Environmental and Dietary Differences of Inflammatory Bowel Disease in Eastern and Western Populations

Min Zhao; Rui Feng; Shomron Ben-Horin; Xiaojun Zhuang; Zhenyi Tian; Xiaozhi Li; Ruiqi Ma; Ren Mao; Yun Qiu; Minhu Chen

Aliment Pharmacol Ther. 2022;55(3):266-276.

Abstract and Introduction

Abstract

Background: While the incidence of inflammatory bowel disease (IBD) has stabilised in the West, it is still increasing in several newly industrialised countries.

Aims: To investigate whether the environmental and dietary risk factors for IBD differ between Eastern and Western populations

Methods: We systematically searched PubMed, Embase, and Web of Science for studies published from inception through June 30, 2020. Data were pooled using a random effects model.

Results: Overall, 255 studies were assessed. We identified 25 risk factors for IBD, seven of which were noted in both Eastern and Western populations: family history of Crohn's disease [CD] or ulcerative colitis [UC], former smoking (CD/UC), smoking (CD), appendicectomy (CD), tonsillectomy (CD), meat and meat products (CD), and vitamin D deficiency (UC). The remaining factors, including urban living, current smoking, antibiotics, oral contraceptives, caesarean section, isotretinoin, total energy, fat, cholesterol, fatty acids and their sub-classifications, eggs, and soft drinks, were associated with an increased risk of IBD in Western or Eastern populations only. We identified 21 protective factors for IBD, among which eight were common in the East and West: farm animals (CD/UC), Helicobacter pyloriinfection (CD/UC), multiple births (CD), physical activity (CD), history of breastfeeding (CD), pets (UC), current smoking (UC), and coffee intake (UC).

Abstract and Introduction
Methods
Results
Discussion
Conclusion
References

Table 1. Summary of environmental factors for Crohn's disease (CD) and ulcerative colitis (UC)
Environmental factors	CD		UC		Environmental factors	CD		UC
Environmental factors	East	West	East	West	Environmental factors	East	West	East	West
1. Appendectomy	↑	↑	→	↓	14. Maternal smoking	NA	→	NA	→
2. Tonsillectomy	↑	↑	→	→	15. Breastfed (unclassified)	↓	↓	→	↓
3. Urban living	→	↑	→	↑	16. Breastfed (<6 mo)	NA	→	NA	→
4. Pets	↓	→	↓	↓	17. Breastfed (≥6 mo)	→	→	→	↓
5. Farm animals	↓	↓	↓	↓	18. Antibiotics (childhood)	↓	↑	→	→
6. HP infection	↓	↓	↓	↓	19. Antibiotics (unclassified)	→	↑	→	↑
7. Bed/bedroom sharing	↓	→	→	→	20. OCP	→	↑	→	↑
8. Multiple birth	↓	↓	↓	→	21. IBD family history	↑	↑	↑	↑
9. Physical activity	↓	↓	↓	→	22. Caesarean	NA	↑	NA	↑
10. Smoking (unclassified)	↑	↑	→	→	23. Isotretinoin	NA	→	NA	↑
11. Former smoking	↑	↑	↑	↑	24. NSAIDs and acetaminophen	→	→	→	→
12. Current smoking	→	↑	↓	↓	25. Parasite infection	NA	→	→	→
13. Passive smoking	→	→	→	→	26. Vaccination	→	→	↓	→

Note: ↓, decreased risk; ↑, increased risk; →, non-significant.
Abbreviations: HP, Helicobacter pylori; IBD, inflammatory bowel disease; NA, not applicable; NASAIDs, non-steroidal anti-inflammatory drugs; OCP, oral contraceptive.

Table 2. Summary of dietary factors for Crohn's disease (CD) and ulcerative colitis (UC)
Dietary factors	CD		UC		Dietary factors	CD		UC
Dietary factors	East	West	East	West	Dietary factors	East	West	East	West
1. Total energy	NA	↑	NA	↑	13. Meat and meat products	↑	↑	→	→
2. Carbohydrate	↓	→	→	→	14. Fish	→	↓	↑	→
3. Fat	↑	→	→	→	15. Vegetables	→	↓	→	→
4. Cholesterol	→	→	↑	→	16. Fruits	→	↓	↓	→
5. Fatty acids (unclassified)	↑	→	↑	→	17. Fibre	→	↓	→	→
6. SFA	→	→	↑	→	18. Alcohol	→	→	→	↓
7. MUFA	↑	→	↑	→	19. Coffee	→	→	↓	↓
8. PUFA	→	→	→	→	20. Soft drinks	→	↑	→	→
9. n-3 PUFA	↑	→	→	↓	21. Milk and dairy products	→	↓	→	→
10. n-6 PUFA	↑	→	→	↑	22. Tea	→	NA	→	NA
11. Eggs	→	→	↑	→	23. Vitamin D deficiency	→	↑	↑	↑
12. Protein	→	→	→	→

Note: ↓: decreased risk, ↑: increased risk, →: non-significant.
Abbreviations: FA, fatty acid; MUFA, monounsaturated fatty acid; NA, not applicable; PUFA, polyunsaturated fatty acid; SFA, saturated fatty acid.