Should You Sit, Squat, or Lean During a Bowel Movement?

Compared to rural African populations eating traditional plant-based diets, white South Africans and black and white Americans not only have more than 50 times the heart disease, 10 times more colon cancer, and more than 50 times more gallstones and appendicitis, but also more than 25 times the rates of so-called pressure diseases—diverticulitis, hemorrhoids, varicose veins, and hiatal hernia.

Bowel movements should be effortless. When they’re not, when we have to strain at stool, the pressure may balloon out-pouchings from our colon, causing diverticulosis, inflate hemorrhoids around the anus, cause the valves in the veins of our legs to fail, causing varicose veins, and even force part of the stomach up through the diaphragm into our chest cavity, causing a hiatal hernia, as I covered previously. When this was first proposed by Dr. Burkitt, he blamed these conditions on the straining caused by a lack of fiber in the diet, but did acknowledge there were alternative explanations. For example, in rural Africa they used a traditional squatting position when they defecated, which may have taken off some of the pressure.

For hundreds of thousands of years, everyone used the squatting position, which may help by straightening the “anorectal angle.” There’s actually a kink right at the end of the rectum, almost a 90-degree angle that helps keep us from pooping our pants when we’re just walking around, but that angle only slightly straightens out in a common sitting posture on the toilet. Maximal straightening out of this angle occurs in a squatting posture, potentially permitting smoother bowel elimination. (I remember sitting in geometry class thinking, “When am I ever going to use this?”; little did I know I would one day be calculating anorectal angles with it—stay in school, kids.)

So how did they figure this out? They filled latex tubes with a radiopaque fluid, stuck them up some volunteers, took X-rays with their hips flexed at various angles, and concluded that flexing the knees towards the chest, like one does squatting, may straighten that angle and reduce the amount of pressure required to achieve emptying of the rectum. But it wasn’t put to the test until 2002, when researchers used defecography, which are X-rays taken while the person is defecating, in sitting and squatting positions.  And indeed, squatting increased the anorectal angle from around 90 degrees all the way up to about 140.

So, should we all get one of those little stools for our stools, like the squatty potty that you put in front of your toilet to step on? No, they don’t seem to work. The researchers tried adding a footstool to decrease sitting height, but it didn’t seem to significantly affect the time it took to empty one’s bowels or significantly decrease the difficulty of defecating. They tried even higher footstools, but people complained of extreme discomfort using them. So, nothing seemed to compare with actual squatting, which may give the maximum advantage, but, in “civilized” countries, it may not be convenient. But, a similar effect can be achieved if you lean forward as you sit, with your hands on or near the floor. They advise all sufferers from constipation to adopt this forward-leaning position when defecating, as the weight of your torso pressing against the thighs may put an extra squeeze on your colon.

But instead of finding ways to add even more pressure, why not get to the root of the problem? The fundamental cause of straining is the effort required to pass unnaturally firm stools. By manipulating the anorectal angle through squatting or leaning you can more easily pass unnaturally firm stools; but why not just treat the cause? And eat enough fiber-containing whole plant foods to create stools so large and so soft that you could pass them effortlessly at any angle. Cardiologist Dr. Joel Kahn once said you know you know you’re eating a plant based diet when “you take longer to pee than to poop.”

But seriously, even squatting does not significantly decrease the pressure gradient that may cause hiatal hernia. It does not prevent that pressure transmission down into the legs that may cause varicose veins. And this is not just a cosmetic issue. Protracted straining can cause heart rhythm disturbances, reduction in blood flow to the heart and brain, sometimes resulting in defecation-related fainting and death. 15 seconds of straining can temporarily cut blood flow to the brain by 21%, cut blood flow to the heart nearly in half, thereby providing a mechanism for the well-known bedpan death syndrome. You think you have to strain sitting; try having a bowel movement on your back. Bearing down for just a few seconds can send your blood pressure up to nearly 170 over 110, which may help account for the notorious frequency of sudden and unexpected deaths of patients while using bedpans in hospitals. Of course, hopefully, if we eat healthy enough, we won’t end up in the hospital to begin with.

To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by Katie Schloer.

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• G J Davies, M Crowder, B Reid, J W Dickerson. Bowel function measurements of individuals with different eating patterns. Gut. 1986 Feb;27(2):164-9.
• D Raahave. Faecal retention: a common cause in functional bowel disorders, appendicitis and haemorrhoids--with medical and surgical therapy. Dan Med J. 2015 Mar;61(3). pii: B5031.
• B A Sikirov. Primary constipation: an underlying mechanism. Med Hypotheses. 1989 Feb;28(2):71-3.
• R E Tagart. The anal canal and rectum: their varying relationship and its effect on anal continence. Dis Colon Rectum. 1966 Nov-Dec;9(6):449-52.
• D Sikirov. Comparison of straining during defecation in three positions: results and implications for human health. Dig Dis Sci. 2003 Jul;48(7):1201-5.
• S S Fedail, R F Harvey, C J Burns-Cox. Abdominal and thoracic pressures during defecation. Br Med J. 1979 Feb 3;1(6159):344.
• S Rad. Impact of ethnic habits on defecographic measurements. Arch Iranian Med 2002; 5 (2): 115-117.
• J McGuire, R S Green, S Courter, V Hauenstein, J R Braunstein, V Plessinger, A Iglauer, J Noertker. Bed Pan Deaths. Trans Am Clin Climatol Assoc. 1948;60:78-86. No abstract available.
• A Benchimol, T F Wang, K B Desser, J L Gartlan Jr. The Valsalva maneuver and coronary arterial blood flow velocity. Studies in man. Ann Intern Med. 1972 Sep;77(3):357-60.
• J C Greenfield Jr, J C Rembert, G T Tindall. Transient changes in cerebral vascular resistance during the Valsalva maneuver in man. Stroke. 1984 Jan-Feb;15(1):76-9.
• A Martin, w Odling-Smee. Pressure changes in varicose veins. Lancet. 1976 Apr 10;1(7963):768-70.
• J E Santos, G D’Ippolito, L M Leme, A Sanuda, D C Shigueoka, J Szejnfeld. Avaliação do ângulo ano-retal por meio de defecograma em voluntárias assintomáticas nulíparas e multíparas. Radiol Bras vol.36 no.4 São Paulo July/Aug. 2003 . (In Portuguese)
• D P Burkitt. Varicose veins, deep vein thrombosis, and haemorrhoids: epidemiology and suggested aetiology. Br Med J. 1972 Jun 3;2(5813):556-61.
• D P Burkitt. Dietary fibre and 'pressure diseases'. J R Coll Physicians Lond. 1975 Jan;9(2):138-46. No abstract available.
• A Y Kim. How to interpret a functional or motility test - defecography. J Neurogastroenterol Motil. 2011 Oct;17(4):416-20. doi: 10.5056/jnm.2011.17.4.416.
• W N Kapoor, J Peterson, M Karpf. Defecation syncope. A symptom with multiple etiologies. Arch Intern Med. 1986 Dec;146(12):2377-9.

Images thanks to Shawn Campbell via Flickr.

• Africa
• African Americans
• appendicitis
• Black Americans
• bowel movements
• colon health
• constipation
• diverticulitis
• Dr. Denis Burkitt
• Dr. Joel Kahn
• fiber
• gallstones
• hemorrhoids
• hiatal hernia
• mortality
• Plant-Based Diets
• standard American diet
• stool size
• varicose veins
• vegans
• vegetarians