Rasa Dhatu (रस धातु)

The Samskrit word 'Rasa' (रसः) has various meanings like extract/juice, taste, interest and even mercury. However in the context of human body, the word 'Rasa' used in Ayurveda refers to a body tissue or body component which is the first among 7 dhatus (धातु) described in Ayurveda. This body tissue is in the fluid form. It is formed after digestion of food as an extract of food and helps to nourish the body. It is also called as 'Ahara-rasa' (आहार-रसः) i.e. extract of food in liquid state. It performs the function of nourishing the physical body.

निरुक्तिः ॥ Etymology

Sushruta Samhita has given nirukti of the word 'rasa' as follows,

तत्र ‘रस’ गतौ धातुः, अहरहर्गच्छतीत्यतो रसः ॥ (Sush. Samh. 14.13)

tatra ‘rasa' gatau dhātuḥ, aharahargacchatītyato rasaḥ ॥ (Sush. Samh. 14.13)

Meaning: The term Rasa is derived from the root ‘gatau’ (गतौ) and it means flow or movement. Since this dhatu constantly keeps on circulating day and night in our body to provide nourishment to body tissues, it is known as rasa.

रसधातु उत्पत्ति ॥ Formation of rasa dhatu

Rasa dhatu is formed from food. We consume various type of foods which are either chewed, swallowed, drank or licked. Food in any such form undergoes the process of transformation by Agni in the stomach. Agni performs the function of digestion of this food and then that food taken from outside is transformed into a form that is acceptable by the body, so that body can utilize that for replenishment. Body can accept the food to fulfill energy demands, only if this food is available in a specific form. If the extract of the food is not in this specific form, it is called as 'Aama' (आमः) which acts like a foreign body or toxin. It can not be utilized for growth and development rather it initiates the process of development of various diseases. Thus it is highly important that, the food that a person eats, undergoes proper digestion and fluid extract of a specific form is obtained from it. Only such a food extract ultimately reaches body tissues, provides nourishment to them and called as Rasa dhatu according to Ayurveda.

रसधातोः पांचभौतिकत्वम् ॥ Panchabhoutik constitution

Rasa dhatu is obtained from food which is mostly solid or liquid. After transformation the rasa dhatu that is formed is obtained in a fluid form. Thus Prthvi (पृथ्वी | earth) and Jala (जलम् | water) element are dominant in Rasa dhatu.

रसधातोः स्थानम् ॥ Location of Rasa dhatu

Rasa dhatu circulates through channels and a network system known as Rasavaha srotas (रसवह स्रोतस). However it is mainly located in Hrudayam (हृदयम्) which is also the chief site of Manas (मनः) and Prana (प्राणः). From this site, Rasa dhatu is distributed all over the body through various dhamanis (धमन्यः | vessels).

रसधातोः कार्यम् ॥ Function

Rasa dhatu is formed as as extract of food. And thus, it acts as a food for rest of the body tissues. Nourishment is the main function performed by it. Various function performed by rasa dhatu are listed below,

1. Prinana (प्रीणनम्) / Tarpana (तर्पणम्): Nourishment of the whole body

1. Vardhana (वर्धनम्): growth and development of body tissues

1. Satiety (तुष्टिः) : Rasa dhatu is responsible for and associated with the feeling of satiety which is physical as well as a psychological aspect of a human being.
2. Nourishing Rakta dhatu (रक्तपुष्टिः) : Part of Rasa dhatu undergoes further transformation to generate rakta dhatu and nourish the existing one.

रसधातोः उपधातवः॥ Upadhatu of Rasa dhatu and their function

Rasa dhatu when subjected to the process of micro-transformation (सूक्ष्मपचनम्), it generates 2 more entities which are known as Upadhatus (उपधातु) of Rasa dhatu. Ayurveda Acharya have opined that Raja (रजः) or Artavam (आर्तवम्) equivalent to menstrum and ovum is one upadhatu of rasa dhatu. Stanya (स्तन्यम्) i.e. breast milk of a lactating woman is the second upadhatu of Rasa.

रसधातोः मलम् ॥ Mala of Rasa dhatu

During the micro-transformation of Rasa dhatu inside body and formation of upadhatus, some fluid secretion is generated as a waste byproduct and it is called as ‘kapha’ (कफः). However, this is waste or unwanted kapha which resembles Kapha dosha. Thus, Kapha dosha is closely associated with rasa dhatu. The clinical features of increase in rasa levels of body are similar to those of kapha dosha increase.

रसधातोः स्रोतसम् ॥ Site of metabolism and Channel of transport

Rasa dhatu undergoes metabolic transformation in the network system or channel known as Rasavaha srotas. Mahasrotas (महास्रोतसम् | similar to gastrointestinal tract) and hridayam (हृदयम्) are the 2 chief organs of Rasavaha srotas. Rasa dhatu is formed in Mahasrotas and then reaches upto hrudayam.

रसधातुदुष्टिहेतवः ॥ Vitiating factors

The dietary, lifestyle factors that directly affect rasa dhatu and its function are listed as below. (Cha vi 5/13)

1. Repeated intake of heavy to digest food
2. Intake of food or drinks that are very cold
3. Intake of food that has excess fat content
4. Overeating
5. excessive mental stress and over thinking

Rasa Sara purusha characteristic

तत्रस्निग्धश्लक्ष्णमृदुप्रसन्नसूक्ष्माल्पगम्भीरसुकुमारलोमासप्रभेवचत्वक्त्वक्साराणाम्| सासारतासुखसौभाग्यैश्वर्योपभोगबुद्धिविद्यारोग्यप्रहर्षणान्यायुष्यत्वंचाचष्टे||१०३|| cha vi 8/103

In persons who are tvaksara (having constitutional essence of skin), the skin is unctuous (snigdha), smooth (shlakshna), soft (mridu), clean and adorable (prasanna) with fine (sukshma), thin (alpa), deep rooted (gambhira) and delicate (sukumara) hairs and is lustrous (prabha). This essence indicates happiness, good fortune, power, enjoyment, intelligence, knowledge, health, cheerfulness and longevity.

Importance of Rasa dhatu in health and wellbeing

रसजं पुरुषं विद्याद्रसं रक्षेत् प्रयत्नतः |

अन्नात्पानाञ्च मतिमानाचाराञ्चाप्यतन्द्रितः ||१२|| (Su su 14/12)

The existence of purusha depends upon rasa. Therefore, one should protect and maintain the quality and quantity of rasa dhatu with utmost care.[Su. Sam. Sutra Sthana 14/12] It can be achieved through proper diet and lifestyle.

Rejuvenating therapy (Rasayana) is a special branch of Ayurveda dealing with the promotion and preservation of health. It helps in maintaining the best qualities of rasa dhatu and other body components. The quality of rasa is directly responsible for the quality of other tissues, immunity, promoting health and longevity. [Dalhana, Su. Sa. Chikitsa Sthana 27/1]

रसनिमित्तमेव स्थौल्यं कार्श्यं च | (su su 15/32)