Table 3.

 Subgroup analyses of fibre intake and risk of colorectal cancer, dose-response analysis

Subgroups	Total dietary fibre						Fruit fibre						Vegetable fibre
	No of studies	Relative risk (95% CI)	I2 (%)	P for heterogeneity			No of studies	Relative risk (95% CI)	I2 (%)	P for heterogeneity			No of studies	Relative risk (95% CI)	I2 (%)	P for heterogeneity
				*	†					*	†					*		†
All studies	16	0.90 (0.86 to 0.94)	0	0.48	—		9	0.93 (0.82 to 1.05)	23	0.24	—		9	0.98 (0.91 to 1.06)	0	0.60		—
Duration of follow-up:
<10 years	10	0.91 (0.84 to 0.97)	33.2	0.14	0.77		6	0.97 (0.82 to 1.14)	37.6	0.16	0.26		6	0.96 (0.88 to 1.04)	0	0.51		0.27
≥10 years	6	0.91 (0.85 to 0.98)	0	0.97			3	0.80 (0.64 to 1.00)	0	0.91			3	1.10 (0.90 to 1.35)	0	0.74
Sex:
Men	7	0.92 (0.82 to 1.03)	54.4	0.04	0.72		2	0.83 (0.72 to 0.97)	0	0.80	0.45		2	0.94 (0.78 to 1.14)	44.3	0.18		0.34
Women	11	0.94 (0.89 to 0.99)	0	0.74			5	0.91 (0.78 to 1.06)	0	0.80			5	1.02 (0.89 to 1.17)	0	0.54
Subsite:
Colon	13	0.90 (0.83 to 0.98)	33.9	0.11	0.86		3	0.90 (0.34 to 2.38)	59.2	0.42	0.85		3	0.89 (0.57 to 1.40)	30.9	0.24		0.24
Rectum	10	0.91 (0.83 to 1.03)	14.7	0.31			1	1.26 (0.09 to 18.24)	—	—			1	6.40 (0.97 to 42.34)	—	—
Geographical location:
Europe	4	0.87 (0.78 to 0.96)	9.2	0.35	0.74		2	0.75 (0.46 to 1.23)	0	0.39	0.34		2	1.30 (0.35 to 4.84)	58.2	0.12		0.70
USA	9	0.92 (0.88 to 0.96)	0	0.69			6	0.93 (0.81 to 1.07)	38.0	0.15			6	0.98 (0.91 to 1.06)	0	0.61
Asia	3	0.78 (0.60 to 1.03)	24.7	0.29			1	1.90 (0.40 to 9.04)	—	—			1	0.71 (0.26 to 1.91)	—	—
No of cases:
<500	8	0.92 (0.82 to 1.03)	0	0.64	0.35		4	1.08 (0.73 to 1.60)	0	0.87	0.98		4	1.05 (0.61 to 1.79)	8.0	0.35		0.37
500-1499	5	0.92 (0.87 to 0.99)	0	0.68			2	0.80 (0.64 to 1.00)	0	0.70			2	1.09 (0.89 to 1.34)	0	0.93
≥1500	3	0.88 (0.80 to 0.97)	64.0	0.06			3	0.94 (0.75 to 1.17)	71.4	0.03			3	0.96 (0.88 to 1.04)	0	0.41
Range of intake:
<15 to <10 g/day‡	11	0.90 (0.84 to 0.96)	11.9	0.33	0.80		6	1.07 (0.94 to 1.23)	0	0.61	0.04		6	1.03 (0.89 to 1.18)	0	0.58		0.54
≥15 to ≥10 g/day‡	5	0.90 (0.85 to 0.95)	0	0.51			3	0.86 (0.77 to 0.96)	0	0.71			3	0.96 (0.88 to 1.05)	0	0.38
Adjustment for confounders
Alcohol:
Yes	12	0.87 (0.83 to 0.92)	0	0.63	0.08		7	0.86 (0.78 to 0.96)	0	0.75	0.04		7	0.95 (0.87 to 1.04)	0	0.75	0.32
No	4	0.95 (0.88 to 1.01)	0	0.51			2	1.10 (0.95 to 1.28)	0	0.75			2	1.34 (0.54 to 3.34)	45.0	0.18
Smoking:
Yes	13	0.90 (0.85 to 0.95)	15.7	0.29	0.84		8	0.92 (0.81 to 1.05)	32.5	0.17	0.89		8	0.98 (0.90 to 1.05)	0	0.74	0.20
No	3	0.95 (0.88 to 1.01)	0	0.51			1	0.97 (0.45 to 2.09)	—	—			1	3.15 (0.63 to 15.64)	—	—
Body mass index, weight, waist to hip ratio:
Yes	10	0.89 (0.83 to 0.95)	19.4	0.26	0.22		7	0.86 (0.78 to 0.96)	0	0.75	0.04		7	0.95 (0.87 to 1.04)	0	0.75	0.32
No	6	0.93 (0.87 to 1.00)	0	0.91			2	1.10 (0.95 to 1.28)	0	0.75			2	1.34 (0.54 to 3.34)	45.0	0.18
Physical activity:
Yes	11	0.90 (0.85 to 0.96)	27.7	0.18	0.70		7	0.91 (0.79 to 1.05)	40.0	0.13	0.56		7	0.95 (0.87 to 1.04)	0	0.75	0.77
No	5	0.92 (0.85 to 0.99)	0	0.97			2	1.06 (0.68 to 1.65)	0	0.79			2	1.34 (0.54 to 3.34)	45.0	0.18
Red, processed meat:
Yes	10	0.89 (0.84 to 0.95)	21.3	0.25	0.32		9	0.93 (0.82 to 1.05)	23	0.24	NC		9	0.98 (0.91 to 1.06)	0	0.60	NC
No	6	0.93 (0.87 to 1.00)	0	0.86			0	—	—	—			0	—	—	—
Dairy products, calcium:
Yes	10	0.93 (0.87 to 0.98)	9.6	0.35	0.20		7	0.94 (0.82 to 1.07)	32.2	0.18	0.35		7	0.98 (0.91 to 1.06)	0	0.51	0.81
No	6	0.87 (0.82 to 0.92)	0	0.74			2	0.69 (0.40 to 1.19)	0	0.58			2	0.94 (0.42 to 2.07)	8.0	0.30
Folate:
Yes	7	0.89 (0.82 to 0.95)	41.3	0.12	0.27		6	0.90 (0.77 to 1.06)	49.9	0.08	0.60		6	0.98 (0.90 to 1.05)	0	0.62	0.59
No	9	0.93 (0.87 to 1.00)	0	0.94			3	1.04 (0.69 to 1.56)	0	0.93			3	1.33 (0.61 to 2.87)	21.7	0.28
Energy intake:
Yes	11	0.90 (0.84 to 0.96)	27.3	0.18	0.62		9	0.93 (0.82 to 1.05)	23	0.24	NC		9	0.98 (0.91 to 1.06)	0	0.60	NC
No	5	0.92 (0.86 to 0.98)	0	0.98			0	—	—	—			0	—	—	—

NC=not calculable.

*Within each subgroup.

†Between subgroups with meta-regression analysis.

‡Total dietary fibre: ≥15 v <15 g/day, fruit and vegetable fibre: ≥10 v <10 g/day.