The 6 Ahara Parinamakara bhava as described in Charaka Samhita are the factors which are responsible for digestion. Each has specific role in the process of digestion. The word Lifestyle includes dietary habits, water drinking habits, conducts after meal etc which have been described in detail in Ayurveda. Improper Lifestyle leads to indigestion due to lack of Ahara Parinamakara bhava. 

In modern era of Lifestyle disorders like Diabetes mellitus, Obesity etc., occurrence of digestive system disorders is also very common. Behind them wrong dietary habits is the most important cause. As stated in texts of Ayurveda, disorders related to digestion are the root cause of all diseases (Brahmanand Tripathi, 2007). The main culprit of this chain is lack of Ahara Parinamakara bhava (factors responsible for digestion) which are essential for proper digestion.

Ahara Parinamakara bhava have been described by Acharya Charaka directly in Sharirasthana 6th adhyaya and indirectly in Grahanichikitsa adhyaya. They are six in number. (Brahmanand Tripathi, 2006) All of them have specific role in digestion. Lack of these leads to indigestion (Brahmanand Tripathi, 2006). In the present era of changing Lifestyle due to increased competition and stress, people are less conscious about their dietary habit which is a leading cause of digestive system disorders. The word Lifestyle includes Dietary habits, water drinking habits, conducts after meal etc. which have been described in detail in texts of Ayurveda (Saylee Deshmukh et al., 2015). 

Dietary habits include description of Ahara vidhi vidhana like Ushna (luke-warm), Snigdha (unctuous), Matravat (proper quantity) bhojana (meal) etc. described by Acharya Charaka (Brahmanand Tripathi, 2006). Water drinking habits include proper quantity and proper time of water intake, while conducts after meal have been described by Acharya Sushruta (Ananta Ram Sharma, 2008). Present study aims at elaboration of the concept of Ahara parinamakara bhava in correlation with Lifestyle. 

Aahara- Substances which are required to replenish or to maintain or for renewal of constantly deteriorating body is called Aahara.

Acharya Sushruta has explained that Panchabhautika substance consumed, which after Vipaka (digestion) nourishes respective Guna of Panchamahabhuta in body is called Aahara.

Parinama- Final stage or complete process of digestion (and metabolism) of ingested food is Parinama.

Bhava- Factors present in body are called as Bhava.

Thus, factors present in body which are responsible for complete digestion & metabolism (i.e. stage at which ingested food can replenish body) of food are called Aahara Parinamakara Bhava. As the digestion is mainly done by Agni, but some other factors also help in the digestion. They are six in number viz. Ushma, Vayu, Kleda, Sneha, Kala, Samyoga.

1) Ushma (Heat): Ushma is very important factor for digestion. For the digestive enzymes, Agni is the term given by Acharyas which itself shows the importance of heat in this process.

2) Vayu (Gas): According to Acharya Charaka, ‘Apakarshana’ is a function of Vayu (Brahmanand Tripathi, 2006). Its meaning has been given by commentator Chakrapani as to bring the distant situated food more in contact with Agni (Y.T. Acharya, 2008). 

3) Kleda (moisture): Kleda helps the food to get loosened which is essential for proper digestion (Brahmanand Tripathi, 2006). Loosened food gets more contac with digestive enzymes (William Beaumont, 1838). 

4) Sneha (unctuousness): It softens the food (Brahmanand Tripathi, 2006).

5) Kala (Time): It is normal time taken for digestion of food taken in normal quantity (Brahmanand Tripathi, 2006).

6) Samayoga (appropriate administration): Samayoga has been defined by commentator Chakrapani as administration of the proper food with consideration of Prakriti (constitution) etc. 

8 Ahara Vidhi visheshayatanani (factors determining the utility of food) (Brahmanand Tripathi, 2006). While commentator Yogindranath Sen defined it as proper combination of all above 5 Ahara Parinamakara bhavas (J.N.Sen, 1905). 

DISCUSSION:

The 6 Ahara Parinamakara Bhavas are the factors which are important for proper digestion. Among them first is Ushma which can be correlated with ‘Ushnam Ashniyat’

(intake of luke-warm food) which is one of the Ahara Vidhi Vidhana given by Acharya Charaka (Brahmanand Tripathi, 2006). In modern era, due to lack of time, mostly cold food is being eaten due to busy work schedules etc. According to modern researchers also, in stomach, the digestion goes on best at temperature of about 99F to 100F. When temperature lowers to that of atmosphere, the digestion process almost ceases. It renews after addition of calories In an experiment, ingestion of a single glass of water having temp of 50F, sufficed to depress heat of stomach upwards by 30F and normal temperature was regained after half an hour. So, intake of cold food,  ces in large quantity, drinking cold water after or during meal slow down the process of digestion (William Beaumont, 1838).

