the same time. </div>

== Nirukti (etymology) ==

== Nirukti (etymology) ==

<div style='text-align:justify;'>In [[Ayurveda|Ayurveda]], the season is represented by the term ''[[Kala|kala]]''. [[Kala|Kala]] is a broad term. In one context it is mentioned as seasons, while in some other context, it merely represents time. The term ritu is the most suitable term to explain seasons. The term ''ritu'' refers to a specific period having a cyclic rotation. In the context of ritucharya, ritu is mentioned as the term in which nature expresses itself in sequence, in specific forms of a two-month duration (dvau masau). [A.Hr. Sutra Sthana 3/1 Hemadri]. Charya means regimen or action. Dalhana defines ritucharya as the regimen that should be followed concerning seasons.[Su.Sa. Sutra Sthana 6/1 Dalhana] Vagbhata defines it as the changes in [[Ahara vidhi|diet]] and practices with respect to changes in climate conditions like heat, cold, rain etc. [A.Sa.Sutra Sthana 3/1 Hemadri] </div>

<div style='text-align:justify;'>In [[Ayurveda|Ayurveda]], the season is represented by the term ''[[Kala|kala]]''. [[Kala|Kala]] is a broad term. In one context it is mentioned as seasons, while in some other context, it merely represents time. The term ritu is the most suitable term to explain seasons. The term ''ritu'' refers to a specific period having a cyclic rotation. In the context of ritucharya, ritu is mentioned as the term in which nature expresses itself in sequence, in specific forms of a two-month duration (dvau masau). [A.Hr. Sutra Sthana 3/1 Hemadri]. Charya means regimen or action. Dalhana defines ritucharya as the regimen that should be followed concerning seasons. [Su.Sa. Sutra Sthana 6/1 Dalhana] Vagbhata defines it as the changes in [[Ahara vidhi|diet]] and practices with respect to changes in climate conditions like heat, cold, rain etc. [A.Sa. Sutra Sthana 3/1 Hemadri] </div>

== Concept of ritucharya (seasonal regimen) ==

== Concept of ritucharya (seasonal regimen) ==

=== Seasonal regimen: ===

=== Seasonal regimen: ===

<div style='text-align:justify;'>The strength and lusture is enhanced by following suitable [[Ahara vidhi|diet]] and regimen for every season. [Cha. Sa. Sutra Sthana 6/3] The year is divided into six parts according to seasons. The northward movement of the sun and its act of dehydration brings about three seasons beginning from late winter to summer. The southward movement of sun and its act of hydration gives rise to the rainy season to early winter. [Cha. Sa. Sutra Sthana 6/4]  Qualitative dietetics includes the wholesome and unwholesome [[Ahara vidhi|diet]] and lifestyle regimen as per seasons. [Cha. Sa. Sutra Sthana 6/51] </div>

<div style='text-align:justify;'>The strength and lusture is enhanced by following suitable [[Ahara vidhi|diet]] and regimen for every season. [Cha. Sa. [[Sutra Sthana]] 6/3] The year is divided into six parts according to seasons. The northward movement of the sun and its act of dehydration brings about three seasons beginning from late winter to summer. The southward movement of sun and its act of hydration gives rise to the rainy season to early winter. [Cha. Sa. [[Sutra Sthana]] 6/4]  Qualitative dietetics includes the wholesome and unwholesome [[Ahara vidhi|diet]] and lifestyle regimen as per seasons. [Cha. Sa. [[Sutra Sthana]] 6/51] </div>

=== Seasonal purification: ===

=== Seasonal purification: ===

<div style='text-align:justify;'>Purpose of seasonal purification procedures is to maintain normalcy of dohsa, [[Dhatu|dhatus]] in different seasons. One should eliminate the accumulated [[Dosha|dosha]] in the first month of spring, rainy and winter. [Cha. Sa. Sutra Sthan 7/46]. To prevent seasonal [[Vyadhi|diseases]], [[Dosha|doshas]] accumulated during [[Hemanta|hemanta]] (December – February) be eliminated in the month of [[Chaitra|Chaitra]] (March-April). Those accumulated during summer(April-June) in the month of [[Shravana|Shravana]] (July-August). The [[Dosha|dosha]] accumulated during railny season (August- October) should  be eliminated in the month of Margasheersha (November-Octomber)[Cha.Sa. Sutra Sthana 7/45]. The elimination therapies should be administered only in seasons with moderate heat and cold nature. In other seasons having extreme cold, heat or rain, such therapies should not be administered. Moderate seasons are enjoyable and they do not adversely affect the conditions of the [[Sharira|body]] and drugs. [Cha. Sa.Vimana Sthana 8/126]  However, in emergency situations, when the therapy is utmost needed,  one should administer the therapy with great care after modifying the seasonal effects sufficiently by artificial means, producing qualities contrary to the seasons and by making the measure appropriate in standard potency with variation in combination, processing and quantity. [Cha. Sa.Vimana Sthana 8/126] </div>

