There are two phases of digestion explained elaborately in Ayurveda. One of them is known as Prakapa metabolism in digestion. This phase involves the conversion that takes place within the gastrointestinal tract, up to and including the absorption through the intestinal walls. The gastrointestinal tract and its surrounding area are mainly divided into three sections as per the specific dosha functions governing the concerned area. The upper portion of the gastrointestinal tract is dominated by the cohesive, lubricating and liquefying functions of Kapha dosha. The middle part is subjugated by the transformative actions of Pitta dosha and the lower zone is dominated by the separating, absorptive and drying processes of Vata dosha.
Prakapa digestion starts with eating and swallowing. Ayurveda defines that the three stages of the Prakapa metabolism in digestion are referred to as the three transient phases of metabolism. Each dosha has associated with a prominent taste or rasa. The basic natures of the five elements and their combinations produce six different tastes and these are sweet, salty, sour, pungent, astringent and bitter. The tastes hold special significance in Prakapa digestion. As the food particles moves through the three particular dosha stages, it takes on the taste associated with the dosha particularly governing the concerned zone. The basic tastes will predominate regardless of the taste the food has at the time it was eaten. The food just after consuming enters the kapha zone, which is the first stage of transient metabolism. At this stage it gets moistened and liquefied. As because of the watery secretions is in abundance at this particular zone, the food increases in volume. It acquires a principally the sweet taste and at this initial stage of Prakapa digestion, the food becomes even sweeter.
In the second phase of Prakapa metabolism, the qualities of Agni begin to take over. In this mid-zone temperature level rises because of the conversion process that takes place here. The food particles which are bound together and liquefied by kapha`s action combine with the acid secretions from the glands present in the pitta zone. They are now broken down and homogenized and they can not be recognized s distinct food particles any longer. Moreover, the food mass takes on the sour taste that is associated with the pitta dosha. At the final stage of Prakapa or transient metabolism, the changed food mass takes entry into the vata zone. Here the process of absorption starts. Under the influence of the vata dosha, the nutrient portions of the food substance are separated from the parts which are not used. In the entire process, water gets separated from earth and the food volume decreases. Influence of Agni is still active at the last stage. The food mass becomes pungent in taste.
Nature of Prakapa Metabolism in Digestion
In Ayurveda, it is defined that the entire metabolic sequence of the human body is a universal phenomenon. As the food substance moves through the three different phases of Prakapa digestion the body actually feels the influence of every single as it consecutively dominates the process of digestion. For instance, in the very first phase of Prakapa digestion, the pressure of kapha forms a sleepy and heavy feeling. When the food leaves the stomach and reaches the zone of the pitta, the transformation processes raise the body temperature giving a warm and thirsty feeling. When the food mass enters the final and the last stage, the influence of vata stimulates the body for some activities.
The length of time taken for food to pass through each of the single phase of Prakapa metabolism is considered as significant as it is a clue to the source of the digestive problem. Moreover, foods which are too sweet, oily, cold or heavy take longer time to digest as they demand stronger digestive fire. In the same manner, eating large quantities of food also produce the similar effect. In general, it is said in Ayurveda that if the digestive fire is strong then the time it will take to digest the food will be comparatively shorter. On the other hand, if it is sluggish and weak, it will take pretty longer time.
An Ayurvedic physician considers these different phases of Prakapa digestion for determining the exact cause of the disease.