Is Shanka Prakshalana Safe?

I’ve been asked that question many times, and up until now Ive only been able to give an answer based on theory and on my professional and personal experience with this colon cleansing technique. (If youre not familiar with shanka prakshalana, see my explanation here.)

By theory, dangerous shifts in blood levels of sodium and potassium could result in serious health consequence. By professional and personal experience, I can say Ive never seen it happen, not in hundreds of trials. Of course, just because I havent seen it, that doesnt mean serious electrolyte shifts won’t occur depending on individual circumstances.

As a physician and a scientist, I’ve wished for a research study documenting the safety of shanka prakshalana, real data to support its safety and efficacy. This week I finally located just such as study, and I am happy to share it with you today.

In 1978, quite a long time ago, a physician on an Air Force Base in the Midwest of the United States, Colonel Clint Chambers, designed a study along with a Texas colleague of his, Gray Carter, to look at the ability of bowel irrigation with salt water to prepare the large intestine for colonoscopy or surgery. They werent yogis, at least as far as I know, and I dont imagine either of them had heard the term shanka prakshalana. They based their trial on the textbook theories of how the sodium ion of common table salt (sodium chloride) traverses the gut wall, and they were aware of two prior studies looking at a similar bowel prep tried due to the same deductive reasoning.

Twenty-three patients were cleansed with a physiological solution of salt water, the exact solution recommended for shanka prakshalana. Its the same 0.9% sodium chloride we put into the veins of dehydrated patients in the hospital, but it was administered either by mouth or by a tube into the stomach.

Electrolytes were measured prior to the ingestion of salt water and immediately thereafter. No significant shifts of sodium or potassium were observed.

Doctors judged the efficacy of warm salt water at thoroughly cleansing the colon. Most of the time they gave an excellent rating, and it was at least satisfactory 95% of the time for all patients in this study, inclusive of another set of 14 patients who were given a little potassium and bicarbonate in their salt solutions. That success rate parallels, or even exceeds, any modern pharmaceutical colon cleanse preparation for colonoscopy.

Dr. Chambers and Dr. Carters results are consistent with a previous study in 1976 in which 37 people were given a plain table salt solution as a colon cleansing preparation. After drinking four liters of physiological saline, none of the patients had significant electrolyte shifts. In 1975, Dr. Crapp (really, Im not making that up) and his colleagues successfully cleaned the colons of 47 people with physiological saline. They didnt report any electrolyte abnormalities either.

So why, you may be asking, if shanka prakshalana is such a safe and effective natural method of colon cleansing, did the medical establishment abandon it in favor of other solutions?

The doctors in the 1978 study gave up on asking the patients to drink salt water after a few of them had a difficult time with the taste and volume of liquid needed. It was too salty to enjoy, and it induced vomiting in two. Instead they moved to placement of a tube that is threaded up the nose, down the back of the throat, and then into the stomach with the liquid infused through it. For some reason, the patients apparently liked that better, although having a tube up your nose is not too fun either.

Subsequent studies revealed the dangers and side effects of nasogastric tube placement, and eventually the whole saline irrigation technique of bowel preparation was deemed intolerable by patients. A pharmaceutical company immediately stepped in to make a solution that works by the same physiological principles of the salt flush without the extreme salty taste. That solution, polyethylene glycol or PEG, is still used for colonoscopy preparations today. Marketing and patient satisfaction with PEG left simple saline flushes to disappear from the conversation. Shanka prakshalanas attempt to become mainstream was thwarted, and its trials have been buried in dusty journals from the 1970s.

So, I am happy to be able to say that shanka prakshalana is a safe method for colon cleansing for most people based both on my professional experience and on the scientific literature. I have never found a case report or study indicating otherwise. Still, a theoretical basis for injury exists, and susceptible people should either avoid its use or exercise extreme caution under the direction and care of their personal physician. Anyone with kidney disease, congestive heart failure, high blood pressure or taking medications for high blood pressure, ischemic heart disease, stomach ulcers or pregnancy is at a higher risk of complications.

Shanka prakshalana should never be done at home alone without at least one family member or buddy to keep an eye out, and the first experience should be done under the care and observation of an experienced practitioner.

If you want a safe and natural method of intestinal cleansing for colonoscopy, discuss salt water flushing with your doctor. Below are the scientific references for the articles mentioned above for you to share with your healthcare team.


  1. Chambers CE, Carter HG. Saline lavage: a rapid, safe, effective method of whole-gut irrigation for bowel preparation. South Med J. 1978 Sep;71(9):1065-6. PDF (162 KB)
  2. Levy AG, Benson JW, Hewlett EL, Herdt JR, Doppman JL, Gordon RS Jr. Saline lavage: a rapid, effective, and acceptable method for cleansing the gastrointestinal tract.Gastroenterology. 1976 Feb;70(2):157-61.
  3. Crapp AR, Tillotson P, Powis SJ, Cooke WT, Alexander-Williams J. Preparation of the bowel by whole-gut irrigation. Lancet. 1975 Dec 20;2(7947):1239-40.

How to Lose Weight with Yoga

At the Yoga Institute in Mumbai, the city formerly and still defiantly called Bombay by many of its residents, I attended a seminar on Yoga for weight management.

