News Author: Laurie Barclay, MD
CME Author: Charles P. Vega, MD
CME Author: Charles P. Vega, MD
Clinical
Context
Most
patients in the United Kingdom do not receive the recommended daily allowance
for dietary fiber, and the authors of the current study describe how this might
contribute to rising rates of diverticular disease. High levels of consumption
of dietary fiber are associated with more rapid bowel transit times and
increased frequency of bowel movements. This leads to less water reabsorption
from the stools and softer, larger stools that are easier to pass. The overall
effect of these actions is less pressure on the colonic wall and, possibly,
less diverticular disease.
The
current study by Crowe and colleagues examines the effects of vegetarianism and
the amount of dietary fiber on the risk for diverticular disease.
Study
Synopsis and Perspective
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.
Study
Highlights
- Study data were
drawn from the EPIC-Oxford cohort. All participants were at least 20 years
old and resided in the United Kingdom.
- Participants
completed a questionnaire at baseline that estimated the intake of 130
different foods and beverages during the past year. Vegetarians were
defined as individuals who did not eat meat or fish. Participants who did
not consume meat, fish, eggs, or dairy products were considered vegans.
- The
questionnaire also inquired regarding demographic, health habit, and past
medical data.
- The main study
outcome was the relationship between vegetarianism, the amount of dietary
fiber, and the incidence of diverticular disease, which was ascertained
from hospital admission billing or death codes for diverticulosis,
diverticulitis, and diverticulum of the small or large intestine.
- 47,033 adults
provided study information, and 76% of participants were women. The mean
follow-up period was 11.6 years.
- 35% of men and
32% of women were vegetarians. Vegetarians were younger than
nonvegetarians, and nonvegetarians had higher body mass index values.
- Rates of
diabetes, hypertension, or hyperlipidemia were 2 to 3 times higher among
nonvegetarians vs vegetarians.
- There were 812
cases of diverticular disease during the follow-up period.
- Smoking was
associated with a higher risk for diverticular disease, including an 86%
increased risk for diverticular disease among heavy smokers vs nonsmokers.
- Higher body mass
index was also associated with a higher risk for diverticular disease, as
was hypertension, hyperlipidemia, and the use of female hormone therapy.
- The overall
rates of hospitalization or death from diverticular disease were 4.4%
among nonvegetarians and 3.0% among vegetarians and vegans.
- Compared with
nonvegetarians, vegetarians had a relative risk for 0.69 for the
development of diverticular disease (95% CI, 0.55 - 0.86). Vegans had an
even lower risk for diverticular disease vs nonvegetarians (relative risk,
0.28; 95% CI, 0.10 - 0.74).
- The duration of
vegetarianism had no significant effect on the risk for diverticular
disease.
- The quantity of
meat consumed among nonvegetarians also failed to affect the risk for
diverticular disease.
- In contrast,
there was a significant inverse association between the consumption of
dietary fiber and the risk for diverticular disease. Participants in the
highest fifth of dietary fiber consumption (at least 25.5 g/day among
women and 26.1 g/day among men) had a 41% lower risk for diverticular
disease (relative risk, 0.59; 95% CI, 0.46 - 0.78; P <
.001 trend) vs participants in the lowest fifth of dietary fiber
consumption (< 14 g/day).
- The main study
results were similar in subgroup analyses based on participants' sex and
age.
Clinical
Implications
- Rates of
diverticular disease have increased, as recommendations for intake of
dietary fiber are not met. High levels of consumption of dietary fiber are
associated with more rapid bowel transit times, less water reabsorption
from the stool, and increased frequency of bowel movements.
- The current
study suggests that vegetarianism and higher degrees of dietary fiber intake
are associated with a lower risk for diverticular disease.
From : medscape
regards, taniafdi ^_^
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