<div style='text-align:justify;'>Purpose of seasonal purification procedures is to maintain normalcy of [[dosha]], [[Dhatu|dhatus]] in different seasons. One should eliminate the accumulated [[Dosha|dosha]] in the first month of spring, rainy and winter. [Cha. Sa. [[Sutra Sthana]] 7/46] To prevent seasonal [[Vyadhi|diseases]], [[Dosha|doshas]] accumulated during [[Hemanta|hemanta]] (December – February) be eliminated in the month of [[Chaitra|Chaitra]] (March-April). Those accumulated during summer(April-June) in the month of [[Shravana|Shravana]] (July-August). The [[Dosha|dosha]] accumulated during railny season (August- October) should  be eliminated in the month of Margasheersha (November-Octomber)[Cha.Sa. [[Sutra Sthana]] 7/45]. The elimination therapies should be administered only in seasons with moderate heat and cold nature. In other seasons having extreme cold, heat or rain, such therapies should not be administered. Moderate seasons are enjoyable and they do not adversely affect the conditions of the [[Sharira|body]] and drugs. [Cha. Sa. [[Vimana Sthana]] 8/126]  However, in emergency situations, when the therapy is utmost needed,  one should administer the therapy with great care after modifying the seasonal effects sufficiently by artificial means, producing qualities contrary to the seasons and by making the measure appropriate in standard potency with variation in combination, processing and quantity. [Cha. Sa.[[Vimana Sthana]] 8/126] </div>

=== Seasonal conditions in nasal administration therapy: ===

=== Seasonal conditions in nasal administration therapy: ===

<div style='text-align:justify;'>In summer, the nasal administration therapy should be given in the morning. In winter, it should be given during mid-day. In rainy season, it should be given when the sky is clear and not cloudy. In the case of an emergency, it can be given in the seasons other than early rains, autumn and spring by artificially creating the congenial environment [Cha. Sa. Siddhi Sthana 2/23] </div>

<div style='text-align:justify;'>In summer, the nasal administration therapy should be given in the morning. In winter, it should be given during mid-day. In rainy season, it should be given when the sky is clear and not cloudy. In the case of an emergency, it can be given in the seasons other than early rains, autumn and spring by artificially creating the congenial environment. [Cha. Sa. [[Siddhi Sthana]] 2/23] </div>

=== Ritusandhi (period of climatic transition): ===

=== Ritusandhi (period of climatic transition): ===

<div style='text-align:justify;'>The last seven days of a season and the first seven days of the next season is considered as period of transition of climate ([[Ritusandhi|ritusandhi]]). In this period, one should taper the regimens of the previous season and practice those of the next season in a gradual, phased manner. Immediate abandoning and adoption of regimens causes various [[Vyadhi|diseases]] due to improper adoption. [A.Hr. Sutra Sthan3/58] </div>

<div style='text-align:justify;'>The last seven days of a season and the first seven days of the next season is considered as period of transition of climate ([[Ritusandhi|ritusandhi]]). In this period, one should taper the regimens of the previous season and practice those of the next season in a gradual, phased manner. Immediate abandoning and adoption of regimens causes various [[Vyadhi|diseases]] due to improper adoption. [A. Hr. Sutra Sthana 3/58] </div>

=== Seasons, constellations and Sun signs: ===

=== Seasons, constellations and Sun signs: ===

<div style='text-align:justify;'>When the sun is in aries and taurus constellations, it is greeshma ritu (summer April-May). When in Gemini and cancer, it is pravrit (early rains, June-July). When in leo and virgo, it is rainy season, (August-September). When it is in libra and scorpio, it is sharada (Autumn, October-November). When it is in sagitarrus and capricorn, it is Hemanta (winter, December-January). When the sun is in aquarius and piscus, it is vasanta (Spring, February-March). [Sha.Sa.2/25-26]  This also identifies sunsigns according to the birth.  </div>

