Ayurvedic Concept of Metabolism – Nyayas Related to Nutrition

By Dr. Regina Antony
Acharya Chakrapanidatta, in his commentary on Charaka Samhita, explained how the Dhatus form and get nourished in a sequential order. This is also called Dhatu Poshana Nyaya.
There are three theories that explain how the Dhatus form and get nourished. They are 

1. Ksheera dadhi Nyaya – Theory of transformation
2. Kedara kulya Nyaya – Theory of transmission
3. Kale kapota Nyaya – Theory of selection
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Ksheera dadhi Nyaya – Theory of transformation

Ksheera = milk,
Dadhi = curd.
According to this theory, the first Dhatu formed as a result of digestion of essence part of food (Ahara rasa) by Dhatvagni is entirely converted into the succeeding Dhatu.
It means the Rasa Dhatu that is formed gets totally transformed into Rakta Dhatu; Rakta Dhatu gets completely transformed into Mamsa Dhatu and so on.
This is compared to the conversion of milk (ksheera) into curd (dadhi) in entirety.
This complete transformation of one Dhatu to another is called Sarvatma Parinama (total bio-conversion).

– According to this theory, the entire rasa dhatu gets converted into rakta dhatu; the entire rakta dhatu into mamsa dhatu and so on upto shukra dhatu by the 7^th or 30^th day.
So if a person fasts for 7 days, he should either have only shukra dhatu in his body or he should die owing to the lack of dhatus other than shukra dhatu. But that doesn’t happen even if a person fasts for 30 days.

– According to this theory, if the rasa dhatu that is formed is defective, all the other dhatus should also be defective. For example, an increase in fat tissue should cause an increase in bone tissue, but it is not true.

– This theory cannot be applied in case of certain medicines such as rejuvenating and aphrodisiac drugs as they have specific action on a specific tissue.
Milk is an aphrodisiac and has a direct and immediate action over the reproductive tissue. But this action of milk cannot be explained by Ksheera dadhi nyaya. According to this theory, milk will take 30 days to act upon the shukra dhatu and bring about a result.
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Kedara kulya Nyaya – Theory of transmission

Kedara = paddy fields,
kulya = canal.
According to this theory, nourishment of the tissues can be compared to irrigation of fields by water from a canal. The water from a canal first irrigates the field nearest to it, followed by the other fields in the area through which it passes.

Since Rasa Dhatu is nearest, the essence part of food reaches it through the channels of Rasa and nourishes it. After nourishing the Rasa dhatu by the action of Rasa Datvagni, the essence part of food nourishes the next Dhatu, i.e. the Rakta Dhatu. In this manner, the essence part of food (Ahara rasa) circulates from one tissue to the next and nourishes them.

– From this theory it is clear that Dhatus obtain nutrition from the essence part of food (Ahara rasa) through channels meant to transport nutrients (dhatuvaha srotases).
– It also clarifies the fact that specific dhatus get nourished by specific parts of the Ahara rasa (Dhatu poshaka amsha).
– It also indicates that rasa dhatu gets nourished faster than mamsa dhatu as it is nearer to the channels of nutrition.
– This theory can explain the quick aphrodisiac action of milk on the reproductive tissue (shukra dhatu).
– It is also clear that an increase of fat tissue need not cause an increase in bone tissue.
Read related – Dhatu – 7 Body Tissues As Explained In Ayurveda

Kale kapota Nyaya – Theory of selection

Kale = threshing floor
Kapota = pigeon.
Like pigeons pecking the grains from a threshing floor and carrying it back to their nests depend on the direction and the time required for them to travel, the nutrition required by a Dhatu is selected from the essence part of food which contains all the nutrients and the order of nutrition depends on the order of the Dhatus.
Here, the field indicates the essence part of food and the pigeons indicate the body tissues.

This theory explains that the individual Dhatvagnis select the required nutrients from the essence part of food which contains all the nutrients.
The nutrients are transported through channels (srotas). Since Rasa Dhatu is the nearest, it gets nourished first.
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– From this theory it is clear that the replenishment of tissues is a uniform sequential process.
– This theory can explain the quick aphrodisiac action of milk on the reproductive tissue (shukra dhatu).
– It is also clear that an increase of fat tissue need not cause an increase in bone tissue.
– It is also not necessary that a vitiated tissue need not vitiate the next tissue.

All these three theories are considered important as a single theory cannot explain the nourishment of tissues. These theories are equivalent and do not oppose each other.

Thus it can be concluded that Ahara rasa reaches the channels of nutrition according to Kedari Kulya Nyaya,
nutrients in these channels are selected by a particular Dhatu based on its requirements according to Kale Kapota Nyaya and
the nutrients are transformed into Dhatus according to Ksheera Dadhi Nyaya.