This is the liquid part of blood that carries nutrients, hormones, and waste products throughout the body.
Growth hormone, which stimulates the growth and development of tissues, indirectly affecting the nutrient content of plasma.
After consuming food, its beneficial components are extracted through the process of digestion. This valuable substance derived from food is known as ahara rasā. Subsequently, an enzymatic activity called rasa dhatavagnī converts ahara rasā into a more finely textured form called rasa dhatu. This primary tissue in the body serves as the foundation for further growth and development.
(C. S. Su.28/4, and Su. S.S.14/3)
Essential nutrient fluid produced during digestion, gets transported around the entire body via a network of twenty-four channels or tubular structures called dhamanis, which branch off from the heart. Among these, ten pathways supply nourishment to the upper portions of the body, another set of ten pathways caters to the lower regions, whereas the remaining four vessels distribute sustenance to the sides of the torso. These distributions take place under the influence of vyanavayu, a potent life force that suffuses every corner of the human frame. (Su.sa.9)
After the process of digestion, the partially broken down food enters the small intestine, where it interacts with various cell types lining the gut wall. Over the course of approximately 48 hours, these cells absorb and utilize the nutrients present in the food, gradually becoming more distantly located from the site of initial contact. As this happens, the absorbed nutrients are stored in various locations in the body and undergo further metabolic processing before being eliminated. Unlike most tissues in the body, however, rasa dhatu has a relatively short lifespan due to rapid elimination mechanisms. After entering the bloodstream, excess rasa dhatu is quickly removed from the body through several means: urinary excretion (mutra), sweating (sweda), and defecation (purisha). These eliminatory pathways operate concurrently with the deposition and utilization of rasa dhatu, maintaining proper homeostasis and preventing excessive accumulation of this critical tissue.
Byproducts (upadhatu) of rasa dhatu are breast milk (stanya) and menstrual blood including ovum (artava), which are formed as secondary tissues from the excess or unutilized portion of rasa dhatu. [Cha. Sa. Chikitsa Sthana 15/17] [Sha. Sa. Purvakhanda chapter 5] The waste products (mala) of rasa dhatu are various secretions and discharges that are formed in this process, such as saliva, mucus, sweat, tears, etc. These are collectively called malarupakapha, as they have the characteristics of phlegm (kapha). [Cha. Sa. Sutra Sthana 28/5]
Total quantity of rasa dhatu in the body is nine anjali, which is a unit of measurement that is equal to the quantity that can be filled in a space formed by joining one’s palms together. This measurement is person-specific, as it depends on the size of one’s hands. [Cha. Sa. Sharira Sthana 7/15]
Duration required for its formation, circulation, and metabolism. According to Su. Sa. Sutra Sthana 14/14, the time span of rasa dhatu is 3015 kala, which is equivalent to five days. This means that it takes five days for the essence of food to be transformed into rasa dhatu, and then into rakta dhatu.
Rasa dhatu is the only source of nutrition for the embryo, as it is connected to the mother’s heart through the channels carrying nutrients (rasavahi). The embryo expresses its wishes to the mother through these channels, and receives the nourishment from the mother’s rasa dhatu. Rasa dhatu promotes the growth and development of the body parts, sustains the life, provides satiety, nourishes the mind, and enhances the complexion of the embryo. Rasa dhatu also nourishes the mother’s body and supports lactation. Rasa dhatu is also one of the six sources of origin of the fetus, along with the maternal and paternal factors. During embryogenesis, rasa dhatu is responsible for the formation and growth of the body parts, sustenance of life, satiety, nourishment and enthusiasm. [Cha. Sa. Sharira Sthana 3/15] [Cha. Sa. Sharira Sthana 3/24] [Cha. Sa. Sharira Sthana 6/23]
Rasa dhatu also influences the mental and emotional aspects of health. It is responsible for satiety (tushti), which is the feeling of satisfaction and contentment after eating or fulfilling a desire. It also nurtures the body (preenana), which is the feeling of comfort and care. Lastly, it nourishes rakta dhatu (raktapushti), which is the blood tissue that carries oxygen and nutrients to all parts of the body.[Su. Sa. Sutra Sthana 14/3] [Su. Sa. Sutra Sthana 15/5]
Excess consumption of heavy to digest, cold, over-unctuous food, overeating and excessive mental stress. These factors impair the digestion and metabolism of rasa dhatu and lead to its accumulation or depletion (Charaka Samhita).
When rasa dhatu is diminished, it causes degeneration or depletion of other tissues (dhatu apachaya/ksheenata), dryness of mouth (mukhashosha/rukshata), dryness or depletion of body mass (sharirashosha/rukshata), emaciation (karshya), thirst (trishna), feeling of emptiness (shunyata), tiredness (shrama), intolerance to sound (shabdaasahishnuta), pain in the heart with a feeling that someone is holding and vigorously shaking the heart (hrudayaghattana), trembling sensation of heart or tachycardia (hrutkampa), palpitation (hrutdrava) and cardiac pain (hrutshola).
Management of Rasakshaya: Nourishment therapy (tarpana) by including a variety of meat soups and juices.
When rasa dhatu is increased, it causes diminished digestive power (agnimandya), nausea (utkleshana), salivation (praseka), vomiting (chardi), lack of enthusiasm to do work (alasya), heaviness in body (gaurava), whitish discoloration of body (shvaitya), feeling of abnormal coldness of body (shaitya), looseness in body parts (angashaithilya), dyspnoea (shwasa), cough (kasa), excessive sleep (atinidrata) and fatigue or tiredness even after doing a small work (shrama/klama).
Management in Rasavriddhi: Fasting and other reduction therapies(Langhana) is the principle of treatment for the disorders due to vitiation of rasa dhatu.