Higher Dietary Fibre Intake Is Associated With Lower Risk of Inflammatory Bowel Disease

Prospective Cohort Study

Minzi Deng; Lintao Dan; Shuyu Ye; Xuejie Chen; Tian Fu; Xiaoyan Wang; Jie Chen

Aliment Pharmacol Ther. 2023;58(5):516-525.

Abstract and Introduction

Abstract

Background: Limited prospective studies that have examined the association of dietary fibre with IBD have provided inconsistent evidence.

Aim: To examine any associations between dietary fibre intake and subsequent incidence of IBD, Crohn's disease (CD) and ulcerative colitis (UC)

Methods: We conducted a prospective cohort study of 470,669 participants from the UK Biobank and estimated dietary fibre intake from a valid food frequency questionnaire at baseline. Incident IBD was ascertained from primary care data and inpatient data. Cox proportional hazard models were used to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs) for associations between dietary fibre intake and the risk of IBD, CD and UC.

Results: During an average follow-up of 12.1 years, we ascertained 1473 incident IBD cases, including 543 cases of CD and 939 cases of UC. Comparing the lowest quintiles, an inverse association was observed between dietary fibre intake and risk of IBD (HR 0.74, 95% CI 0.58–0.93, p = 0.011) and CD (HR 0.48, 95% CI 0.32–0.72, p < 0.001), but not UC (HR 0.92, 95% CI 0.69–1.24, p = 0.595). For specified sources, dietary fibre intake from fruit and bread decreased the risk of CD, while dietary fibre intake from cereal decreased the risk of UC.

Conclusions: Higher consumption of dietary fibre was associated with a lower risk of IBD and CD, but not UC. Our findings support current recommendations to increase the intake of dietary fibre.

Introduction

The prevalence of inflammatory bowel disease (IBD) has been increasing globally comprising two subtypes, Crohn's disease (CD) and ulcerative colitis (UC).^[1] As a crucial modifiable environmental risk factor, the diet has received widespread attention in the aetiopathogenesis of IBD.^[2] Among dietary nutrients, dietary fibre has several plausible biological mechanisms that may provide possibilities for the prevention of IBD, such as the production of short-chain fatty acid (SCFA), reduction of circulating inflammation markers, maintenance of the intestinal barrier and regulation of intestinal microbiota.^[3] Importantly, specified sources of dietary fibre delivered different health benefits based on solubility, viscosity and fermentability.^[4]

Although previously summarised evidence has pointed to an inverse association of dietary fibre intake with CD, not with UC,^[5–8] this evidence was evaluated to be of low or critically low quality in the latest umbrella meta-analysis.^[9] This is partly because most studies suffer from problems such as recall bias due to case–control designs and small sample sizes and need to be further confirmed by large prospective studies. However, to our knowledge, there is insufficient and conflicting evidence from prospective studies. Only one prospective study conducted in the two US female cohorts (Nurses' Health Studies ^NHS-I and NHS-II) reported a lower risk of CD for participants with high dietary fibre intake.^[10] However, in a related recent study, when these two cohorts were combined with another prospective male cohort (Health Professionals Follow-Up Study), dietary fibre only appeared to reduce the risk of ileocolonic CD, but not the risk of overall CD.^[11] Two large prospective studies from Europe reported a null association between dietary fibre and the development of IBD, raising concerns about the possibility of dietary fibre to prevent the development of IBD.^[12,13]

Therefore, to answer the questions (1) whether the inverse association between dietary fibre and IBD onset is stable and (2) the role of dietary fibre from different food sources on IBD onset, we systematically conducted a prospective cohort study in the UK Biobank to explore the associations between dietary fibre intake from fruit, vegetable, bread, and cereal sources and risk of IBD and IBD subtypes.