<div style='text-align:justify;'>When the sun is in aries and taurus constellations, it is grishma ritu (summer April-May). When in Gemini and cancer, it is pravrit (early rains, June-July). When in leo and virgo, it is rainy season, (August-September). When it is in libra and scorpio, it is sharada (Autumn, October-November). When it is in sagitarrus and capricorn, it is hemanta (winter, December-January). When the sun is in aquarius and piscus, it is vasanta (Spring, February-March). [Sha.Sa. 2/25-26]  This also identifies sun signs according to the birth.  </div>

=== Concept of Yamadamshtra: ===

=== Concept of Yamadamshtra: ===

<div style='text-align:justify;'>The last eight days of kartika masa (third week of November) and  the first eight days of avagrahayana (fourth week of November) are known as [[Yamadamshtra|yamadamshtra]] kaala. During this period, one can be healthy if he takes only small quantity of food. [Sha.Sa. 2/30] </div>

<div style='text-align:justify;'>The last eight days of kartika masa (third week of November) and  the first eight days of avagrahayana (fourth week of November) are known as [[Yamadamshtra|yamadamshtra]] [[kala]]. During this period, one can be healthy if he takes only small quantity of food. [Sha.Sa. 2/30] </div>

=== Concept of ritu haritaki: ===

=== Concept of ritu haritaki: ===

<div style='text-align:justify;'>Seasonal changes shall be considered while taking some medicines for specific actions. A person, who wishes to attain the vitalizing actions of haritaki shall consume it with specific substances as per seasons. Haritaki shall be taken with salt during rainy season, with sugar during post monsoon period, with dry ginger during winter, with pepper during autumn with honey during spring and with jaggery during summer [Bha.Pra.Purva khanda 6/34]  </div>

<div style='text-align:justify;'>Seasonal changes shall be considered while taking some medicines for specific actions. A person, who wishes to attain the vitalizing actions of haritaki shall consume it with specific substances as per seasons. Haritaki shall be taken with salt during rainy season, with sugar during post monsoon period, with dry ginger during winter, with pepper during autumn with honey during spring and with jaggery during summer. [Bha.Pra.Purva khanda 6/34]  </div>

{| class="wikitable"

{| class="wikitable"

|+ Table: Anupana according to seasons for consuming haritaki

|+ Table: Anupana according to seasons for consuming haritaki

=== Autumnal fever: ===

=== Autumnal fever: ===

<div style='text-align:justify;'>[[Sharira|Body]] is unable to cope up with suddent climatic changes. By sudden increase in heat at the end of the rainy season, [[Pitta|pitta]] gets mobilized and aggravated. This leads to fever that occurs mostly in the early winter. This is called sharada jvara or autumnal fever. [Bhe. Sa. Sutra Sthana 13/10]  </div>

<div style='text-align:justify;'>[[Sharira|Body]] is unable to cope up with suddent climatic changes. By sudden increase in heat at the end of the rainy season, [[Pitta|pitta]] gets mobilized and aggravated. This leads to fever that occurs mostly in the early winter. This is called sharada [[jwara]] or autumnal fever. [Bhe. Sa. Sutra Sthana 13/10]  </div>

