Most people would define indigestion as the temporary inconvenience or discomfort that arises from eating too much food or eating foods that are too rich or spicy for our digestive process to handle. This description tends to place the focus more on the symptoms of indigestion than the process itself. Ayurveda offers a much more specific and comprehensive definition. It states that indigestion is both the inability to transform and assimilate food and the inability to eliminate metabolic waste products that result from the digestive process. Several things occur as a result of poor digestion.
First, ama forms in the G-I tract. Ama is the food which remains in the gastrointestinal tract in undigested form. It is different from mala, which, as we defined earlier, is the natural, unusable waste-product resulting from healthy metabolism. If the toxic sticky residue of incomplete metabolism (ama) is not quickly burned up by the digestive fire, it will accumulate in the G-I tract.
When ama becomes too plentiful in this area, it will naturally be removed by the doshas and transported to the dhatus by the action of dosha gati — the twice-daily movement of the doshas from the G-I tract to the deeper tissues of the body. Once ama is deposited in the dhatus, it begins a chain of events that debilitates them and impairs their function. This results in a weakened immune system that makes the dhatus susceptible to infection and degenerative disease.
Second, ama interferes with or “spoils” the functioning of the doshas, leading to a breakdown in their coordination. This dysfunction especially disturbs or depletes the strength of the digestive agni, in the form of pachak pitta, which becomes responsible for the creation of even more ama — undigested food stuff.
Third, when digestion is impaired, nutritional products are not available to nourish the dhatus. Metabolism and assimilation of nutrients for dhatu development happens sequentially. When the refinement process breaks down in one stage, all succeeding stages are adversely affected.
Fourth, the natural doshic processes that eliminate mala get disturbed. As a result of an imbalance in vata funcrioning caused by ama, metabolic waste products can no longer be properly removed from the dhatus and carried back to the G-I tract for elimination. This accumulation of waste further weakens and damages the dhatus.
Lastly, the ama and mala which have accumulated block the dhatus ability to assimilate food and medicine, so it becomes difficult for them to regain their healthy status. Ama can remain in the dhatus for years, and tends to accumulate in those dhatus which are congenitally weak or have been most damaged by ama’s influence in the past.
All these factors contribute to the dhatus’ impaired functioning and constitute the root cause of most degenerative diseases. The extensive diagnostic techniques available to an Ayurvedic physician allow him to locate in which dhatus the ama has been deposited, and the extent of the dysfunction and physical damage. Diagnosis also pinpoints the imbalances in the digestive process which were responsible for producing the ama in the first place. We will discuss this later in the chapter, after we have elaborated on the Ayurvedic understanding of the two phases of digestion.
TWO PHASES OF DIGESTION
Ayurveda explains that digestion occurs not only in the gastrointestinal tract but in the dhatus as well, and makes a clear distinction between these two different metabolic processes. The conversion that takes place in the gastrointestinal tract, up to and including absorption through the intestinal walls, is called prapa-ka digestion. This initial stage of digestion prepares the food we eat to be assimilated by the dhatus in the next seven metabolic stages, known collectively as vipaka digestion, the post-absorptive digestive processes.
PRAPAKA METABOLISM: DIGESTION IN THE G-I TRACT
Recall in our discussion of the doshas that the gastrointestinal tract and the area surrounding it is divided into three sections according to the dosha-specific functions which govern that area. The upper part of the G-I tract is dominated by the cohesive, liquefying and lubricating functions of kapha dosha; the middle zone by the transformative actions of pitta dosha and the lower section by the drying, separating and absorptive processes of vata dosha.
Each of these zones actively participates in the first or prapaka st.ige of digestion.Prapaka digestion begins with eating and swallowing. As the food moves through the G-I tract, jathara agni causes it to undergo a fixed sequence of metabolic actions which are determined by the specific functions of the zone in which they are occurring. These three stages of prapaka digestion are referred to as the three transient phases of metabolism.
Three Phases of Prapak (Transient) MetabolismPrapak Metabolism – Dosha Zone – Taste – Function
Madhur – Kapha – Sweet – Moistening of food
Amla – Pitta – Sour – Conversion of food
Katu – Vata – Pungent – Absorption and Separation of food
Another important point to remember from Chapter Three is that each dosha has associated with it a dominant taste or rasa. The inherent natures of the five elements and their combinations give rise to six basic tastes: sweet, sour, salty, bitter, pungent and astringent. However, when the elements specifically combine to form the doshas in the body, they give rise to a taste characteristically associated with that particular dosha.
When the water and earth elements combine to form kapha dosha, a sweet taste is always created. Keep in mind that when Ayurveda refers to the sweet taste associated with kapha, they are not talking about the highly concentrated sweetness found in foods made with refined sugars. The taste inherent to the nature of agni bhuta is sour, which makes the taste associated with pitta dosha predominantly sour. When akash and vayu combine to form vata dosha, they form a primarily pungent taste.
What is the significance of taste to prapaka digestion? As food moves through the three dosha-specific stages of prapaka, or transient digestion, it takes on the taste associated with the dosha governing that particular zone. The influence of jathara agni will first cause the whole food mass to be converted to a predominantly sweet taste in the kapha zone, then to a sour taste in the pitta zone and finally to a pungent taste in the vata zone. These basic tastes will predominate regardless of the taste the food has at the time it was eaten.
When we eat food, it first enters the kapha zone, the first stage of transient metabolism, where it gets moistened and liquefied. Because of the abundance of watery secretions in this zone, the food also increases in volume. Even if the food mass contains all six tastes, it acquires a predominantly sweet taste, and foods that already have a sweet flavor will become even sweeter in this initial phase of prapaka digestion.
As the food moves into the second phase of transient digestion in the mid-zone, agni’s qualities begin to take over. Temperature rises due to the conversion process taking place. The particles of food which were bound together and liquefied by kapha’s action now mix with acid secretions from glands in the pitta zone. They are broken down and homogenized and can no longer be recognized as distinct particles of food. As a whole, the food mass takes on the sour taste associated with pitta dosha.
During the final stage of transient metabolism, the transformed food mass enters vata territory, where absorption begins. Under vata’s influence, the food’s nutrient portions are separated from the parts that can’t be used. In this process, jala (water) gets separated from prithvi (earth) and, as a consequence, the food mass decreases in volume. Though jathara agni is still active in this last phase of prapaka digestion, the food mass becomes largely pungent in taste, a quality of vata that is due to the absence of the water element.