Diverticula are out-pouchings of our intestine. Doctors like using a tire analogy: high pressures within the gut can force the intestines to balloon out through weak spots in the intestinal wall like an inner tube poking out through a worn tire tread. You can see what they actually look like in my video, Diverticulosis: When Our Most Common Gut Disorder Hardly Existed. These pockets can become inflamed and infected, and, to carry the tire analogy further, can blow out and spill fecal matter into the abdomen, and lead to death. Symptoms can range from no symptoms at all, to a little cramping and bloating, to “incapacitating pain that is a medical emergency.” Nine out of ten people who die from the disease never even knew they had it.
The good news is there may be a way to prevent the disease. Diverticular disease is the most common intestinal disorder, affecting up to 70% of people by age 60. If it’s that common, though, is it just an inevitable consequence of aging? No, it’s a new disease. In 1907, 25 cases had been reported in the medical literature. Not cases in 25% of people, but 25 cases period. And diverticular disease is kind of hard to miss on autopsy. A hundred years ago, in 1916, it didn’t even merit mention in medical and surgical textbooks. The mystery wasn’t solved until 1971.
How did a disease that was almost unknown become the most common affliction of the colon in the Western world within one lifespan? Surgeons Painter and Burkitt suggested diverticulosis was a deficiency disease—i.e., a disease caused by a deficiency of fiber. In the late 1800s, roller milling was introduced, further removing fiber from grain, and we started to fill up on other fiber-deficient foods like meat and sugar. A few decades of this and diverticulosis was rampant.
This is what Painter and Burkitt thought was going on: just as it would be easy to squeeze a lump of butter through a bicycle tube, it’s easy to move large, soft, and moist intestinal contents through the gut. In contrast, try squeezing through a lump of tar. When we eat fiber-deficient diets, our feces can become small and firm, and our intestines have to really squeeze down hard to move them along. This buildup of pressure may force out those bulges. Eventually, a low-fiber diet can sometimes lead to the colon literally rupturing itself.
If this theory is true, then populations eating high-fiber diets would have low rates of diverticulosis. That’s exactly what’s been found. More than 50% of African Americans in their 50s were found to have diverticulosis, compared to less than 1% in African Africans eating traditional plant-based diets. By less than 1%, we’re talking zero out of a series of 2,000 autopsies in South Africa and two out of 4,000 in Uganda. That’s about one thousand times lower prevalence.