Diverticular Disease
The hypothesis that diverticulosis is a deficiency disease of Western civilization was made popular by Painter and Burkitt based on their observation that diverticulosis was rare in rural Africa, but increasingly common in economically developed countries. They attributed the difference in disease prevalence to differences in dietary fiber. They presumed that the rural African diet was high in dietary fiber and that economically developed countries consumed a low-fiber diet. They proposed that this deficiency of fiber predisposed the population to diverticulosis. Neither diet nor diverticulosis was actually measured in their studies and they did not account for important potentially confounding variables such as age and sex.
Painter proposed that the deficiency of fiber led to constipation and high-pressure segmentation of the colon that resulted in mucosal herniation through weak sections of the colon wall. To support their hypothesis they conducted motility studies that compared intracolonic pressures in patients with diverticulosis with intracolonic pressures in controls. Although they reported that patients with diverticulosis had higher colonic pressures, the investigators only reported pressure measurements for select cases and there were no statistical analyses. Motility studies of the colon have not consistently shown that patients with diverticulosis have increased colonic pressures. Along the same lines, Burkitt et al conducted colonic transit studies and found that a population consuming a Western diet had longer mean colonic transit times and lower mean stool weights compared with an African population. Studies in populations with colonic diverticula, on the other hand, have shown shorter colonic transit times compared with controls.
The fiber hypothesis is extremely popular. The concept of forceful contractions of the colon leading to herniation makes sense. However, the hypothesis has persisted for 4 decades largely without proof. Historically it has been a challenge to refute the hypothesis because a proper study would require a structural examination (eg, barium enema) in asymptomatic individuals to document the presence of diverticula. With the widespread use of screening colonoscopy we now have the opportunity to study large numbers of people who are undergoing a structural examination of their colon in the absence of symptoms.
We recently published a colonoscopy-based, cross-sectional study of dietary risk factors for diverticulosis. Each of the 2104 subjects had a colonoscopy to the cecum between 1998 and 2010. Participants completed a telephone interview that included a comprehensive semiquantitative food frequency questionnaire as well as questions about bowel frequency and physical activity. Contrary to expectation, we found that a high-fiber diet was associated with a higher (not lower) prevalence of diverticula. The association with dietary fiber intake was dose-dependent and stronger when limited to cases with multiple diverticula. We also found that constipation was not a risk factor for diverticulosis. Instead, we found that participants who had regular bowel movements (7 bowel movements/wk) had a 34% higher risk of diverticulosis compared with participants who had less frequent bowel movements (<7 bowel movements/wk).
Study participants were interviewed after their colonoscopy and were aware, in most cases, that diverticulosis had been found. In response to the concern that the study may have been susceptible to response bias and reverse causality from the subjects' knowledge of their diagnoses, we performed a second cross-sectional study in a different population in which we limited the analysis to participants with no knowledge of their diverticulosis status. The second study confirmed the results of the initial work (unpublished data). Similar results with respect to fiber were found in 2 colonoscopy-based studies in non-Western populations, although diverticula in Asia are found predominantly in the right colon and may have a different etiology.
Although recent studies have suggested that a high-fiber diet does not protect against the development of diverticulosis there is some evidence that a high-fiber diet may protect against diverticular disease. Crowe et al studied 47,033 men and women in England and Scotland. Individuals who reported consuming a vegetarian diet had a lower risk of admission to the hospital or death from diverticular disease. There was also an inverse association for fiber intake. Those in the highest quintile of fiber consumption were 41% less likely to have a complication from diverticular disease. Similar results were seen in a prospective study of US male health professionals.
It is important to recognize that the research to date was designed to improve our understanding of risk factors for diverticulosis and its complications and not to make dietary recommendations. There are advantages to eating a high-fiber, plant-based diet with respect to constipation, heart disease, and cancer.
Fiber
The hypothesis that diverticulosis is a deficiency disease of Western civilization was made popular by Painter and Burkitt based on their observation that diverticulosis was rare in rural Africa, but increasingly common in economically developed countries. They attributed the difference in disease prevalence to differences in dietary fiber. They presumed that the rural African diet was high in dietary fiber and that economically developed countries consumed a low-fiber diet. They proposed that this deficiency of fiber predisposed the population to diverticulosis. Neither diet nor diverticulosis was actually measured in their studies and they did not account for important potentially confounding variables such as age and sex.
Painter proposed that the deficiency of fiber led to constipation and high-pressure segmentation of the colon that resulted in mucosal herniation through weak sections of the colon wall. To support their hypothesis they conducted motility studies that compared intracolonic pressures in patients with diverticulosis with intracolonic pressures in controls. Although they reported that patients with diverticulosis had higher colonic pressures, the investigators only reported pressure measurements for select cases and there were no statistical analyses. Motility studies of the colon have not consistently shown that patients with diverticulosis have increased colonic pressures. Along the same lines, Burkitt et al conducted colonic transit studies and found that a population consuming a Western diet had longer mean colonic transit times and lower mean stool weights compared with an African population. Studies in populations with colonic diverticula, on the other hand, have shown shorter colonic transit times compared with controls.
The fiber hypothesis is extremely popular. The concept of forceful contractions of the colon leading to herniation makes sense. However, the hypothesis has persisted for 4 decades largely without proof. Historically it has been a challenge to refute the hypothesis because a proper study would require a structural examination (eg, barium enema) in asymptomatic individuals to document the presence of diverticula. With the widespread use of screening colonoscopy we now have the opportunity to study large numbers of people who are undergoing a structural examination of their colon in the absence of symptoms.
We recently published a colonoscopy-based, cross-sectional study of dietary risk factors for diverticulosis. Each of the 2104 subjects had a colonoscopy to the cecum between 1998 and 2010. Participants completed a telephone interview that included a comprehensive semiquantitative food frequency questionnaire as well as questions about bowel frequency and physical activity. Contrary to expectation, we found that a high-fiber diet was associated with a higher (not lower) prevalence of diverticula. The association with dietary fiber intake was dose-dependent and stronger when limited to cases with multiple diverticula. We also found that constipation was not a risk factor for diverticulosis. Instead, we found that participants who had regular bowel movements (7 bowel movements/wk) had a 34% higher risk of diverticulosis compared with participants who had less frequent bowel movements (<7 bowel movements/wk).
Study participants were interviewed after their colonoscopy and were aware, in most cases, that diverticulosis had been found. In response to the concern that the study may have been susceptible to response bias and reverse causality from the subjects' knowledge of their diagnoses, we performed a second cross-sectional study in a different population in which we limited the analysis to participants with no knowledge of their diverticulosis status. The second study confirmed the results of the initial work (unpublished data). Similar results with respect to fiber were found in 2 colonoscopy-based studies in non-Western populations, although diverticula in Asia are found predominantly in the right colon and may have a different etiology.
Although recent studies have suggested that a high-fiber diet does not protect against the development of diverticulosis there is some evidence that a high-fiber diet may protect against diverticular disease. Crowe et al studied 47,033 men and women in England and Scotland. Individuals who reported consuming a vegetarian diet had a lower risk of admission to the hospital or death from diverticular disease. There was also an inverse association for fiber intake. Those in the highest quintile of fiber consumption were 41% less likely to have a complication from diverticular disease. Similar results were seen in a prospective study of US male health professionals.
It is important to recognize that the research to date was designed to improve our understanding of risk factors for diverticulosis and its complications and not to make dietary recommendations. There are advantages to eating a high-fiber, plant-based diet with respect to constipation, heart disease, and cancer.
SHARE
