— Modifying diet, not smoking, exercising could help, analysis of cohort studies suggests
Zaina Hamza, Staff Writer, MedPage Today
December 6, 2022
Adopting and maintaining a healthy lifestyle may prevent inflammatory bowel disease (IBD), according to findings from an analysis of three prospective U.S. cohort studies, which were validated in three external European cohorts.
In the primary analysis, maintaining low modifiable risk scores — based on risk factors including body mass index, smoking status, use of non-steroidal anti-inflammatory drugs, physical activity, and daily consumption of fruit, vegetables, fiber, polyunsaturated fatty acids, and red meat — could have prevented 42.9% of Crohn’s disease cases and 44.4% of ulcerative colitis cases, reported Hamed Khalili, MD, MPH, of Massachusetts General Hospital in Boston, and colleagues.
Moreover, adherence to a healthy lifestyle could have prevented 61.1% of Crohn’s disease cases and 42.2% of ulcerative colitis cases, they noted in Gut.
“We were surprised by the proportion of cases that could have been prevented through lifestyle modifications,” Khalili told MedPage Today. “One reason for this finding may be that our population was older and therefore most of our cases of IBD happened in older adults.”
“We know that lifestyle and environmental factors play a bigger role in the development of IBD in this population as compared to those who are diagnosed with disease earlier in life,” he added.
These findings from the Nurses’ Health Study (NHS), the NHS II, and the Health Professionals Follow-Up Study (HPFS) were largely validated in three external European cohorts — the Swedish Mammography Cohort, Cohort of Swedish Men, and the European Prospective Investigation into Cancer and Nutrition.
Looking at cases of Crohn’s disease among the European validation cohorts, adhering to low-risk factors could have prevented 44% to 51% of cases, while adhering to a healthy lifestyle could have prevented 49% to 60% cases. For ulcerative colitis, adherence to low-risk factors could have prevented 21% to 28% of cases, while healthy lifestyle adherence could have prevented 47% to 56% of cases.
For every 1-point increase in modifiable risk score, a higher risk of Crohn’s disease (P for trend<0.0001) and ulcerative colitis (P for trend=0.008) was observed, and was similar for men and women.
IBD affects about 3.1 million people in the U.S. and 1.3 million in Europe, with incidence rising globally, especially among newly industrialized countries, Khalili’s group said. IBD is associated with an annual healthcare cost of $23,000 per patient in the U.S., and there are no current strategies to prevent the development of IBD. While one approach to preventing many chronic diseases is modification of lifestyle and dietary factors, the success of adhering to such changes remains unclear.
For this study, Khalili and colleagues examined data on 72,290 participants from the NHS, 93,909 from the NHS II, and 41,871 from the HPFS. The NHS enrolled female nurses ages 30 to 55 across 11 states in 1976. NHS II assessed a slightly younger cohort of female nurses (ages 25 to 42) from 15 states starting in 1989, while the HPFS enrolled male physicians ages 40 to 75 across all states in 1986.
In order to externally validate their findings, the researchers assessed data on 40,810 participants in the Cohort of Swedish Men, 404,144 from the European Prospective Investigation into Cancer and Nutrition, and 37,275 from the Swedish Mammography Cohort.
Using participant baseline and biennial questionnaires that assessed lifestyle factors, anthropomorphic data, and medical history, Khalili and colleagues developed modifiable risk scores ranging from 0 to 6 for Crohn’s disease and ulcerative colitis, with higher scores indicating more risk factors. Healthy lifestyle scores ranging from 0 to 9 were also developed, based on recommendations from the American Heart Association and other organizations, with higher scores indicating a healthier lifestyle.
A healthy lifestyle included never smoking, a BMI between 18.5 and 25, and engaging in physical activity of at least 7.5 metabolic equivalent of task-hours per week, in addition to consuming less than half a serving of red meat per day, at least eight daily servings of fruit/vegetables, at least half a serving of nuts or seeds per day, at least two servings of fish per week, at least 25 g of daily fiber, and a maximum of one daily alcoholic beverage for women and two for men.
Across 5,117,021 person-years of follow-up, 346 cases of Crohn’s disease and 456 cases of ulcerative colitis were reported.
On falsification analysis, adherence to low-risk factors for Crohn’s disease could have also prevented 32.3% of cases of rheumatoid arthritis, 13.3% of cases of colorectal cancer, and 14% of cases of cardiovascular disease, though this was not the case for ulcerative colitis.
“This is largely due to differences in strength of associations and prevalence of risk factors, and presence of other modifiable risk factors such as alcohol and medications or supplements which are strongly associated with these other conditions,” Khalili and colleagues suggested.
They acknowledged that younger-onset IBD was under-represented in their study, since the mean age of the cohort (about 45) was higher than the usual age at onset of IBD. In addition, data on other modifiable risk factors such as stress were not explored, and high-risk individuals were not assessed.
Zaina Hamza is a staff writer for MedPage Today, covering Gastroenterology and Infectious disease. She is based in Chicago.
This study was primarily supported by the National Institutes of Health.
Khalili reported support from the American College of Gastroenterology Senior Research Award and the Beker Foundation, as well as consulting fees from AbbVie and Takeda, and grant funding from Pfizer and Takeda.
Co-authors also reported multiple relationships with industry.