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Next Section

Table 1. Baseline characteristics of all participants based on quintiles of dietary fibre intake ^a.
	Total (n = 470,669)	Dietary fibre intake (g/d)
	Total (n = 470,669)	Q1 (0 to <9.3, n = 94,157)	Q2 (9.3 to <12.4, n = 94,274)	Q3 (12.4 to <15.2, n = 93,998)	Q4 (15.2 to <18.7, n = 94,140)	Q5 (18.7–45.7, n = 94,100)
Age, year	56.51 (8.08)	54.73 (8.27)	56.04 (8.17)	56.77 (8.02)	57.32 (7.85)	57.68 (7.77)
Sex (%)
Female	257,400 (54.7)	43,834 (46.6)	51,489 (54.6)	54,567 (58.1)	55,358 (58.8)	52,152 (55.4)
Male	213,269 (45.3)	50,323 (53.4)	42,785 (45.4)	39,431 (41.9)	38,782 (41.2)	41,948 (44.6)
TDI	−1.37 (3.05)	−0.87 (3.28)	−1.41 (3.01)	−1.55 (2.95)	−1.59 (2.92)	−1.41 (3.03)
Education (%)
Below college	310,699 (66.6)	69,353 (74.4)	62,898 (67.3)	60,633 (65.0)	59,137 (63.4)	58,678 (63.0)
College and above	155,719 (33.4)	23,895 (25.6)	30,564 (32.7)	32,583 (35.0)	34,190 (36.6)	34,487 (37.0)
Ethnicity (%)
White	445,904 (95.0)	88,254 (94.0)	89,430 (95.1)	89,810 (95.8)	89,941 (95.8)	88,469 (94.4)
Others	23,281 (5.0)	5618 (6.0)	4570 (4.9)	3908 (4.2)	3895 (4.2)	5290 (5.6)
Smoking status (%)
Current smokers	48,526 (10.3)	18,449 (19.7)	10,103 (10.7)	7755 (8.3)	6326 (6.7)	5893 (6.3)
Ex-smokers	162,633 (34.7)	29,564 (31.5)	32,266 (34.3)	32,780 (35.0)	33,324 (35.5)	34,699 (37.0)
Never smoked	258,013 (55.0)	45,828 (48.8)	51,613 (54.9)	53,202 (56.8)	54,203 (57.8)	53,167 (56.7)
Physical activity (%)
Inadequate	141,443 (30.1)	37,697 (40.0)	30,621 (32.5)	27,361 (29.1)	24,703 (26.2)	21,061 (22.4)
Adequate	329,226 (69.9)	56,460 (60.0)	63,653 (67.5)	66,637 (70.9)	69,437 (73.8)	73,039 (77.6)
Alcohol consumption (%)
None to moderate	374,189 (79.5)	69,171 (73.5)	73,526 (78.0)	75,410 (80.3)	77,390 (82.2)	78,692 (83.7)
Heavy	96,222 (20.5)	24,906 (26.5)	20,692 (22.0)	18,558 (19.7)	16,711 (17.8)	15,355 (16.3)
BMI, kg/m²	27.40 (4.78)	27.76 (4.88)	27.52 (4.78)	27.34 (4.72)	27.20 (4.71)	27.17 (4.80)
CCI, scores	0.27 (0.90)	0.28 (0.92)	0.26 (0.89)	0.27 (0.91)	0.27 (0.89)	0.28 (0.90)
Fibre intake, g/d	14.25 (5.91)	6.79 (1.92)	10.89 (0.88)	13.74 (0.81)	16.82 (1.02)	23.02 (4.24)
Fibre from vegetable, g/d	4.86 (3.23)	1.88 (1.37)	3.50 (1.69)	4.67 (2.00)	5.89 (2.36)	8.36 (3.70)
Fibre from fruits, g/d	4.86 (2.97)	2.70 (1.41)	3.93 (1.58)	4.60 (1.84)	5.36 (2.19)	7.70 (4.20)
Fibre from bread, g/d	2.44 (1.93)	1.50 (1.06)	2.05 (1.42)	2.43 (1.67)	2.82 (1.97)	3.42 (2.59)
Fibre from cereal, g/d	2.09 (2.10)	0.70 (0.92)	1.42 (1.40)	2.04 (1.76)	2.74 (2.13)	3.54 (2.57)

Abbreviations: BMI, body mass index; CCI, Charlson Comorbidity Index; CD, Crohn's disease; IBD, inflammatory bowel disease; TDI, Townsend deprivation index; UC, ulcerative colitis.
^aContinuous variables are displayed as means (SDs), and categorical variables are displayed as numbers (percentages).

