Understanding cleansing process in scientific perspective

Krias, the cleansing techniques in yoga are specific processes meant to remove accumulated waste matter from the body in order to bring back and maintain optimal and harmonious functioning of physical body systems, as well as the psychological aspect.

There are 6 techniques (Shat Karma Kria) mentioned in Hatha Pradipika II.22 : Dhauti, Basti, Neti, Trataka, Nauli, Kapalabhati. Apart from these there are other also great cleansing practises such as Shanka prakshalana, Agnisara, Gajakarani.

Digestive tract is given a lot of attention in Yogic practices, in regard to what we eat, when and how much food we take in. Hand in hand go cleansing processes helping to remove unwanted substances and waste products from it to support proper functioning of digestion and thus physical and mental health as well as removing the obstacles on the path of Yoga.

In the digestive system we have what is called a gut brain, it is the second biggest group of neurons in the body after Central Nervous System (CNS). The Gut brain is directly connected to the CNS by Vagus nerve. About 90% of fibres of the Vagus nerve are delivering impulses from the Gastrointestinal tract, chest and head in to the CNS. Along the small intestine there are the biggest immune organs in the body which work together with the microbiome, that is the inner layer of the intestines.

Microbiome is connected to the brain directly through the Vagus nerve and indirectly by chemical messages from organs released to the blood which trigger reaction of Immune system.

The main functions of the gut are:

- digestion of food, creation of vitamins and non-saturated fatty acids

- participation in creating neurotransmitters

- keeping barrier between the inner space of the body and the outer space (whatever goes and is in the digestive system)

The food we take hugely affects the composition of the Microbiome. About 90 % of the bacteria consists of two groups

- Firmicutes (comes from eating fats, animal based proteins)

- Bacteroidetes (comes from eating carbohydrates, fibre)

Every individual has a unique bacterial mixture which is based on what we eat. The Appendix serves as sample reservoir of the bacterial mixture to repopulate the gut in case of an emergency situation such as heavy diarrhoea.

In predominantly plant based diet there is more of Bacteroidetes bacteria which support creation of Short Fatty Acids, which play essential role in keeping “ceasefire” among “good” and “bad” bacteria. Both types of the bacteria are needed for correct functioning of Immune system and must be held in position to balance each other.

Based on the bacterial mixture in the gut the Microbiome is asking the brain to supply more of the food from which the predominant bacteria is made of. So when we eat unhealthy foods our digestive system helps to generate cravings for more unhealthy food to keep the bacterial mixture in the Gut as it is. 1

The yogic cleansing processes affecting the digestive system:

Directly – the aim of these practices is to cleanse certain parts of the digestive apparatus

Uddyiana Bandha Kria and Nauli – supporting peristaltic movement, reduction of fat in abdominal cavity, keeping abdominal wall and diaphragm in good condition

Vaman, Danda, Vastra Dhauti – removing excess acidity, bile and phlegm from stomach

Basti – cleansing of Rectum

Indirectly – the technique involves movement of the abdominal wall

Kapalabhati – the main aim is to cleanse the lungs and frontal Sinuses. The technique involves fast inward movement of lower abdomen and complete relaxation of the abdominal wall. The movement itself stimulates the abdominal organs plus it helps to keeps the abdominal wall and pelvic floor strong and supple.

Psychological effect of Krias

Due to cultural and social habits and believes performing the Krias can be very difficult at first. To perform one of the 6 cleansing processes one has to let go of of tension in affected areas of the body. This is especially valid for the practices involving inserting something in to the body. We keep a lot of oversensitivity in the body which can lead to allergies. The Kryas are a way how to gradually reduce and hopefully completely remove the oversensitivity. Regular performance of Krias helps us in releasing certain patterns of behaviour we automatically use as reaction to specific stimuli.

Jala Neti

Pouring lukewarm saline water in one nostril and allowing it to come out by the other nostril will remove dust particles from nose, remove excess mucus, improving ability to breath. It also helps to keep clean the connections between sinuses and the nasal passage. The sinuses produce fluid which helps to clean out the space of the sinus and throw the waste in to the nasal passage. If the connecting “door” is blocked, the dirty liquid can not be passed out from sinus cavity, remains there creating painful state called sinusitis. The process of Jala Neti also cleanses olfactory nerve endings which are responsible for carrying smell sensations to the brain and thus improves the sense of smell. The water flowing though the nose also stimulates the optic nerve and helps to improve vision. It also helps to keep functioning the connection between ears and the nose.

Helpful in colds, dry or blocked nose or other respiratory troubles and psychosomatics diseases.

Limitations: pierced ear drum, this could cause water flowing into middle ear through Eustachian tube causing infection. Do Sutra Neti instead.

Sutra Neti

Inserting rubber tube in to the nose and taking it out through the mouth. This process has similar benefits as Neti done with water.

On top it helps to reused or completely remove issues with deviated septum.


