Phytochemically rich dietary components and the risk of colorectal cancer: A systematic review and meta-analysis of observational studies

Table 1 Association between dietary components and colorectal cancer risk

Dietary component		Number of studies (number of publications)1	Pooled OR (95%CI)	P value	Heterogeneity [I2 (%)]	Egger P value
Cruciferous vegetables	All	61 (33)	0.90 (0.85-0.95)	0.00	31.02	0.58
	Case-control	38 (21)	0.85 (0.78-0.93)	0.00	41.94
	Cohort	23 (12)	0.94 (0.89-1.00)	0.07	0.00
Citrus fruits	All	20 (12)	0.90 (0.84-0.96)	0.00	21.65	0.46
	Case-control	9 (7)	0.94 (0.85-1.04)	0.00	42.81
	Cohort	11 (5)	0.86 (0.77-0.95)	0.26	0.00
Garlic	All	14 (10)	0.83 (0.76-0.91)	0.00	32.64	0.12
	Case-control	8 (6)	0.92 (0.72-1.18)	0.00	47.80
	Cohort	6 (4)	0.81 (0.72-0.90)	0.51	35.38
Tomatoes	All	16 (11)	0.89 (0.84-0.95)	0.00	0.00	0.02
	Case-control	13 (9)	0.97 (0.84-0.95)	0.00	0.00
	Cohort	3 (2)	0.87 (0.8-0.93)	0.68	0.00
Nuts	All	9 (7)	0.72 (0.50-1.03)	0.07	91.85	0.22
	Case-control	5 (4)	0.74 (0.39-1.43)	0.38	94.35
	Cohort	4 (3)	0.74 (0.58-0.94)	0.01	35.48

¹Where studies reported gender-specific or cancer site-specific results only rather than combining these into one result, we included effect size for male and female participants separately and likewise site-specific cancer data separately, and these are therefore displayed as 2 separate studies in the accompanying forest plots, despite originating from the same publication. CI: Confidence interval; OR: Odds ratio.