Description about Vayu given in texts gives clear idea about propelling movements of muscles of stomach which helps the food to be more in contact with gastric juice  William Beaumont, 1838). Cessation of gastric movements can occur in 2 ways either by internal pressure or external pressure. Internal pressure occurs by excessive  ntake of food and external pressure can occur due to tight clothes or wrong sitting or sleeping posture which is capable of increasing pressure on abdomen. 

Ahara Parinamakara Bhava Vayu can be correlated with Ahara Vidhi Vidhana- ‘Matravat bhojana’ and Bhojanottara Vidhi Vidhana- ‘Rajavat Asana.’ Matravat bhojana (intake of food in proper quantity) prevents the internal pressure due to excess food intake and Rajavat Asana (sitting in comfortable position) prevents the external  ressure.

Kleda can be correlated with water intake during meal. According to modern researchers, water intake during meal helps to loosen the food properly and also stimulates gastric secretions. (S Wyard, 1935). Sneha i.e. unctuousness is essential for proper digestion because according to modern researches, hard food can’t get digested properly (William Beaumont, 1838). Kala can be correlated with Jirne (intake of food after digestion of previous food), Nati-vilambita (not too slow) and Natidruta (not too fast) bhojana. Due to intake of food before digestion of previous food and slow intake of food, previous food gets mixed up with the product of food taken afterwards (Brahmanand Tripathi, 2006) and leads to indigestion (Hitesh A. Vyas, R. R. Dwivedi, 2011). About Nati-druta bhojana, proper chewing of food would ensure proper mixing and loosening of food in the buccal cavity. These days’ people eat very urgently where they do not allow the food to get chewed properly. Proper mixing of saliva is not ensured which may also lead to hard food entering the stomach which does not get easily digested. While slow intake of food results in mixing of digested and undigested food which leads to improper digestion (Brahmanand Tripathi,2006). So, Ati-druta (too slow) and Ativilambita (too fast) and frequent food intake are also harmful.

Samayoga i.e. combination of all Ahara Parinamakara Bhava or combination of all Ahara Vidhi Visheshayatanani can be correlated with Virya aviruddha (food items with inapposite potencies), Ajalpana, Ahasana, Tanmana bhojana (food intake without talking, laughing and with full concentration), Atmanamabhisamikshya (food suitable to person) (Avhad Anil et al., 2013). It leads to proper digestion of food and formation of proper Rasa, Rakta etc. Dhatu (Y.T.Acharya, 2008). But now a day people are busy in watching TV, Phone calls, Computer, Chatting, Talk and Laugh during meal. Due to this, they can’t decide the exact quantity of food needed which leads to indigestion (Brahmanand Tripathi, 2006). Food taken according to Prakriti of a person, leads to Dhatusamya and if it is being taken without consideration becomes Prakriti Viruddha and leads to Dhatuvaishamya (Brahmanand Tripathi, 2006). Wrong dietary habits like Adhyashana  intake of food before digestion of previous food), Vishamashana (intake of improper quantity of food at improper time) lead to disturbance in Ahara parinamakara bhava and ultimately vitiation of Agni (Sheela Kewat., 2015). In Ayurveda, it is stated t hat vitiated Agni is root cause for all diseases like Prameha, Sthaulya (Brahmanand Tripathi,2007). In modern sciences has accepted existence of Gut-Brain-Endocrine axis which involves Ghrelin-Leptin hormones, Insulin,  Orexins etc. Disturbance in this axis leads to diseases like Obesity, Diabetes mellitus which are among the top 10 Lifestyle disorders. The causes behind it are improper food habits (Annette L. Kirchgessner, 2002 & Y Wang, H Yang, 2004).

Ushma, Vayu, Kleda, Sneha, Kala and Samayoga are 6 Ahara Parinamakara Bhavas i.e. factors which are important for proper digestion. Each one has its own role in the process of digestion. Lifestyle includes Ahara Vidhi vidhana, Bhojanottara Vidhi vidhana, Ambupana Vidhi etc. Among them Ushma, Kleda, Sneha, Kala can be correlated successively with Ushna bhojana, Water intake during meal, Snigdha bhojana, Jirne bhojana and Atmanamabhisamikshya (food suitable to person). Vayu can be correlated with Matravat bhojana and Rajavat Asana. Samayoga can be correlated with Virya aviruddha, Ajalpana, Ahasana, Tanmana bhojana, Atmanamabhisamikshya (food suitable to person).