=== Prevention of occurrences of diseases : ===

=== Prevention of occurrences of diseases : ===

== Contemporary approach and researches ==

== Contemporary approach and researches ==

=== Impact of seasonal variation on health: ===

=== Impact of seasonal variation on health: ===

<div style='text-align:justify;'>Three causes viz. improper union of senses with objects ([[Asatmendriyarthasamyoga|asatmendriyartha samyoga]]), intellectual defect ([[Prajnaparadha|prajnaparadha]]) and time ([[Parinama|parinama]]) are responsible for manifestation of [[Vyadhi|diseases]]. Among these, [[Parinama|parinama]] or [[Kala|kala]] plays an important role in the health of the individuals. The excess (atiyoga), deficient (ayoga) and improper (mithya yoga) of [[Kala|kala]] results in [[Dosha|dosha]] vitiation.  As a part of normal seasonal variation also, [[Dosha|doshas]] get vitiated in the individuals. A proper management of the environmental determinants of health is essential for the promotion of positive health and thereby preventing [[Vyadhi|diseases]]. Recognition that human health can be affected by a wide range of ecological disruptions, consequent upon climate change, is a recent development in modern scientific world. But the idea that human health and [[Vyadhi|disease]] are linked to climate probably predates written history. The Greek physician Hippocrates (about 400 BC) related epidemics to seasonal weather changes, stating that physicians should have “due regard to the seasons of the year, and the [[Vyadhi|diseases]] which they produce, and to the states of the wind peculiar to each country and the qualities of its water”. He exhorts them to take note of “the water which people use, whether they be marshy and soft, or hard and running from elevated and rocky situations, and unfit for cooking,” and to observe “the localities of towns, and of the surrounding country, whether they are low or high, hot or cold, wet or dry and of the diet and regimen of the inhabitants”<ref>Hippocrates. Airs, waters and places. An essay on the influence of climate, water supply and situation on health. In: Hippocratic Writings. Lloyd G.E.R. ed. London, UK, Penguin, 1978.</ref> <br/>All these facts are well studied and presented by Ayurveda scientists along with the management protocol. More over recent studies have shown changes in the biochemical parameters along with seasonal variations. The physical health impacts of climate change, especially infections, allergies, respiratory and cardiovascular [[Vyadhi|diseases]] are now well recognized. These objective evidences can be considered as a reflection of the physiological imbalance occurring in the equilibrium of [[Tridosha|tridoşha]] due to seasonal variations, progressing to a pathological state as a result of unhealthy diet and regimen. So, in order to prevent seasonal outbreak of [[Vyadhi|diseases]], a regimen should be designed, including currently available facilities. For that a thorough knowledge of the physiological imbalances occurring in various seasons in terms of [[Dosha|dosha]] vitiation, status of [[Agni|agni]] and [[Bala|bala]] are very essential.<br/>The season is a variation for a particular time which includes environmental factors which consist of nature of land, water, atmospheric temperature, humidity, wind, rain, clouds and atmospheric pressure. All these factors undergo a continous change and at a time, when no two movements are exactly alike in a given place.<ref>Jangid C, Vyas HA, Dwivedi RR. Concept of Ritus and their effect on Bala. AYU Int Res J Ayurveda. 2009; 30:11–5).</ref> <br/>Some studies are carried out to eshtablish the influence of seasonal changes on the  development of opportunistic [[Vyadhi|diseases]]. These show the effect of photo period on immune function and hormone synthesis has a positive result. It also showed that time of the year is important in changing the glucocortcoid concentrations in unstressed and stressed animals.<ref>Nelson RJ, Demas GE. Seasonal changes in immune function3. Q Rev Biol. 1996; 71:511–48.</ref><ref name="ref6">Romero LM. Seasonal changes in plasma gluco-corticoid concentrations in free-living vertebrates. Sci Direct. 