Table 2. Associations between dietary fibre intake in quintiles and risk of IBD.
Dietary fibre intake in quintiles, g/d	IBD
Dietary fibre intake in quintiles, g/d	Cases/person-years	HR (95% CI)^a	p	HR (95% CI)^b	p
Fibre intake
Q1 (0 to <9.3)	391/1,132,614	Ref		Ref
Q2 (9.3 to <12.4)	297/1,141,235	0.74 (0.64, 0.87)	<0.001	0.81 (0.69, 0.95)	0.010
Q3 (12.4 to <15.2)	281/1,139,312	0.70 (0.60, 0.82)	<0.001	0.79 (0.66, 0.93)	0.006
Q4 (15.2 to <18.7)	281/1,142,099	0.69 (0.59, 0.81)	<0.001	0.79 (0.66, 0.95)	0.014
Q5 (18.7–45.7)	267/1,139,408	0.65 (0.56, 0.76)	<0.001	0.74 (0.58, 0.93)	0.011
p-trend^c			<0.001		0.025
Fruit fibre intake
Q1 (0 to <2.0)	441/1,445,572	Ref		Ref
Q2 (2.0 to <4.0)	398/1,360,229	1.01 (0.88, 1.16)	0.914	1.10 (0.95, 1.27)	0.192
Q3 (4.0 to <5.0)	141/675,435	0.75 (0.62, 0.91)	0.004	0.88 (0.72, 1.08)	0.235
Q4 (5.0 to <7.0)	252/1,139,840	0.78 (0.66, 0.92)	0.002	0.89 (0.74, 1.07)	0.209
Q5 (7.0–42.0)	285/1,073,592	0.93 (0.79, 1.09)	0.383	1.10 (0.89, 1.36)	0.396
p-trend			0.318		0.799
Vegetable fibre intake
Q1 (0 to <3.0)	552/1,912,219	Ref		Ref
Q2 (3.0 to <4.0)	304/1,158,761	0.94 (0.82, 1.08)	0.398	0.98 (0.85, 1.14)	0.835
Q3 (4.0 to <5.0)	203/826,881	0.88 (0.75, 1.04)	0.136	0.93 (0.78, 1.11)	0.410
Q4 (5.0 to <6.0)	176/665,715	0.95 (0.80, 1.13)	0.577	1.00 (0.82, 1.22)	0.996
Q5 (6.0–40.0)	282/1,131,092	0.89 (0.77, 1.04)	0.139	0.96 (0.76, 1.22)	0.755
p-trend			0.020		0.504
Bread fibre intake
Q1 (0 to <1.0)	370/1,265,687	Ref		Ref
Q2 (1.0 to <1.5)	299/1,103,688	0.93 (0.80, 1.09)	0.382	0.94 (0.81, 1.10)	0.443
Q3 (1.5 to <2.6)	371/1,427,166	0.88 (0.76, 1.02)	0.090	0.90 (0.78, 1.04)	0.165
Q4 (2.6 to <3.6)	206/904,595	0.76 (0.60, 0.95)	0.018	0.80 (0.67, 0.95)	0.012
Q5 (3.6–36.6)	271/993,532	0.78 (0.65, 0.92)	0.004	0.85 (0.75, 0.96)	0.010
p-trend			0.002		0.047
Cereal fibre intake
Q1 (0 to <0.2)	379/1,242,460	Ref		Ref
Q2 (0.2 to <1.0)	309/1,033,543	0.99 (0.85, 1.15)	0.854	1.02 (0.88, 1.19)	0.766
Q3 (1.0 to <3.9)	335/1,240,377	0.92 (0.79, 1.07)	0.301	1.01 (0.86, 1.17)	0.947
Q4 (1.9 to <3.6)	252/1,044,808	0.82 (0.70, 0.97)	0.018	0.89 (0.76, 1.05)	0.178
Q5 (3.6–30.1)	242/1,133,480	0.73 (0.62, 0.87)	<0.001	0.84 (0.71, 0.99)	0.036
p-trend			<0.001		0.011

