Vegetarian Diet May Lower Risk for Diverticular Disease

Laurie Barclay, MD

July 20, 2011

July 20, 2011 — Following a vegetarian diet and having a high intake of dietary fiber are associated with a lower risk for diverticular disease, according to the results of a prospective cohort study reported online July 19 in the BMJ.

"Diverticular disease has been termed a 'disease of western civilisation' because of its high prevalence in countries like the United Kingdom and United States compared with certain parts of Africa," write Francesca L. Crowe, nutritional epidemiologist at the Cancer Epidemiology Unit, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom, and colleagues. "We examined the associations of vegetarianism and the intake of dietary fibre (defined as non-starch polysaccharides) with the risk of diverticular disease using information from hospital admission data and death certificates for England and Scotland in men and women taking part in the European Prospective Investigation into Cancer and Nutrition (EPIC)-Oxford cohort."

The study cohort consisted of 47,033 men and women living in England or Scotland and enrolled in EPIC-Oxford, a cohort of predominantly health-conscious participants recruited throughout the United Kingdom. Of these, 15,459 (33%) reported consuming a vegetarian diet at baseline. A 130-item, validated food frequency questionnaire was used to estimate dietary fiber intake.

Linkage with hospital records and death certificates allowed identification of cases of diverticular disease. Multivariate Cox proportional hazards regression models allowed estimation of hazard ratios (HRs) and 95% confidence intervals (CIs) for the risk for diverticular disease by diet group and quintiles of dietary fiber intake.

Of 812 cases of diverticular disease identified during follow-up (mean duration, 11.6 years), 806 were hospital admissions and 6 were deaths. Compared with meat eaters, vegetarians had a 31% lower risk for diverticular disease, after adjustment for confounding variables including smoking, alcohol use, and body mass index (relative risk, 0.69; 95% CI, 0.55 - 0.86). Meat eaters between the ages of 50 and 70 years had a 4.4% cumulative probability of hospitalization or death from diverticular disease vs 3.0% for vegetarians.

The risk for diverticular disease was also inversely associated with dietary fiber intake. Compared with participants in the lowest quintile of dietary fiber intake (< 14 g/day for both women and men), those in the highest quintile (≥ 25.5 g/day for women and ≥ 26.1 g/day for men) had a 41% lower risk for diverticular disease (HR, 0.59; 95% CI, 0.46 - 0.78; P < .001 trend).

Vegetarian diet and higher fiber intake were each significantly associated with a lower risk for diverticular disease, after mutual adjustment.

"Consuming a vegetarian diet and a high intake of dietary fibre were both associated with a lower risk of admission to hospital or death from diverticular disease," the study authors write.

Limitations of this study include unmeasured confounding, possible lack of generalizability, the possibility that vegetarians would undergo fewer tests and/or that meat eaters would have more gastrointestinal tract symptoms resulting in a diagnosis of diverticular disease, and undetermined validity of a diagnosis of diverticular disease from hospital records.

In an accompanying editorial, David J. Humes and Joe West, from Nottingham University Hospital, in Nottingham, United Kingdom, note that the findings must be interpreted in the light of these limitations.

"At a population level, if the available absolute risks are converted into a number needed to treat, about 71 meat eaters would have to become vegetarians to prevent one diagnosis of diverticular disease as measured in this study," Drs. Humes and West write. "...Overall the opportunity for preventing the occurrence of diverticular disease and other conditions, such as colorectal cancer, probably lies in the modification of diet, at either a population or an individual level. However, far more evidence is needed before dietary recommendations can be made to the general public."

Cancer Research UK funded the EPIC study. One of the study authors reports being a member of the Vegan Society. Drs. Humes and West have disclosed no relevant financial relationships.

BMJ. 2011;343:d4115, d4131.


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