2002;9:1147–51</ref><br/>A study was conducted to assess the biophysical, and biochemical changes and provocation of [[Tridosha|tridosha]] in [[Ritusandhi|ritusandhi]]. It shows that there was a increasing and decreasing pattern in biochemical changes within normal variations, but the changes were not remarkable. The study is also evident of occuring [[Jwara|jwara (fever)]], pratishyaya (rhinitis), alasya (tiredness) frequently with dominance of [[Vata dosha|vata]] and [[Kapha dosha|kapha]] provocation.<ref name="ref7">Mallika KJ. Critical study of Swastha-Catuska w.s.r. to Biophysical and Biochemical changes in Rtusandhi. MD (Ayu) Thesis. Jamnagar: Gujarat Ayurved University; 2002.</ref></br>Based on the principles of ritucharya, a study has been conducted on healthy volunteers to assess the [[Bala|bala]] (physical strength) in different ritus (seasons). The study showed that maximum [[Bala|bala]] was seen during winter ([[Hemanta|hemanta]] ritu), moderate [[Bala|bala]] during spring ([[Vasanta|vasanta]] ritu) and minimum [[Bala|bala]] during rainy season ([[Varsha|vaasha]] ritu).<ref name="ref6"/> Other systems of medicine also considered the effect of seasons on health. For instance, father of modern medicine, Hippocrates says that whoever wishes to investigate medicine properly should proceed thus in the first place to consider the seasons of the year and what affects of each of them produces. Tibetian system also believes that seasonal regimens are powerful instruments in prevention of [[Vyadhi|diseases]].<ref name="ref7"/> </br>Variation in state of [[Dosha|dosha]] in different ritu results in [[Vyadhi|diseases]] if the prescribed regiment is not followed. For example, increased occurrence of flu, dry skin in winter, heat stroke in summer, pollen allergy in spring, high incidence of air and water borne [[Vyadhi|diseases]] in rainy season and skin [[Vyadhi|diseases]] in autumn are observed.<ref>Valiathan MS. Towards Ayurvedic Biology ,Bangalore: Indian Academy of Sciences; 2006.</ref> Few studies show positive correlation between attack of asthma in winter season. Contemporary science also have evidences regarding seasonal affectective disorders (SADs).<ref>Tabers Cyclopedic Medical Dictionary. 18th ed. New Delhi: Jaypee Brothers Medical Publisher (P) Ltd; 2000</ref>  <br/>Understainding of Ayurvedic concept of seasonal divisions (ritu vibhaga) is mainly based on specific characteristic features of seasons (lakshanas), based on the hindu calendar months ([[Masa|masa]]) and stars ([[Rashi|rashi]]). In present scenario, the characteristic features of classically mentioned characteristic features are not uniform all over the geaographical areas. But still specific features during seasons based on biological and external environmental changes during the each seasons are observed. In this connection, a few reviews  eshtablish the relation between ritus and gut microbial changes and their effect on health. The food habits and lifestyle changes during each season (ritu) changes the free living microorganism in gut. This increases individual susceptibility to inflammatory as well as metabolic [[Vyadhi|diseases]] such as  non- communicable diseases. Adopting a proper seasonal regimen including seasonal purification enhances the gut acclimatization, thus prevent the  pathological manifestation of seasonal [[Vyadhi|diseases]] and maintain health.<ref>Deppti R, Vandana Rani .M, Delvin T Robin, Anushree Dilip. Adopting seasonal regimen (Ritucharya) to modulate the seasonal variation in gut microbiome. Journal of ethics food : 2-2021</ref> <br/>A seasonal change in immune function has also been observed by researchers during animal studies. Immunological parameters like spleen mass, white blood cells, cellular immunity, IgG and IgM levels showed seasonal changes. Cellular immunity was found to be high in winter than in summer.<ref>De Li Xu,Xiao Kai Hu, Yufen Tian. Seasonal variation in cellular and humaoral immunity in male striped hamsters, Biology, open 2018,7 bio038489,doi- 10.1242/bio 03848</ref> </div>