Abbreviations: CI confidence interval; HR, hazard ratio; IBD, inflammatory bowel disease.
Number in bold represent a p value <0.05.
^aMinimally adjusted model: adjusted for age, sex and ethnicity.
^bFully adjusted model: adjusted for age, sex, ethnicity, smoking status, physical activity, BMI alcohol consumption, Townsend deprivation index, Charlson Comorbidity Index, and major food groups (fruit, vegetables, fish, meat, bread and cereal).
^c p-trend was estimated using the median value of each category.

Table 3. Associations between dietary fibre intake in quintiles and risk of CD and UC.
Dietary fibre intake in quintiles, g/d	CD					UC
Dietary fibre intake in quintiles, g/d	Cases/person-years	HR (95% CI)^a	p	HR (95% CI)^b	p	Cases/person-years	HR (95% CI)^a	p	HR (95% CI)^b	p
Fibre intake
Q1 (0 to <9.3)	158/1,134,900	Ref		Ref		233/1,134,365	Ref		Ref
Q2 (9.3 to <12.4)	97/1,143,996	0.60 (0.47, 0.77)	<0.001	0.65 (0.50, 0.85)	0.001	200/1,143,319	0.84 (0.70, 1.02)	0.075	0.92 (0.76, 1.13)	0.433
Q3 (12.4 to <15.2)	89/1,142,316	0.55 (0.42, 0.71)	<0.001	0.60 (0.45, 0.80)	<0.001	192/1,141,758	0.80 (0.66, 0.97)	0.026	0.92 (0.74, 1.13)	0.419
Q4 (15.2 to <18.7)	109/1,145,772	0.66 (0.52, 0.85)	0.001	0.71 (0.53, 0.96)	0.028	172/1,145,311	0.71 (0.58, 0.87)	0.001	0.84 (0.66, 1.06)	0.140
Q5 (18.7–45.7)	81/1,143,731	0.49 (0.37, 0.64)	<0.001	0.48 (0.32, 0.72)	<0.001	186/1,143,144	0.76 (0.63, 0.92)	0.006	0.92 (0.69, 1.24)	0.595
p-trend^c			<0.001		0.013			0.001		0.327
Fruit fibre intake
Q1 (0 to <2.0)	166/1,448,940	Ref		Ref		275/1,448,206	Ref		Ref
Q2 (2.0 to <4.0)	134/1,364,066	0.90 (0.72, 1.14)	0.393	1.00 (0.78, 1.27)	0.970	264/1,363,278	1.07 (0.90, 1.27)	0.440	1.16 (0.97, 1.39)	0.099
Q3 (4.0 to <5.0)	57/677,309	0.81 (0.59, 1.10)	0.173	0.96 (0.69, 1.33)	0.799	84/677,045	0.72 (0.56, 0.92)	0.009	0.84 (0.64, 1.09)	0.190
Q4 (5.0 to <7.0)	80/1,143,174	0.66 (0.50, 0.87)	0.003	0.75 (0.55, 1.02)	0.066	172/1,142,635	0.85 (0.70, 1.04)	0.116	0.98 (0.78, 1.22)	0.836
Q5 (7.0–42.0)	97/1,077,226	0.71 (0.57, 0.88)	0.002	0.79 (0.64, 0.98)	0.032	188/1,076,733	0.99 (0.81, 1.20)	0.887	1.18 (0.90, 1.54)	0.221
p-trend			0.003		0.014			0.934		0.205
Vegetable fibre intake
Q1 (0 to <3.0)	199/1,915,822	Ref		Ref		353/1,914,802	Ref		Ref
Q2 (3.0 to <4.0)	102/1,161,571	0.89 (0.70, 1.13)	0.340	0.93 (0.72, 1.20)	0.592	202/1,160,889	0.97 (0.81, 1.15)	0.727	1.01 (0.84, 1.22)	0.892
