HIGH FIBRE DIETS AND DIVERTICULOSIS

Colonic diverticulosis is very common in developed countries. Diverticula of the large bowel are out-pouchings in the wall of the colon. These occur at weak points in the circular muscle where blood vessels penetrate to supply the mucosa or lining of the bowel.


Diverticulosis affects about one third of adults over aged 60 in the US.  Most cases are picked up on colonoscopies in people who have no symptoms. Diverticular disease is the term used when people have diverticulosis with a complication. It is estimated that between 10 and 25% of people with diverticulosis will develop diverticulitis at some stage.


Complications can be severe, and include  infection, bleeding, abscesses, intestinal perforations, inflammation of the bowel (colitis /diverticulitis) and in the worst cases, people can die from these. Symptoms include abdominal cramping, pain (usually in the lower left belly), fever, nausea and vomiting, and altered bowel habits.


In a classic example of a misleading study - a group of researchers out of North Carolina stated that they found no association between dietary fibre and diverticulosis. They looked at two groups of people - one group was supposedly the “high fibre” group  eating  25g of dietary fibre a day, and the “low fibre” group ate only 8g a day. Researchers found no difference in the rates of diverticulosis between the two groups and thus concluded that a low fibre diet was not associated with diverticulosis. The university press release was entitled “Diets high in fibre won’t protect against diverticulosis”. The media quickly picked up on this and ran articles with headlines trumpeting this “important finding”.


In order to understand why this is such a misleading conclusion, let’s look at the facts about fibre consumption. People used to consume more than 100g of fibre a day. The minimum recommended daily amount of fibre is set low at 32g. So we can see that in this flawed study, the so-called high fibre group was still actually eating a very low fibre diet. Really the researchers were comparing extremely low fibre intake with just very low intake.


Another popular misconception that is still around, is that eating seeds and nuts should be avoided in people with diverticular disease. People were also told in the past to avoid foods such as cucumber, strawberries and tomatoes for fear that their tiny seeds would lodge in the little pockets in the intestine and causes future problems. This myth has now been debunked.


In African populations that have almost no diverticulosis, people are eating diets consisting mostly of large plates of leafy vegetables. They eat plant based diets containing between 70 and 90 g of fibre a day, more than most North American vegetarian diets! A  better study of 47 000 people showed conclusively that consuming a vegetarian diet and having a high fibre intake were associated both with having a lower risk of admission to hospital and death from diverticular disease.


Compared with people who eat as little as one serve of meat a day, vegetarians have a 35% lower risk of developing diverticulosis. People who eat a strictly plant based diet had close to 80% lower risk of developing the disease. Just another reason to eat a high fibre whole-food plant-based diet.