<div style='text-align:justify;'>Three causes viz. improper union of senses with objects ([[Asatmendriyarthasamyoga|asatmendriyartha samyoga]]), intellectual defect ([[Prajnaparadha|prajnaparadha]]) and time ([[Parinama|parinama]]) are responsible for manifestation of [[Vyadhi|diseases]]. Among these, [[Parinama|parinama]] or [[Kala|kala]] plays an important role in the health of the individuals. The excess (atiyoga), deficient (ayoga) and improper (mithya yoga) of [[Kala|kala]] results in [[Dosha|dosha]] vitiation.  As a part of normal seasonal variation also, [[Dosha|doshas]] get vitiated in the individuals. A proper management of the environmental determinants of health is essential for the promotion of positive health and thereby preventing [[Vyadhi|diseases]]. Recognition that human health can be affected by a wide range of ecological disruptions, consequent upon climate change, is a recent development in modern scientific world. But the idea that human health and [[Vyadhi|disease]] are linked to climate probably predates written history. The Greek physician Hippocrates (about 400 BC) related epidemics to seasonal weather changes, stating that physicians should have “''due regard to the seasons of the year, and the [[Vyadhi|diseases]] which they produce, and to the states of the wind peculiar to each country and the qualities of its water''”. He exhorts them to take note of “''the water which people use, whether they be marshy and soft, or hard and running from elevated and rocky situations, and unfit for cooking,''” and to observe “the localities of towns, and of the surrounding country, whether they are low or high, hot or cold, wet or dry and of the diet and regimen of the inhabitants”<ref>Hippocrates. Airs, waters and places. An essay on the influence of climate, water supply and situation on health. In: Hippocratic Writings. Lloyd G.E.R. ed. London, UK, Penguin, 1978.</ref> <br/>All these facts are well studied and presented by Ayurveda scientists along with the management protocol. More over recent studies have shown changes in the biochemical parameters along with seasonal variations. The physical health impacts of climate change, especially infections, allergies, respiratory and cardiovascular [[Vyadhi|diseases]] are now well recognized. These objective evidences can be considered as a reflection of the physiological imbalance occurring in the equilibrium of [[tridosha]] due to seasonal variations, progressing to a pathological state as a result of unhealthy diet and regimen. So, in order to prevent seasonal outbreak of [[Vyadhi|diseases]], a regimen should be designed, including currently available facilities. For that a thorough knowledge of the physiological imbalances occurring in various seasons in terms of [[Dosha|dosha]] vitiation, status of [[Agni|agni]] and [[Bala|bala]] are very essential.<br/>The season is a variation for a particular time which includes environmental factors which consist of nature of land, water, atmospheric temperature, humidity, wind, rain, clouds and atmospheric pressure. All these factors undergo a continuous change and at a time, when no two movements are exactly alike in a given place.<ref>Jangid C, Vyas HA, Dwivedi RR. Concept of Ritus and their effect on Bala. AYU Int Res J Ayurveda. 2009; 30:11–5).</ref> <br/>Some studies are carried out to establish the influence of seasonal changes on the  development of opportunistic [[Vyadhi|diseases]]. These show the effect of photo period on immune function and hormone synthesis has a positive result. It also showed that time of the year is important in changing the glucocortcoid concentrations in unstressed and stressed animals.<ref>Nelson RJ, Demas GE. Seasonal changes in immune function3. Q Rev Biol. 1996; 71:511–48.</ref><ref name="ref6">Romero LM. Seasonal changes in plasma gluco-corticoid concentrations in free-living vertebrates. Sci Direct. 2002;9:1147–51</ref><br/>A study was conducted to assess the biophysical, and biochemical changes and provocation of [[Tridosha|tridosha]] in [[Ritusandhi|ritusandhi]]. It shows that there was a increasing and decreasing pattern in biochemical changes within normal variations, but the changes were not remarkable. The study is also evident of occuring [[Jwara|jwara (fever)]], pratishyaya (rhinitis), alasya (tiredness) frequently with dominance of [[Vata dosha|vata]] and [[Kapha dosha|kapha]] provocation.<ref name="ref7">Mallika KJ. Critical study of Swastha-Catuska w.s.r. to Biophysical and Biochemical changes in Rtusandhi. MD (Ayu) Thesis. Jamnagar: Gujarat Ayurved University; 2002.</ref></br>Based on the principles of ritucharya, a study has been conducted on healthy volunteers to assess the [[Bala|bala]] (physical strength) in different ritus (seasons). The study showed that maximum [[Bala|bala]] was seen during winter ([[Hemanta|hemanta]] ritu), moderate [[Bala|bala]] during spring ([[Vasanta|vasanta]] ritu) and minimum [[Bala|bala]] during rainy season ([[varsha]] ritu).<ref name="ref6"/> Other systems of medicine also considered the effect of seasons on health. For instance, father of modern medicine, Hippocrates says that whoever wishes to investigate medicine properly should proceed thus in the first place to consider the seasons of the year and what affects of each of them produces. Tibetian system also believes that seasonal regimens are powerful instruments in prevention of [[Vyadhi|diseases]].<ref name="ref7"/> </br>Variation in state of [[Dosha|dosha]] in different ritu results in [[Vyadhi|diseases]] if the prescribed regiment is not followed. For example, increased occurrence of flu, dry skin in winter, heat stroke in summer, pollen allergy in spring, high incidence of air and water borne [[Vyadhi|diseases]] in rainy season and skin [[Vyadhi|diseases]] in autumn are observed.<ref>Valiathan MS. Towards Ayurvedic Biology ,Bangalore: Indian Academy of Sciences; 2006.</ref> Few studies show positive correlation between attack of asthma in winter season. Contemporary science also have evidences regarding seasonal affectective disorders (SADs).<ref>Tabers Cyclopedic Medical Dictionary. 18th ed. New Delhi: Jaypee Brothers Medical Publisher (P) Ltd; 2000</ref>  <br/>Understainding of Ayurvedic concept of seasonal divisions (ritu vibhaga) is mainly based on specific characteristic features of seasons (lakshanas), based on the hindu calendar months ([[Masa|masa]]) and stars ([[Rashi|rashi]]). In present scenario, the characteristic features of classically mentioned characteristic features are not uniform all over the geaographical areas. But still specific features during seasons based on biological and external environmental changes during the each seasons are observed. In this connection, a few reviews  eshtablish the relation between ritus and gut microbial changes and their effect on health. The food habits and lifestyle changes during each season (ritu) changes the free living microorganism in gut. This increases individual susceptibility to inflammatory as well as metabolic [[Vyadhi|diseases]] such as  non- communicable diseases. Adopting a proper seasonal regimen including seasonal purification enhances the gut acclimatization, thus prevent the  pathological manifestation of seasonal [[Vyadhi|diseases]] and maintain health.<ref>Deppti R, Vandana Rani .M, Delvin T Robin, Anushree Dilip. Adopting seasonal regimen (Ritucharya) to modulate the seasonal variation in gut microbiome. Journal of ethics food : 2-2021</ref> <br/>A seasonal change in immune function has also been observed by researchers during animal studies. Immunological parameters like spleen mass, white blood cells, cellular immunity, IgG and IgM levels showed seasonal changes. Cellular immunity was found to be high in winter than in summer.<ref>De Li Xu,Xiao Kai Hu, Yufen Tian. Seasonal variation in cellular and humaoral immunity in male striped hamsters, Biology, open 2018,7 bio038489,doi- 10.1242/bio 03848</ref> </div>

