Ancient Egypt was one of the great civilizations, lasting for 3,000 years, its knowledge of medicine vastly underestimated. They had medical subspecialties. The pharaohs, for example, had access to physicians dedicated to be guardians of the royal bowel movement, a title alternately translated from the hieroglyphics to mean Shepherd of the Anus. How’s that for a resumé builder?
Today, the primacy of its importance continues, with some calling for bowel habits to be considered a vital sign of how the body is functioning, along with blood pressure, and heart and breathing rates. Although we may not particularly like hearing the details of someone else’s bowel movement, it is a function that nurses and doctors need to assess.
Surprisingly, the colon remained relatively unexplored territory, one of the body’s final frontiers. For example, current concepts of what “normal” stools are like primarily emanate from the detailed records of 12 consecutive bowel movements in 27 healthy subjects from the United Kingdom, who boldly went where no one had gone before. Those must have been really detailed records.
The reason we need to define normal, when it comes to bowel movement frequency, for example, is how else can we define concepts like constipation or diarrhea if we don’t know what normal is. Standard physiology textbooks may not be helpful in this regard, implying that anything from one bowel movement every few weeks or months to 24 a day can be regarded as normal. Once every few months?
Of all human bodily functions defecation is perhaps the least understood and least studied. Can’t you just ask people? Turns out people tend to exaggerate. There’s a discrepancy between what people report and what researchers find when they actually have them recorded. It wasn’t until 2010 when we got the first serious look, defining normal stool frequency as between three per week and three per day, based on the fact that that’s where 98% of people tended to fall. But normal doesn’t necessarily mean optimal.
Having a “normal” salt intake can lead to a “normal” blood pressure, which can help us die from all the “normal” causes, like heart attacks and strokes. Having a “normal” cholesterol level in a society where it’s “normal” to drop dead of heart disease—our #1 killer, is not necessarily a good thing. And indeed, significant proportions of people with “normal” bowel function reported urgency, straining, and incomplete defecation, leading the researchers to conclude that that kind of thing must just be normal. Normal, maybe, if you’re eating a fiber-deficient diet. But not normal for our species. Defecation should not be a painful exercise. This is readily demonstrable. For example, the majority of rural Africans eating their traditional fiber-rich, plant-based diets can usually pass, without straining, a stool specimen on demand. See, the rectum may need to accumulate four or five ounces of fecal matter before the defecation reflex is fully initiated, and so if you don’t even build up that much over the day, you’d have to strain to prime the rectal pump.
Hippocrates thought bowel movements should ideally be two or three times a day, which is what you see in populations on traditional plant-based diets, on the kind of fiber intakes you see in our fellow great apes, and what may be more representative of the type of diets we evolved eating. It seems somewhat optimistic, though, to expect the average American to adopt a rural African diet. We can, however, eat more plant-based and bulk up enough to take the Hippocratic oath to go two to three times a day.
No need to obsess about it. In fact, there’s actually a “bowel obsession syndrome,” characterized in part by ideational rambling over bowel habits, but three times a day makes sense. We have what’s called a gastrocolic reflex, which consists of a prompt activation of muscular waves in our colon within 1 to 3 minutes of the ingestion of the first mouthfuls of food. Even just talking about food can cause your brain to increase colon activity. This suggests the body figured that one meal should be just about enough to fill you up down there. So, maybe we should eat enough unprocessed plant foods to get up to three a day, a movement for every meal.
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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