Vaman Dhauti (Jala Dhauti or Dhauti HP II.23)

Drinking 1 to 1,5 L of lukewarm slightly salted water based on how much water one can take in, wait 1 to 3 minutes and than through the water out in vomiting like process. The position generally recommended is bending forward from standing position. I find there is too much pressure in the eyes, especially when done at home in the toilet bowl so I do it in squatting position.

The saline water attracts and absorbs any mucus which can accumulate in the stomach, dilutes the excess acid and also can absorb part of bile at the bottom of the stomach. By throwing the water out we get rid of all this waste. The Pancreas and Gallbladder are connected to the stomach and this washing process helps to keep the passages clear so the organs can send secretions to the stomach freely as needed for proper digestion, also preventing the build up and growth of stones in the Pancreas and Gallbladder.

The main feature of Vaman Dhauti is the removal of excess acid from the stomach. The best time to do this cleansing process is early morning, around 6:00 the excess acid is at its peak. The recommended frequency once it was learned is once every 1 or 2 weeks. If done daily it would dilute the acid in stomach to 0 so digestion could not take place.

Causes of acidity:

1/ The main cause of over acidity is mental tension (about 50%).

2/ Junk, spicy, stale & oily food, alcohol and smoking.

3/ Irregularity in meal times, which creates permanent changes in stomach causing hyperacidity.

From the water we drink about 1/2 to ¾ will come out. The rest will pass through the intestines cleaning the tract. In colon it softens the stools to prevent Piles, Constipation, Fissure making emptying of the bowels easier. In the small intestine the water gets absorbed in to blood, going to Kidneys cleaning urinary tract passing out as urine, preventing formation and growth of Kidney stones.

When throwing out the water some build up of negative emotions (anger, greed, jealousy, ...) sitting in the chest area gets released.

Too much acid in the stomach creates cravings for junk food, alcohol, smoking , ... Keeping the acid level limited helps to keep our died and weight under control.

When doing Vaman Dhauti there is a deep movement in the abdomen crating pressure also on the lungs. So along with the emptying of stomach content secretions from lungs are removed making more alveoli available for air exchange (letting out what blood brings from cells and receiving inhaled air). It cleanses the respiratory track.

Very helpful in Sinusitis, Asthma, Bronchitis

Limitations: High blood pressure, Heart Attack, Complicated duodenal ulcer, Gastric ulcer, Major abdominal or other surgery, Hernia, Menstrual problems, Pregnancy.

Temporary limitations: Acute respiratory infections, Fever

If Vaman Dhauti can not be practised drink about 500 ml warm slightly salted water in the morning and do not take food 45 minutes after.


Danda Dtauti

Drinking about 500 ml slightly salted water, swallowing the rubber tube and gently passing it down to the stomach. Bend forward and let the water come out or do Agnisara creating pump like effect helping the water to come out.

It has similar, but milder effect as Vaman Dhauti. There is significantly lover pressure on the abdomen during during the process so most of those who can not do Vaman Dhauty can perform Danda Dhauti instead.

Helpful in Hyperacidity, Biliousness, helpful to Autonomic Nervous system.


Vastra Dhauti

Swallowing a long piece of cloth about 7.7 cm wide and 6.8 m long, keep one end hanging out of the mouth!!! Do rotating Nauli and take the cloth out. The cloth can stay in the stomach maximum 20 minutes, after this time it would start to be send from the stomach to Duodenum.

Make sure to use cotton fabric. No Synthetic fibres.

The effects of Vastra Dhauti are similar as in Vaman Dhauti. Cleansing of respiratory tract is more effective.

The cloth absorbs Bile at the bottom of stomach.

It is helpful in chronic bronchitis, asthma, disease of spleen, it is said to help in 20 Kapha diseases (diseases related to excess of mucus and phlegm).



Take a cross-legged seated position, ideally Padmasana. Exhaling draw abdominal wall in, relax the abdomen fully taking a partial inhale in the process, this is the starting position. Now forcefully bring the naval inwards and than completely relax the abdomen, keep repeating this action up to 20 times. In the process fully focus on the movement of Abdominal wall, let the breath be. Breathing will happen naturally. During the technique shoulders are still, slowly learn to make the stroke from navel down, keeping the abdomen above navel relaxed.

Helps to clean the whole respiratory system, activating alveoli (the cells) in lungs to open up to receive air, keeping the capacity of lungs „elastic“ able to work in high and low demand for air. Strengthens the diaphragm, helps to oxygenate the blood.

Cleansing of sinuses. Keeping the abdominal wall in good shape, reducing fat in tissue supporting the intestines and so reducing the space the intestines occupy.

Effective in: Chronic sinusitis, Chronic Asthma, Indigestion, helps to remove Kapha originated diseases

Limitations: Ischaemic heart diseases, History of Epistaxis

Temporary limitations: pregnancy, menstruation.



Agnisara is not part of the 6 purificatory techniques, however it is a great cleansing process.

Done usually in seated position. Exhale fully drawing the navel partially inwards. Hold the breath in exhaled position, bring the navel as far forward possible with moderate speed, stay in this position 2-3 sec. Bring the navel back in to the starting position in the same moderate speed. Repeat a few times respecting ability to hold breath.