===Clinical researches on ritucharya ===

===Clinical researches on ritucharya ===

<ol style='text-align:justify;'><li>Abhashankar (2021). A preventive trial on ritucharya in seasonal disease of Greeshma ritu- A non-randomized controlled trial . PG Dissertation, KUHS, Kerala.</li>

<ol style='text-align:justify;'><li>Abha shankar (2021). A preventive trial on ritucharya in seasonal disease of Greeshma ritu- A non-randomized controlled trial . PG Dissertation, KUHS, Kerala.</li>

<li>Ramesh Kumar L (2016). Concept of Kaala in relation to ecological, physiological and biochemical changes in Greeshma ritu. PhD Thesis, GAU, Jamnagar, Gujarat.</li>

<li>Ramesh Kumar L (2016). Concept of Kaala in relation to ecological, physiological and biochemical changes in Greeshma ritu. PhD Thesis, GAU, Jamnagar, Gujarat.</li>

<li>Lakshmi V. (2012). An interventional trial on preomotion of positive health through seasonal purification w.s.r toSarat Ritu. PG Dissertation, KUHS, Kerala</li>

<li>Lakshmi V. (2012). An interventional trial on preomotion of positive health through seasonal purification w.s.r toSarat Ritu. PG Dissertation, KUHS, Kerala</li>

<li>Seasonal regimen in Autumn incuding Hamsodaka [A.Hr.Sutra Sthana 3/49-54]</li>

<li>Seasonal regimen in Autumn incuding Hamsodaka [A.Hr.Sutra Sthana 3/49-54]</li>

<li>The rasa and properties of food items recommended for use in each ritu [A.Hr.Sutra Sthana 3/54-55].</li></ul>

<li>The rasa and properties of food items recommended for use in each ritu [A.Hr.Sutra Sthana 3/54-55].</li></ul>

<li style="font-weight: bold;">Sarangadhara Samhita (14 AD):</li>

<li style="font-weight: bold;">Sharangadhara Samhita (14 AD):</li>

<ul><li>Dosha accumulation, increase and decrease as per seasons [Sha.Sa. 2/27-28]</li>

<ul><li>Dosha accumulation, increase and decrease as per seasons [Sha.Sa. 2/27-28]</li>

<li>Seasons and status of tridoshas : Movement of the sun from one stellar constellation to the other makes for the six seasons during which the trodosas undergo mild increase, profound increase and derease to normal [Sha.Sa. 2/25]</li>

<li>Seasons and status of tridoshas : Movement of the sun from one stellar constellation to the other makes for the six seasons during which the trodosas undergo mild increase, profound increase and derease to normal [Sha.Sa. 2/25]</li>