Rasa Dhatu (रस धातु)
The Samskrit word 'Rasa' has various meanings like extract/juice, taste, interest and even mercury. However in 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 described in Ayurveda. Dhatus are building blocks of physical body called as Sharira. It is also called as 'Ahara-rasa' i.e. extract of food in liquid state. It performs the function of nourishing the physical body.
Nirukti
तत्र ‘रस’ गतौ धातुः, अहरहर्गच्छतीत्यतो रसः ||१३|| (Su su 14/13)
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 is digested by Agni in the stomach. Agni performs the function of digestion of this food and its transformation into a form that is acceptable by the body. To make this food bio-available foe all the body tissues a uniform microfine extract of this food is formed by Agni. This food extract which ultimately reaches body tissues, provides nourishment to them is called as Rasa dhatu according to Ayurveda.
Panchabhoutik constitution
Rasa dhatu is formed from Food and is in liquid form. Thus Prthvi (earth) and Jala (water) element are dominant in Rasa dhatu. (Dwarkanath C. Introduction to Kayachikitsa. Chaukhambha Orientalia. Varanasi; 1996. Third edition.pg.320)
Location of Rasa dhatu
The location or seat of Rasa dhatu is said to be Hridayam. (Su. Su 14/3) Hridayam is located between nabhi (umbilicus) and neck, the region which is identified as Ura (chest) region. From this site, Rasa dhatu is distributed all over the body through vessels.
Function
The functions attributed to rasa dhatu are:
- Tarpana: nourishment of body at any age.
- Vardhana: growth and development (especially in kids)
- Dharana / jeevana: stabilizing and maintaining the dhatu (during middle age)
- Yapana: preventing the total deterioration of dhatu (during old age)
Other functions like stabilizing the body components(avashtambhana), unction(snehana) are also carried by rasa dhatu.[Su. Sa. Sutra Sthana 14/3]
It is responsible for satiety(tushti), nurturing body(preenana), nourishing rakta dhatu(raktapushti).[Su. Sa. Sutra Sthana 15/5]
Upadhatu of Rasa dhatu and their function
Breast milk(Stanya) and menstrual blood including ovum (artava) are formed as metabolic byproducts(upadhatu) of rasa dhatu.[Cha. Sa.Chikitsa Sthana 15/17]. Sharangadhara considers only breast milk(stanya) formed as upadhatu. [Sha. Sa. Purvakhanda chapter 5].
Various secretions and discharges are formed in this process as ‘kapha’. This is termed as "malarupakapha".
Associated Dosha
Kapha dosha is formed during metabolic transformation happening in Rasa dhatu. It is formed as mala of rasa dhatu. 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. On the other hand, clinical features of lower rasa levels in body resembles with increase in vata levels of body.
Associated Srotas
Rasa dhatu undergoes metabolic transformation in the system or channel known as Rasavaha srotas. Mahasrotas (similar to gastrointestinal tract) and hridayam are the 2 chief organs of Rasavaha srotas. Rasa dhatu is formed in Mahasrotas and then reaches upto hridayam.
Vitiating factors
The dietary, lifestyle factors that directly affect rasa dhatu and its function are listed as below. (Cha vi 5/13)
- Repeated intake of heavy to digest food
- Intake of food or drinks that are very cold
- Intake of food that has excess fat content
- Overeating
- 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)