Table 4.

Epidemiological studies on cruciferous vegetables and colorectal cancer.

The characteristic of participants	Dietary specifications	Follow-up	Main outcomes	References
Netherlands cohort study on diet and cancer; 62,573 women and 58,279 men aged 55–69 years	Cruciferous vegetables	6.3 years	While cruciferous vegetables have a strong negative association with colon cancer in both genders, they have been reported to increase the risk of rectal cancer in women.	[17]
Singapore Chinese Health Study; 213 cases and 1194 controls	Cruciferous vegetables	5 years	Isothiocyanates derived from cruciferous vegetables reduced the risk of colorectal cancer in individuals with low glutathione S-transferases.	[23]
The Western Australian Bowel Health Study; 834 colorectal cancer cases and 939 controls	Brassica vegetable	2 years	Brassica vegetables were found to be inversely related with proximal colon cancer.
A hospital-based matched case-control study in northeast China; 833 colorectal cancer cases and 833 controls	Cruciferous vegetables	28 months	There was not a significant association between total cruciferous vegetable intake and colorectal cancer risk. In the stratification analysis by gender, higher consumption of total cruciferous vegetables in women was seen to be associated with a reduced risk of colorectal cancer.	[53]
150 colorectal cancer cases and 300 controls	Cruciferous vegetables	10 months	Cruciferous vegetables (broccoli OR = 0.11, cauliflower OR = 0.30, and cabbage OR = 0.30) were found as one of the most significant protective factors in decreasing the risk of colorectal cancer.	[52]
2390 colorectum cancer cases and 11492 controls	Cruciferous vegetables	Case–control studies in Italy and Switzerland between 1991 and 2009	Subjects who consumed at least one portion of cruciferous vegetables per week had a significantly lower risk of colorectal cancer compared to those who never or occasionally consumed them (OR = 0.83).	[51]
Chinese in Singapore; 203 colorectal cancer cases and 425 controls	Cruciferous vegetables	26 months	A protective effect of high cruciferous vegetable intake was observed in cancers of the colon and rectum combined (OR = 0.50), colon cancer, and rectal cancer (OR = 0.51).	[54]
231 colon cancer cases and 391 controls	Cruciferous vegetables	Case-control study in Utah between July 1979 and June 1983	There was an association between high cruciferous vegetable consumption and colon cancer protection in males.	[55]
163 colorectal cancer cases and 326 healthy controls	Cruciferous vegetables	Cases between 1982 and 1993	Cruciferous vegetables exhibited a significant inverse association (OR, 0.59) with cancer.	[56]
29,133 Finnish men aged 50–69 years	Cruciferous vegetables	8 years	Consumption of cruciferous vegetables was positively related to the risk of colorectal cancer.	[57]
A cohort of 17,633 white males aged 35 and older		20 years of follow-up	No clear risk patterns in terms of colon and colorectal cancer were seen for cruciferous vegetables.	[58]

OR: odds ratio.