How to Understand the Digestion Process in Ayurveda?

Digestion is the breaking down of complex food particles into simpler ones through various enzymatic processes in the gastrointestinal tract. In Ayurveda, the heterogenous panchabhautika ahara (complex food) is converted into a homogeneous panchabhautika ahara (simpler or monomer form of the food). Digestion in Ayurveda is the action of Agni in three forms, Panchabhautikagni, Jatharagni, and Dhatwagni. The dosha also has a role in the process of digestion at different levels at different sites.

Digestion process in Ayurveda

The digestive system in Ayurveda can be included in both Annavaha srotas and Purishavaha srotas. The mouth and the upper gastrointestinal tract can be considered as Annavaha srotas and the large intestine and the rectum and anal canal can be called as Purishavaha srotas.

In the context of Ahara Paka in Ayurveda, the digestion that occurs from the mouth to the large intestine and then the forming of Ahara Rasa (absorption of the nutrients) and further its circulation to different organs forming the different tissues is explained. This whole process of Ahara Paka is known as Avastha Paka and Vipaka respectively.

Avastha Paka can be categorized into three stages in Ayurveda. Madhura Avastha Paka, Amla Avastha Paka, and Katu Avastha Paka. Vipaka is the stage where the seven dhatu are formed from the Ahara Rasa due to the action of the respective Dhatwagni.

In modern science, the digestion of carbohydrates, proteins, fats, and other nutrients occurs at different levels in the gastrointestinal tract.

The three Avastha Paka occur at three different levels in the gastrointestinal tract:

1. Madhura Avastha Paka – occurs in the mouth and Amashaya. Amashaya can be compared with the upper gastrointestinal tract in contemporary science.
2. Amla Avastha Paka – occurs in the Pachyamanashaya. This is the lower part of the stomach and the small intestine.
3. Katu Avastha Paka – occurs in the Pakwashaya which is the large intestine.

1. Madhura Avastha Paka: This is the first stage of digestion. It begins in the mouth. Prana Vayu and Bodhaka Kapha are present in the mouth. As soon as the food enters, with the help of Prana Vayu, the movement of food in the mouth occurs and then the Bodhaka kapha (salivary secretions or enzymes and the mucous) is mixed with the food and proper mastication takes place. The food then enters the esophagus and then with the help of Vyana Vata moves to the Amashaya (fundus part of the stomach). Kledaka kapha present in the upper gastrointestinal tract gets properly mixed with the food prepares the food for further digestion and propels towards the lower end of the stomach. Thus, phena Kapha dosha is released and the Madhura Bhava (sweet taste) of the food is produced in the Madhura Avastha Paka.
2. Amla Avastha Paka: This is the second stage of digestion occurring in the lower part of the stomach and the small intestines. This region in Ayurveda is known as Pachyamanashaya. The Pachyamanashaya is also called Grahani by some scholars of Ayurveda. The food here gets mixed up with the Pachaka Pitta and Samana Vayu. The action of these dosha breaks down the food particles in the stomach and propels them towards the small intestines. In the small intestines, the food gets mixed with the ‘Achcha Pitta’ secreted from the pittashaya (gall bladder). Pachaka Pitta can be correlated with digestive secretions like hydrochloric acid and others. The bile juice can be correlated with the Achcha Pitta. Due to the actions of these two forms of Pitta and Samana Vayu, the food is broken down into smaller particles and it attains the Amla bhava (sour taste) and the Pitta dosha is released. So, in the small intestines after the digestion, absorption takes place, and the undigested food moves into the large intestine with the help of Samana and Vyana Vata.
3. Katu Avastha Paka: The third stage of digestion in which the undigested food in Pakwashaya (which can be correlated with the large intestine) gets dried up by the action of Agni and the Apana Vata. Thus, gets converted into solidified waste and is excreted as Purisha (feces), and the fluid portion is absorbed and then excreted as Mutra (urine). During this stage, Katu bhava (bitter taste) of the food is attained and the Vata gets released in Pakwashaya. So, the excretion after this final stage of digestion happens and the waste is eliminated from the large intestines.

After the Avastha Paka from which the Ahara rasa is formed, it is now circulated to different organs to form the seven dhatus. During the formation of each dhatu, the digestion by the Dhatwagni at each dhatu occurs and the respective dhatu are formed. This process is known as Vipaka in Ayurveda. During this Vipaka phase, the individual dhatu is formed along with their byproducts and the waste metabolites.

So, in three Avastha Paka, the food gets digested and attains different tastes and the release of three doshas. In Vipaka, the individual dhatwagni acts on the Ahara Rasa to form the dhatu, their byproducts, and waste products. The mouth and upper gastrointestinal tract are the sites where the Madhura Avastha Paka takes place, Amla Avastha Paka occurs in the lower part of the stomach and the small intestine. The large intestine is the seat of Katu Avastha Paka.

Conclusion

Ahara Paka explained in Ayurveda is a systematized process of digestion. It is a well-defined procedure of breaking down complex food particles into simpler particles The Ahara paka is the digestion occurring from the mouth to the large intestine and then at the various levels of dhatu.  The three Avastha Paka give rise to Madhura, Amla, and Katu tastes, and the Kapha, Pitta, and Vata are formed respectively. Amashaya, Pachyamanashaya, and Pakwashaya are the places where these Avastha Paka take place. Vipaka is the process of dhatu formation by the action of Dhatwagni present in each dhatu. Prana Vata, Samana Vata, Vyana Vata, Pachaka Pitta, Bodhaka Kapha, and Kledaka Kapha are the dosha involved in the process of Ahara Paka. 

References

1. https://ijcrt.org/download.php?file=IJCRT2307258.pdf
2. https://www.researchgate.net/publication/343537124_A_Critical_Appraisal_on_Digestive_System_Avastha_Paka_of_Ayurveda_in_the_Modern_Physiological_Perspective
3. http://www.iamj.in/images/upload/3407_3413.pdf