Q3 (4.0 to <5.0)	79/829,149	0.97 (0.75, 1.27)	0.835	1.01 (0.76, 1.35)	0.921	124/828,865	0.83 (0.68, 1.03)	0.087	0.88 (0.70, 1.10)	0.270
Q4 (5.0 to <6.0)	58/668,294	0.89 (0.66, 1.20)	0.434	0.92 (0.66, 1.28)	0.617	118/667,966	0.99 (0.80, 1.22)	0.905	1.05 (0.82, 1.34)	0.709
Q5 (6.0–40.0)	96/1,135,879	0.86 (0.67, 1.11)	0.259	0.88 (0.60, 1.30)	0.530	186/1,135,375	0.91 (0.76, 1.09)	0.315	1.01 (0.76, 1.35)	0.941
p-trend			0.174		0.149			0.056		0.836
Bread fibre intake
Q1 (0 to <1.0)	146/1,269,496	Ref		Ref		224/1,269,041	Ref		Ref
Q2 (1.0 to <1.5)	102/1,107,044	0.81 (0.63, 1.04)	0.100	0.82 (0.63, 1.05)	0.117	197/1,106,386	1.02 (0.84, 1.23)	0.870	1.02 (0.85, 1.24)	0.807
Q3 (1.5 to <2.6)	134/1,430,954	0.81 (0.64, 1.03)	0.080	0.83 (0.65, 1.05)	0.121	237/1,430,341	0.93 (0.77, 1.12)	0.436	0.95 (0.79, 1.14)	0.583
Q4 (2.6 to <3.6)	65/907,104	0.62 (0.46, 0.84)	0.002	0.65 (0.48, 0.87)	0.004	141/906,657	0.88 (0.71, 1.08)	0.220	0.90 (0.73, 1.12)	0.340
Q5 (3.6–36.6)	87/996,116	0.76 (0.60, 0.95)	0.018	0.75 (0.57, 0.98)	0.035	184/995,472	1.01 (0.83, 1.24)	0.899	1.06 (0.87, 1.30)	0.563
p-trend			0.007		0.021			0.615		0.984
Cereal fibre intake
Q1 (0 to <0.2)	132/1,246,017	Ref		Ref		247/1,245,313	Ref		Ref
Q2 (0.2 to <1.0)	109/1,036,587	1.01 (0.78, 1.30)	0.951	1.07 (0.83, 1.38)	0.614	200/1,035,950	0.97 (0.81, 1.17)	0.784	1.00 (0.83, 1.21)	0.997
Q3 (1.0 to <3.9)	121/1,242,559	0.99 (0.76, 1.27)	0.909	1.11 (0.86, 1.44)	0.413	214/1,242,006	0.89 (0.74, 1.08)	0.230	0.95 (0.79, 1.15)	0.602
Q4 (1.9 to <3.6)	86/1,048,192	0.83 (0.63, 1.09)	0.183	0.93 (0.71, 1.23)	0.631	166/1,047,675	0.82 (0.67, 1.00)	0.049	0.87 (0.71, 1.07)	0.184
Q5 (3.6–30.1)	86/1,137,361	0.78 (0.59, 1.03)	0.074	0.92 (0.69, 1.23)	0.579	156/1,136,953	0.71 (0.58, 0.87)	0.001	0.79 (0.64, 0.98)	0.029
p-trend			0.046		0.449			<0.001		0.010

Abbreviations: CD, Crohn's disease; CI confidence interval; HR, hazard ratio; IBD, inflammatory bowel disease; UC, ulcerative colitis.
Number in bold represent a p value <0.05.
^aMinimally adjusted model: adjusted for age, sex and ethnicity.
^bFully adjusted model: adjusted for age, sex, ethnicity, smoking status, physical activity, alcohol consumption, Townsend deprivation index, Charlson Comorbidity Index and major food groups (fruit, vegetables, fish, meat, bread and cereal).
^c p-trend was estimated using the median value of each category.