The words of the current president, Dr. Jayadeva Yogendra, who is the son of the legendary founder, Shri Yogendra, reflect the inherent wisdom of the discipline.  “Yoga is another word for a way of living, where one gives as much importance to happiness and peace of mind as to one’s material comforts.”

It is through attending to one’s entire way of living, with patience and with hope, that we confront our desires for comfort foods and tame our minds’ tendency to convince us that we’re better off eating Doritos on the couch instead of taking a walk through the timber.

Our minds play a huge role in weight management.  We eat when we’re stressed.  Yoga lowers stress.

We eat for other reasons too and not always just because we’re hungry.  Why do we reach for that piece of chocolate cake after dinner when we’re already full?

Yoga quiets the mind and helps one to reflect with wisdom from a higher perspective, from the witness inside of us who watches everything we do and wants to help us make the best choices.

When it comes to food, Yoga lore makes it clear that the best choice is a wholesome vegetarian diet.  Eat lots of fruits and vegetables with whole grains.  The instructor for the day was emphatic about avoiding the five “whites.”  Eat no refined sugar, no refined white flour, no ghee (clarified butter), no cheese, and drink no milk.

Our attitude towards food should be one of reverence.  What we eat is an offering to the Divine, made at the temple of our bodies.   Keep a food diary of your offerings and reflect of what you’ve been feeding Spirit.

Of course, Yoga is a set of physical exercises as well.  Depending on what style of Yoga you choose, you can burn many calories or hardly any.  For the slower, more meditative styles of Hatha Yoga, the benefit comes from awakening the tissues with their stretch, increasing vitality and energy, and motivating one for more strenuous aerobic exercise.

And here’s one last tip from the teachers at the Yoga Institute.  Performing surya mudra helps to increase metabolism and thereby promotes weight loss.  Place the tip of the ring finger at the base of the thumb, hands resting on the knees or thighs, while sitting quietly with eyes closed for five to fifteen minutes.  According to them, this completes a circuit between the earth and fire energy channels, igniting and burning the elements.

Whether there is a subtle energy effect or not is unclear by western science standards, but for sure taking the time to quiet the mind just before eating will lead to the proper state to eat with reverence and awareness.  Or you can try it after the meal and before that piece of chocolate cake to reflect on whether you REALLY want it as a part of your body after that brief spot on your taste buds.


Fasting for Health

Since I last posted about the benefits of fasting for health, more supporting evidence has been found. As these four studies show, there seems to be something important happening when we go for a period of time without calories.

Fasting may lower the risk of heart disease. 200 patients undergoing a cardiac cath to get an angiographic image of the arteries of their heart were asked whether or not they fast occasionally. Those who said they did had a 58% lower risk of having blocked arteries than those who did not. Although this study, presented as an abstract at the recent American College of Cardiology meeting, doesnt prove cause and effect, its an interesting association that may be explained by changes in metabolism that occur with occasional fasting things like levels of growth hormone, an agent that gets released when theres little food intake. Growth hormone triggers the body to burn fat and protect muscle mass. Read about the study here.

Fasting protects the brain and spinal cord. In a model of spinal cord trauma that involves loss of function of the legs, eating every other day, whether initiated before or after injury, promotes re-growth of nerves and the recovery of movement. Simply restricting the usual calories eaten every day to 75% of usual does not have the same effect.  That means its not about the number of calories, its about giving your body a break from the constant ingestion of food. (Jeong MA et al. Intermittent fasting improves functional recovery after rat thoracic contusion spinal cord injury. J. Neurotrauma Mar;28(3):479-92, 2011.)

Fasting can slow aging and ward off dementia. In mice that are genetically programmed to have a shorter lifespan, fasting every other day corrected specific protein deficits in the brain. The replenished proteins are important contributors to brain cell survival and growth.  (Tajes M et al. Neuroprotective role of intermittent fasting in senescence-accelerated mice P8 (SAMP8). Exp Gerontol. Sep;45(9):702-10, 2010.)

Fasting doesn’t interfere with athletic performance. Lots of people around the world fast for religious or cultural reasons. During Ramadan, for example, people fast when the sun shines (often up to 18 hours) every day for one month. Studies of fasting athletes show little evidence of decreased performance. Any effects are quite small and may be related more to sleep deprivation since all eating must occur during night-time hours.  (Maughan RJ, Fallah J, and Coyle EF. The effects of fasting on metabolism and performance. Br J Sports Med. Jun;44(7):490-4, 2010.)

Fasting helps with weight loss. The latest review of existing evidence for the effects of intermittent fasting (IF) indicate it is just as effective as reducing the overall amount of calories eaten on a daily basis when it comes to losing weight. The great part about IF though is that on non-fasting days dieters eat whatever they want without restricting quantity and they dont lose lean muscle mass. That makes limiting calories a lot more enjoyable and healthy. (Varady KA. Intermittent versus daily calorie restriction: which diet regimen is more effective for weight loss? Obes Rev. 2011 Mar 17. doi: 10.1111/j.1467-789X.2011.00873.x.)

I’m a fan of intermittent fasting (IF). Every other evening eat an early dinner, between 5:00 and 6:00 in the evening, then skip breakfast in the morning, and eat lunch around noon. That makes for an 18-hour fast, essentially the window of time needed for our metabolic machinery to reset to maximum efficiency without detrimental effects. An IF schedule such as this fits with the advice of ancient Yoga gurus as written in the Gheranda Samhita.