Agnisara strengthens the abdominal muscles. The movement of abdomen helps to dissolve fat around intestines, reducing tummy, creating more space for movement of diaphragm during breathing. Also helps to move the content of intestines preventing constipation. The movement of abdomen stimulates Pancreas to produce insulin, which is sent to blood controlling the sugar level. By reduction of fat Agnisara helps to reduce Insulin resistance, which in turn reduces the blood sugar level.

The procedure of Agnisara creates negative pressure in Vena Cava helping to suck the blood from legs sending it to heart for purification, making the blood circulation more effective.

The increased abdominal pressure improves the functioning of Ovaries and uterus, relieves menstrual problems.

Effective in: Chronic indigestion, chronic constipation

Limitation: High blood pressure, Hernia, Heart Attack, Surgery on the abdomen

Temporary limitations: weak abdominal muscles, pregnancy, menstruation


Uddyiana bandha Kria, Nauli

Standing with legs more than shoulder width apart, knees partially bent, place palms above the knees thumbs pointing inwards. Speedy full exhalation with the help of moving lower abdomen inward. Stop the breath in exhaled position, completely relax the abdomen and make mock (fake) inhalation. No air coming in the content of abdomen will move towards to spine and towards the chest. By expanding the thoracic cage the effect is deepened. Stay in the position until need for inhalation comes, than relax the abdomen and inhale. This is Uddyiana Bandha Kria. After being able to hold it for 15 seconds can start to learn Nauli.

To make Nauli while in the Uddyiana Bandha Kria (abdomen in concave position) below navel push the long abdominal muscle out.

Once this is done fully one can start the switching between left and right sides (creating a rotation like movement). To learn the „rotation“, in middle Nauli position reduce the pressure of left arm on the left leg for a second or two than the same on the right side. Keep repeating, eventually the full movement will happen.

It strengthens abdominal muscles.

Efective in constipation, Indigestion

Limitations: Heart attack, High blood pressure,

Temporary limitations: pregnancy, menstruation

It can also be done laying on the back, this mild version is fine also heart issues.



This Kria is for cleansing the rectum by inserting tube in to anus, adopting Utkatasana, being up to nave in water (or submerging the tube in a bowl with water) by middle Nauli creating negative pressure and drawing the water in to the rectum. Remove the tube, perform rotating Nauli in standing possition to move the water inside the body, when the uge comes expell the water out.

The benefits of Basti are removal of disorders of Spleen and other glands. Also curing of accumulation of excess water in the body (Edema or Dropsy) caused by other disorders of Vata, Pita and Kapha dosha.

The practise gives more live to the senses, internal organs, stimulates digestion and gives sense of general well being.

Effective in: constipation, gases, chronic skin diseases, chronic arthritis.

Limitations: Bleeding piles, Anal fissure



Gazing without winking at a small object with controlled mind till tears roll down is called Trataka and it is an exercise of the eyes. The ideal position for Trataka is sitting in a cross legged position with erect spine, the object of gazing being one to two arm length away at eye level.

Frequently chosen object for gazing is candle flame. The object selected for Trataka is to be free of any thought. If the object is associated with some thoughts there is great chance the mind will follow these thoughts during the gazing process instead of fully concentrating on the object. Another objects can be small black dot on white paper, Om sign, …. Another option is to look at tip of nose or middle of eyebrows. We can also gaze internally on heart, navel, middle of eyebrows.

During gazing urge to wing the eyes will come it is a part of the training to overcome this urge and keep the eyes fully opened.

The gazing is done until tears start to loll down, no fixed time limit is given. For most people it takes within 5 minutes, depending on the state of the person. If one is calm and relaxed the process takes shorter time. From my experience sometimes the eyes get very irritated and need to be closed before the tears come down. I use one of these conditions to complete the gazing.

After closing the eyes we observe the mental imprint of the flame (object), once that disappears lay down in the Savasana or sit with closed eyes for few minutes to complete the practise.

Trataka strengthens the orbital muscles, it works also as catharsis, bringing up and removing suppressed desires and wishes from subconsciousness, releasing tension bringing state of calmness and relaxation.

Effective in: weak eyesight, irritation of eye surface

Limitations: Glaucoma, Retinal detachment

Temporary limitations: It is not to be done with contact lenses, if possible also remove glasses

The cleansing practises have great benefits for harmonious function of the whole human being. The yogic texts explain them in a brief manner leaving the details to be filled by experienced teacher. Scientific studies help to clarify them and bring some proof of the effects on different parts of the body as well as psychological effects.


Written by: Zbynek Haluza (Ziggy)

3 Mar 2019


Sources of information:

1) Radkin Honzák, Psycho-somatická prvouka (2017) pg. 58-69

M.M. Gore, Anatomy and Physiology of Yogic Practices

D. Satish D. Pathak, Yoga thtough Doctors eye

Notes from lectures at Kaivalyadhama Yoga Institute, Lonavla, India