Have you recently been told by your General Practitioner (CP) or gastroenterologist that you have “diverticulosis” and wonder how you should be eating differently to keep it from getting worse?
What is “diverticulosis”?
Diverticulosis is where your colon (large intestine) has small “pockets” in it called diverticula which can cause a number of symptoms or in some people, no symptoms at all.
Diverticula can vary in number from one to literally hundreds. Generally, diverticula increase in number and size over time and range in size from 0.5-1 cm (0.2-0.4 inch) in diameter to 2 cm (0.8 inch). Diverticulosis occurs in about 5% of adults younger than forty years old, but rise to at least 50% of those older than sixty, with 65% of those who older than 85 having diverticulosis.
These little pouches were once thought to be cause by a diet that was too low in fiber which caused the stools to move too slowly though the colon, resulting in constipation. Based on this “fiber hypothesis”, the remedy was thought to be to eat a diet high in fiber; including whole grain bread, unprocessed wheat bran, porridge and fruit. For the last 50 years or so, increased fiber intake has been the recommendation for treatment of diverticulosis, including by the GI Society of Canada and the American Gastrolenterology Association recommends at least 25 g of fiber per day[2,3]. It was thought that increased fiber would increase the volume of the stool and thus require less straining to move the bowels and prevent weakening of the bowel wall, reducing the occurrence of these “pouches”. Unfortunately, several recent studies have shed doubt on the “fiber hypothesis” [4-8].
Not only did a 2012 study find no association between a low fiber diet and diverticulosis , the study found that increasing total fiber intake in the form of grains, insoluble fiber and soluble fiber actually increased the prevalence of diverticulosis!
“People with the lowest fiber intake were 30% less likely to develop diverticula than people whose diets included the most fiber.” 
Subsequent studies have either found no association between the amount of fiber intake and diverticulosis  or that there was no association between diverticulosis and constipation symptoms .
These findings left researchers and clinicians with little evidence for continuing to recommend a high fiber diet in diverticulosis, but no alternative options.
ADDENDUM (July 17 2019): There are a number of hypotheses as to what causes diverticulosis with many thinking it could be related to colonic aging weakening of the smooth muscle bands, motor dysfunction, increased luminal pressure, as well of lack of dietary fiber.
Eating foods with soluble and insoluble fiber and drinking sufficient fluid is good, however the source of that fiber is now thought to be important, as I will outline below.
Logical Hypothesis for Diverticulosis
A recent hypothesis is that the increased pressure in the colon that resulted from the intake of so much fiber; particularly the types of fiber that are easily fermented by gut bacteria is what weakens the colon wall, resulting in these ‘pockets’ or diverticula.
What seemed to add credibility to this hypothesis is that historically (prior to WWII) diverticula were seen in a specific region of the colon (proximal colon) in people in Asian countries, with the condition only affecting the right side. This has been explained by the high prevalence of lactose intolerance (inability to digest the sugar in milk and dairy) which exists in Asians. As well, the incidence of this right-sided diverticulosis has been lowest in European populations, where lactose intolerance is very low . Similarly, in Western countries, most of the diverticula are on the left side of the colon, which is thought to be associated with the higher ingestion of wheat, compared historically to Asian countries .
Both lactose and the fructans in wheat are carbohydrates that are easily fermented by gut microbes and which results in high amounts of water being drawn into the colon, resulting in increasing pressure on the colon wall from the gas produced by the microbes, possibly leading to the creation of these diverticula.
Of interest, consumption of wheat in Japan and in South Korea has increased considerably since WWII and there is now a considerably higher incidence of left colon diverticula now being observed there, as well .
Use of a low-FODMAP Diet in diverticulosis
FODMAPS is an acronym for fermentable oligosaccharides, disaccharides, monosaccharides and polyols (sugar alcohols) which are the specific types of carbohydrate that are fermented by the gut bacteria, resulting in increased gas production, abdominal pain, bloating and either diarrhea and constipation or a combination of both. These are very similar symptoms as are observed in Irritable Bowel (IBS) Syndrome and a low-FODMAP diet has long been used to minimize the symptoms in IBS, and is now being used to reduce the same symptoms in diverticulosis.
It is thought that use of a low-FODMAP diet in those with diverticulosis may reduce the occurrence of diverticulitis; which is painful inflammation of these diverticula that often requires medical treatment ranging from antibiotics and pain medication, to bowel resection as is common in Inflammatory Bowel Disease (IBD), such as Ulcerative Colitis and Crohn’s disease.
I offer a Diverticulosis Option for those who want to have specific nutrition education to help them reduce their symptoms and lower the likelihood of their disease progressing to diverticulitis.
Even if you are already following a low-carbohydrate diet and not eating wheat, foods with lactose or fruit, it’s important to know that there are a number of low carbohydrate vegetables that also contain some of these fermentable carbohydrates, as do many of the sugar alcohols many people following a low carb diets use. Reducing the intake of these specific vegetables and sticking to sweeteners that are low FODMAP can greatly help!
If you would like a Meal Plan designed just for you in light of your diagnosis, as well as specific nutrition education services on how to minimize the symptoms of diverticulosis and lower the likelihood of it progressing to diverticulitis, please click on the Diverticulosis Option, under the Services tab to learn more.
If you have questions, please feel free to send me a note using the Contact Me form above and I will reply as soon as I can.
To your good health!
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- GI Society, Canadian Society of Intestinal research, https://badgut.org/information-centre/a-z-digestive-topics/diverticular-disease/
- Painter NS, Diverticulosis of the Colon and Diet. Br Med J. 1969 Jun 21;2(5659):764-5.
- American Gastroenterological Association. A Patient Guide: Managing Diverticulitis. Gastroenterology. 2015;149:1977–1978
- Tan KY, Seow-Choen F. Fiber and colorectal diseases: separating fact from fiction. World J Gastroenterol. 2007;13:4161–4167.
- Unlu C, Daniels L, Vrouenraets BC, Boermeester MA. A systematic review of high-fibre dietary therapy in diverticular disease. Int J Colorectal Dis. 2012;27:419–427.
- Peery AF, Sandler RS. Diverticular disease: reconsidering conventional wisdom. Clin Gastroenterol Hepatol. 2013;11:1532–1537.
- Tursi A, Papa A, Danese S. Review article: the pathophysiology and medical management of diverticulosis and diverticular disease of the colon. Aliment Pharmacol Ther. 2015;42:664–684.
- Elisei W, Tursi A. Recent advances in the treatment of colonic diverticular disease and prevention of acute diverticulitis. Ann Gastroenterol. 2016;29:24–32.
- Peery AF, Barrett PR, Park D, Rogers AJ, Galanko JA, Martin CF, Sandler RS. A high-fiber diet does not protect against asymptomatic diverticulosis. Gastroenterology. 2012;142:266–272
- Peery AF, Sandler RS, Ahnen DJ, Galanko JA, Holm AN, Shaukat A, Mott LA, Barry EL, Fried DA, Baron JA. Constipation and a low-fiber diet are not associated with diverticulosis. Clin Gastroenterol Hepatol. 2013;11:1622–1627
- Braunschmid T, Stift A, Mittlböck M, Lord A, Weiser FA, Riss S. Constipation is not associated with diverticular disease – Analysis of 976 patients. Int J Surg. 2015;19:42–45.
- Uno Y, van Velkinburgh JC. Logical hypothesis: Low FODMAP diet to prevent diverticulitis. World J Gastrointest Pharmacol Ther. 2016;7(4):503–512. doi:10.4292/wjgpt.v7.i4.503