Table 2.

The main adjusted factors of studies included in the meta-analysis

Ref.	Adjusted confounders
	Age	Sex	Energy intake	BMI	Family history of CRC	Alcohol use	Smoking status	Physical activity	Education level	Red meat
Lee et al[39], 2017	√		√	√		√		√	√	√
Leenders et al[40], 2015				√		√	√	√
Abu Mweis et al[41], 2015	√	√	√		√		√		√
Tayyem et al[42], 2014	√	√	√		√		√	√	√
Rosato et al[43], 2013	√	√	√		√	√			√
Vogtmann et al[50], 2013	√		√	√	√	√	√	√	√	√
Annema et al[44], 2011	√	√	√	√		√	√	√
Foschi et al[45], 2010	√	√	√	√		√	√	√	√
Li et al[51], 2010	√	√	√	√	√	√	√	√	√
Jedrychowski et al[32], 2010	√	√	√				√
Williams et al[46], 2009	√	√	√	√	√			√	√
Nomura et al[52], 2008	√		√	√	√	√	√	√		√
Gallus et al[47], 2005	√	√	√	√		√	√	√	√
Lin et al[55], 2005	√		√	√	√	√	√	√		√
Satia-Abouta et al[48], 2004	√	√	√	√	√		√	√	√
Voorrips et al[53], 2000	√				√	√
Michels et al[54], 2000	√		√	√	√	√	√	√		√
Franceschi et al[29], 1998	√	√	√					√	√
Levi et al[49], 1999	√	√	√	√		√	√	√	√
Le Marchand et al[56], 1997	√		√		√	√	√
Deneo-Pellegrini et al[57], 1996	√	√	√	√		√			√
Lin et al[55], 2005	√		√	√	√	√	√	√		√
Theodoratou et al[37], 2007	√	√	√	√	√	√	√	√
Deneo-Pellegrini et al[38], 2002	√		√	√	√				√	√

BMI: Body mass index; CRC: Colorectal cancer.