Sapta Dhatu: The Seven Tissues of the Body

The Sapta Dhatu — seven body tissues — are the structural foundation of Ayurvedic physiology. Each tissue nourishes the next in sequence, and the qualitative health of each depends on the proper nourishment of the previous one.

The seven Dhatus in order of formation are:

1. Rasa (plasma / nutrient fluid) — formed from digested food. Functions as preeti (nourishment + contentment). 2. Rakta (blood) — formed from Rasa. Functions as jeevana (life-sustenance). 3. Mamsa (muscle) — formed from Rakta. Functions as lepana (covering of the skeleton). 4. Meda (fat / adipose tissue) — formed from Mamsa. Functions as snehana (lubrication). 5. Asthi (bone) — formed from Meda. Functions as dharana (supporting the body). 6. Majja (marrow + nervous tissue) — formed from Asthi. Functions as purana (filling of the bone cavities + sensory transmission). 7. Shukra (reproductive tissue) — formed from Majja. Functions as garbhotpadana (reproduction).

Dhatu formation: the Khale Kapota nyaya. The classical analogy is of pigeons in a granary — each pigeon picks grains in sequence, eats some, leaves the rest. Similarly, each Dhatu absorbs the nutrients it needs from the previous Dhatu, and passes the remainder forward. If digestion (Agni) is weak, the early Dhatus (Rasa, Rakta) are well-nourished, but the later ones (Majja, Shukra) become depleted.

The waste products (Mala) of each Dhatu. Each Dhatu produces a metabolic byproduct: Rasa → Kapha; Rakta → Pitta; Mamsa → ear-wax, nasal secretions; Meda → sweat; Asthi → nails, hair; Majja → ocular secretions; Shukra → no waste (the final transformation).

Clinical importance. Many chronic conditions are best understood as Dhatu disorders. Anaemia is a Rakta-kshaya (depletion). Obesity is Meda-vridhi (excess). Osteoporosis is Asthi-kshaya. Infertility is often Shukra-kshaya. Neurological diseases involve Majja-vikara. Modern medicine treats each as a separate condition; classical Ayurveda traces them back to the upstream Dhatu and the digestive fire that should be nourishing it.

The seventh tissue's special quality: Ojas. From the essence of all seven Dhatus, particularly from Shukra, comes Ojas — the body's vital essence, roughly correspondable to immune resilience, vitality, and Sattva-stability. Classical texts (Charaka Sutrasthana 17/74-75) describe Ojas as "moisturous, cold, soft, smooth, viscous, sweet, stable, clear, and unctuous." It is destroyed by anger, hunger, worry, grief, exertion, fasting, and trauma. Building Ojas is the long-term goal of Rasayana therapy.

For canonical reading, the Sushruta Samhita Sutrasthana 14 and 15 ("Sonita-Varnaniya" and "Doshadhatumalakshaya-vriddhi") are the definitive texts on Dhatu physiology. AYUSH-CCRAS publishes a free annotated English translation at ccras.nic.in.