Ayurveda views digestion with a little different twist. Ayurveda is based on the five element theory, which means that all matter and energy is either one or a combination of ether, air, fire, water, and earth.

Each element is said to represent a specific kind of energy. For instance, ether (or space) is nuclear energy which represents consciousness. Air, which gives movement through the sensory and motor organs, is electrical energy. Water is chemical energy and in the body is present in plasma, cytoplasm (fluid inside cells), cerebrospinal fluid (a serum like fluid that circulates to the spaces around the brain and spinal cord), vitreous humor (clear colorless transparent jelly that fills the eyeball posterior to the lens), glandular secretions (secretions pertaining to the glands), saliva, pleural secretions (secretions found between the pleura, membrane found in the thoracic cavity), gastric mucosal secretions (secretions pertaining to the membranes in the stomach) sweat and urine. Earth is mechanical energy and is a condensed form of all the energies. It is this energy that creates structure and form in our body (bones, hair, teeth, cartilage and skin). The fire element is radiant energy. It is responsible for all bodily transformations and is responsible for all metabolic processes such as digestion, absorption and assimilation which lead to the transforming of food into tissue layers. It also regulates body temperature and creates knowledge by transforming our experiences through the senses and the mind.

Agni, or the digestive fire, is the fire element. Its radiant heat is transformed from the sun. There is also a dormant version of heat, giving “potential” fire to things like wood, the ocean, and the atmosphere. There is also fire in the human body. In fact there is agni in every cell in the body. Western nutrition refers to this as metabolism. Its main home is the stomach and is known as Jāthara agni or gastric fire. If there is a problem with jāthara agni, there will be problems with the other agnis in the body.

Agni in sanskrit means, that which “ignites”.

Dr. Lad in his book, Textbook of Ayurveda Fundamental Principles (Volume 1 pg. 84-85), explains digestion using the concept of the external preparation and cooking of food. First you need a pot (the stomach).

In it you put food (today’s ingested food) and water (digestive juices or kledaka kapha). Then you would set the pot on the fireplace (the small intestine) and add fire or heat (agni-pāchaka pitta) created by yesterday’s digested food (energy) and some air (samāna vāyu) to fan the fire. To govern this process, you would need an organizer. Prāna, your life force, serves as this organizer.

You can see the correlation to the western idea of digestion. The Ᾱyurvedic idea of agni is the “enzyme” idea of western nutrition. We need enzymes (agni) to digest any food or sensory experience. It is the samāna vāyu that helps create the movement in the stomach and small intestines (peristalsis).

Samāna Vāyu (one of the five directions prāna flows in the body) among other things is responsible for stimulating appetite and the secretion of digestive juices, peristalsis and the opening and closing of the pyloric and ileocecal valves during digestion.

Food itself has dormant prāna (life-force) and the only way we can get to it is by cooking it. Now you could cook it on a stove or in an oven and it would be considered “pre-digested”, but it takes further “cooking” (digesting) inside the body using jāthara agni for it to be available for our body to absorb. It is by the action of enzymes (western nutrition) or agni that makes it possible to digest any food or sensory experience.

Pakti in sanskrit means “digestion”. In Ayurveda, this not only means digestion of food (as referenced in Western nutrition in the forms of fat, protein and carbohydrates), but also the digestion of sound, touch, sight, taste and smell.

The digestion of food gives us new dhātus (tissues); the digestion of the perception from the sense organs gives us knowledge and understanding.

Apakti in sanskrit means abnormal digestive function or indigestion. Bloating, constipation and diarrhea as well as repressed emotions and confusion are symptoms of indigestion.

There are four varieties of agni: sama agni or balanced agni, vishama agni or irregular agni, tikshna agni or sharp agni and manda agni which means slow or dull agni.

We would all be lucky to have sama agni or balanced agni. That would mean that all your tissue layers (dhatus) would be balanced for your constitution and agni was in equilibrium, maintaining a balanced metabolism (not overweight or underweight). If you possessed sama agni, you could eat just about anything in any season and show no intolerance or adverse symptoms. In this state you would always be healthy have a strong immune system and live a long life. The mind would be clear and calm and you would live in a state of bliss….doesn’t get much better than that.

With vishama agni, your agni becomes erratic and produces irregular appetite, inconsistent digestion, indigestion, gas, constipation, and abdominal bloating. This is usually caused by aggravated vāta (the air and ether elements). Vāta can “blow the fire out” or it can “fan the fire” to make it more intense, thus the erratic nature. You may get dry skin, sciatica, insomnia and cracking joints. You may experience anxiety, fear, insecurity or mental problems. The coldness of vāta may slow down metabolism thus causing food to not be fully digested, which in turn creates ama (toxic build-up). Vata’s mobility can also speed up agni, causing diarrhea and acid indigestion. Ama buildup can be detected by the brownish color of film that coats the tongue.

Tikshna Agni or sharp agni, (hypermetabolism) is a pitta condition. Too much fire leads to a desire to eat large amounts of food frequently and have cravings for sweets. A dry throat, lips and mouth and possibly acid indigestion after eating could be experienced. Too much acid could cause hypoglycemia, diarrhea, nausea, vomiting and other inflammatory conditions to occur. One experiencing tikshna agni could become judgmental and over critical and feel anger, hate and envy.

Too much kapha dosha, the water and earth elements, which has gunas (qualities) that could be described as heavy, slow and cool, can cause agni to become dull. Kapha dosha itself has qualities just the opposite of agni. Manda agni or slow metabolism can cause a person to be unable to digest even a normal diet. This is the person who just “looks” at food and gains weight and also feels heavy, cold and may experience allergies, nausea and whose vomit may include some mucous. Obesity, high blood pressure, diabetes and edema may be signs of manda agni. Mentally, like kapha imbalances, manda agni can cause issues of greed, possessiveness and attachment. Slow metabolism causes the body to have cold and clammy skin, want to sleep more, and feel weak and lethargic, causing cravings for hot and spicy foods.

Poor diet or food combining, lifestyle choices, and uncontrolled emotions can quickly lead to imbalanced agni. When agni is aggravated, digestion is affected. Undigested food becomes ama and ama is the root cause of many diseases. The presence of ama can be seen on the tongue as a thick coating. It will appear dark brownish if agni is vishama, yellow if tikshna, and white if manda. Ama in the body may cause constipation, indigestion diarrhea, gas, bad breath, lack of taste and a confused mental state. The body becomes heavy and fatigued. It is “dis-eased”. The goal is to have sama agni, balanced and stable digestion. It is the key to experiencing good health.