Inflammatory bowel disease, or IBD for short,
affects an estimated 3 million adults in the US and another 1.3 million in
Europe. And diagnoses have been increasing, particularly in newly
industrialised countries.
Previously published research has linked IBD
risk with several lifestyle factors, but it’s not clear if adopting and
maintaining a healthy lifestyle might lower the risk of developing the
condition in the first place.
A large international study, published online
in the journal Gut has recently found that adopting and maintaining a healthy
lifestyle might prevent up to 60% of inflammatory bowel disease cases—Crohn’s
disease and ulcerative colitis.
The findings prompt the study authors to
suggest that, subject to further research, particularly in those at high risk
of developing these conditions, lifestyle changes may be a feasible option for
future preventive strategies.
To find out, they drew on participant data
from the Nurses’ Health Study (NHS), NHSII, and the Health Professionals
Follow-up Study (HPFS).
The Nurses Health Study enrolled 121,700
female nurses (aged 30–55) from 11 US states in 1976, while the NHSII study,
established in1989, monitored 116,429 female nurses (aged 25–42) from 15 US
states. The HPFS included 51,529 male doctors (40–75) from across the US in
1986.
The researchers created modifiable risk scores
(MRS) for each participant based on established modifiable risk factors for IBD
to estimate the proportion of IBD cases that could have been avoided.The MRS
ranged from 0-6, with higher scores denoting more risk factors.
These risk factors included weight (BMI);
smoking; use of non-steroidal anti-inflammatory drugs; physical activity; and
daily intake of fruit, fibre, vegetables, polyunsaturated fatty acids (PUFAs)
and red meat.
The researchers then estimated the proportion
of avoidable cases if an overall healthy lifestyle were adopted and maintained.
Scores of 0-9 were assigned to each participant, with higher scores indicating
a healthier lifestyle.
A healthy lifestyle comprised: BMI between
18.5 and 25; never smoking; at least 7.5 weekly MET hours (METS express the
amount of energy (calories) expended per minute of physical activity); at least
8 daily servings of fruit and veg; less than half a daily serving of red meat;
at least 25 g of fibre/day; at least 2 weekly servings of fish; at least half a
daily serving of nuts/seeds; and a maximum of 1 alcoholic drink/day for women
or 2 for men.
During the monitoring period (NHS, HPFS:
1986–2016; NHSII: 1991–2017), 346 cases of Crohn’s disease and 456 cases of
ulcerative colitis were reported.
Based on the MRS scores, the researchers
estimated that a low MRS could have prevented 43% and 44.5%, respectively, of
Crohn’s disease and ulcerative colitis cases.
Similarly, maintaining a healthy lifestyle
could have prevented 61% of Crohn’s disease cases and 42% of ulcerative colitis
cases.
The researchers applied the scoring systems to
data from three large European studies to validate their findings: the Swedish
Mammography Cohort (37,275 participants); the Cohort of Swedish Men (40,810);
and the European Prospective Investigation into Cancer and Nutrition (404,144).
These calculations showed that a low MRS and
maintaining a healthy lifestyle could have, respectively, prevented 44%–51% and
49%–60.5% of Crohn’s disease cases, and 21%–28% and 47%–56.5% of ulcerative
colitis cases.
This is an observational study, and as such
can’t establish cause. And the researchers acknowledge that the average age at
which IBD was diagnosed was older than is typical. Nor were early lifestyle
factors considered that may have been influential. These included antibiotic
prescriptions; breastfeeding; environmental factors such as pollution; stress;
and socioeconomic factors.
“A key assumption of our findings is that the
relationship between lifestyle factors and IBD development is causal. Though
this has yet to be established, several lines of evidence support the critical
role of environmental and lifestyle factors in the development of IBD,” they
write.
“Lifestyle modification may be an attractive
target for future prevention strategies in IBD,” they add. “This may be of
particular relevance to high-risk groups, such as first-degree relatives of IBD
patients, who have an estimated 2%–17% risk of developing the disease over
their lifetime.”
Ref:
Lifestyle factors for the prevention of
inflammatory bowel disease doi:10.1136/gutjnl-2022-328174