Optimal Bowel Movement Position

Compared to rural African populations eating traditional plant-based diets, white South Africans and black and white Americans have more than 50 times more heart disease, 10 times more colon cancer, more than 50 times more gallstones and appendicitis, and more than 25 times the rates of “pressure diseases”—diverticulitis, hemorrhoids, varicose veins, and hiatal hernia.

As I discussed in my Should You Sit, Squat, or Lean During a Bowel Movement?, bowel movements should be effortless. 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. Denis Burkitt, he blamed these conditions on the straining caused by a lack of fiber in the diet. He did, however, 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 at almost a 90-degree angle right at the end of the rectum that helps keep us from pooping our pants when we’re just out walking around. 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 defecation. (I remember sitting in geometry class wondering when I’d ever use the stuff I was learning. Little did I know I would one day be calculating anorectal angles with it! Stay in school, kids 🙂

How did they figure this out? Researchers filled latex tubes with a radiopaque fluid, stuck them up some volunteers, and took X-rays with the hips flexed at various angles. They concluded that flexing the knees towards the chest like one does when squatting may straighten that angle and reduce the amount of pressure needed to empty the rectum. This idea wasn’t directly put to the test until 2002, when researchers used defecography (which are X-rays taken while the person is defecating) on subjects in sitting and squatting positions. 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. 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 decrease the difficulty of defecating. They tried even higher footstools, but people complained of extreme discomfort using them. Nothing seemed to compare with actual squatting, which may give the maximum advantage. However, in developed nations, it may not be convenient. But, we can achieve a similar effect by leaning forward as we sit, with our hands on or near the floor. The researchers advise all sufferers from constipation to adopt this forward-leaning position when defecating, as the weight of our torso pressing against the thighs may put an extra squeeze on our colons.

Instead of finding ways to add 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, we 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 soft that you could pass them effortlessly at any angle?

Famed cardiologist Dr. Joel Kahn once said that you know you know you’re eating a plant-based diet when “you take longer to pee than to poop.”

In all seriousness, even squatting does not significantly decrease the pressure gradient that may cause a hiatal hernia. It does not prevent the 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 and reduction in blood flow to the heart and brain, resulting in defecation-related fainting and death. Just 15 seconds of straining can temporarily cut blood flow to the brain by 21% and blood flow to the heart by nearly one-half, thereby providing a mechanism for the well-known “bed pan death” syndrome. If you think you have to strain a lot while sitting, try having a bowel movement on your back. Bearing down for just a few seconds can send our 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 bed pans in hospitals. Hopefully, if we eat healthy enough, we won’t end up in the hospital to begin with.

Wondering How Many Bowel Movements Should You Have Every Day? Watch the video to find out!

The “forcing part of your stomach up through the diaphragm into our chest cavity” phenomenon is covered in my video Diet and Hiatal Hernia. The “ballooning of out-pouchings from our colon” is called diverticulosis. There’s a video I did about 6 years ago (Diverticulosis & Nuts), but I have some new and improved ones available: Diverticulosis: When Our Most Common Gut Disorder Hardly Existed and Does Fiber Really Prevent Diverticulosis?

 More on that extraordinary African data here:

So excited to be able to slip in a plug for Dr. Kahn’s work. His brand of “interpreventional cardiology” can be found at www.drjoelkahn.com.

In health,

Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:

Treating the Root Cause of Acid Reflux

In terms of preventing acid reflux heartburn, high-fat meals cause dramatically more acid exposure in the esophagus in the hours after a meal. I talked about this in Diet and GERD Acid Reflux Heartburn. High fiber intake decreases the risk, but why? One typically thinks of fiber as helping out much lower in the digestive tract.

A systematic review and meta-analysis published in 2013 found a highly significant protective association between esophageal adenocarcinoma and dietary fiber intake, suggesting that individuals with the highest fiber intakes have an approximately 30% lower risk of cancer. This could be because of the phytates in high-fiber foods slowing cancer growth, fiber’s anti-inflammatory effects, or even fiber-facilitated carcinogen removal. But those are all generic anti-cancer effects of whole plant foods. Specific to this type of acid irritation-induced esophageal cancer, fiber may reduce the risk of reflux in the first place. But how?

As you can see in my video, Diet and Hiatal Hernia, hiatus hernia occurs when part of the stomach is pushed up through the diaphragm into the chest cavity, which makes it easy for acid to reflux into the esophagus and throat. Hiatus hernia affects more than 1 in 5 American adults. In contrast, in rural African communities eating their traditional plant-based diets, the risk wasn’t 1 in 5; it was closer to 1 in 1,000—almost unheard of. Hiatus hernia is almost peculiar to those who consume western-type diets. Why are plant-based populations protected? Perhaps because they pass such large, soft stools, three or four times the volume as Westerners.

What does the size and consistency of one’s bowel movement have to do with hiatal hernia? A simple model may be helpful in illustrating the mechanism that produces upward herniation of the stomach through the hole (called the esophageal hiatus) in the diaphragm, which separates the abdomen from the chest. If a ball with a hole in its wall is filled with water and then squeezed, the water is pushed out through the hole. If we liken the abdominal cavity to the ball, the esophageal hiatus in the diaphragm corresponds with the hole in the ball. Abdominal straining during movement of firm feces corresponds to squeezing the ball and may result in the gradual expulsion of the upper end of the stomach from the abdominal cavity up into the chest. It’s like when we squeeze a stress ball. Straining at stool raises pressures inside our abdominal cavity more than almost any other factor.

In effect, straining at stool puts the squeeze on our abdomen and may herniate part of our stomach up. “Consistent with this concept is the observation that in Africans the lower esophageal sphincter is entirely subdiaphragmatic, whereas it usually straddles the diaphragm in Westerners and is above the diaphragm in the presence of hiatus hernia.”

This same abdominal pressure from straining may cause a number of other problems, too. Straining can cause herniations in the wall of the colon itself, known as diverticulosis. That same pressure can backup blood flow in the veins around the anus, causing hemorrhoids, and also push blood flow back into the legs, resulting in varicose veins.

Hiatal hernia is not the only condition that high-fiber diets may protect against. See:

I also have a load of other bowel movement videos:

In health,

Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations: