Transcript: Diet and Hiatal Hernia
In terms of preventing acid reflux heartburn, I’ve talked about how high-fat meals cause dramatically more acid exposure in the esophagus in the hours after a meal, but why does high fiber intake decrease the risk? One typically thinks of fiber helping out much lower in the digestive tract.
A systematic review and meta-analysis 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, or could be the anti-inflammatory effects, or fiber could be removing carcinogens. But those are all generic anti-cancer effects of whole plant foods. Specific to this type of acid irritation-induced esophageal cancer, fiber may decrease the risk of reflux in the first place. But how?
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 up into the esophagus and throat. It affects more than 1 in 5 American adults. In contrast, in rural African communities who were eating their traditional plant-based diets, it wasn't 1 in 5; it was closer to one in a thousand—almost unheard of. It’s 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 of Westerners.
What does the size and consistency of one’s bowel movement have to do with hiatal hernia? A simple model may help illustrate the mechanism producing upward herniation of the stomach through the hole in the diaphragm, which separates the abdomen from the chest, called the esophageal hiatus. If a ball with a hole in its wall is filled with water and then squeezed, the water is expressed through the hole. The abdominal cavity may be likened to a ball, the hole in the ball corresponding to the esophageal hiatus in the diaphragm. So abdominal straining during efforts to evacuate firm feces corresponds to squeezing the ball, and may result in gradual expulsion of the upper end of the stomach from the abdominal cavity up into the chest. It’s like when you squeeze one of those stress balls. Straining at stool raises pressures inside our abdominal cavity more than almost any other factor.
When we bear down and strain at stool, it’s like squeezing 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 sub-diaphragmatic, whereas it usually straddles the diaphragm in Westerners, and is above the diaphragm in the presence of hiatus hernia.
And the same abdominal pressure from straining that may cause hiatal hernias may cause a number of other problems. The straining can cause herniations in the wall of the colon itself, known as diverticulosis. And that same pressure can also back up blood flow into the veins around the anus, causing hemorrhoids, and push blood flow back into the legs, resulting in varicose veins as well.
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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