Influence of methyl donor nutrients as epigenetic regulators in colorectal cancer: A systematic review of observational studies

Table 5 Summary of results of the studies included in this systematic review

Gen, SNP/CIMP/MSI	Nutrients/alcohol	CRC risk/CIMP+	Ref.
MTHFR 677 TT	Folate; Adequate folate	CRC risk; CRC risk	Guerreiro et al[24]; Sharp et al[29]; Ma et al[26]
	Alcohol	CRC risk	Chen et al[23]; Ma et al[26]
	Folate/Met, and without alcohol	CRC risk	Slattery et al[30]
	Vitamin B6	CRC risk	Sharp et al[29]
BRAF mutation	Folate	CRC risk (M)	de Vogel et al[37]
	Met	CRC risk (M)
hMLH1 hypermethylation	Vitamin B6	CRC risk (M)
MTHFR 1298 AC/CC	Folate/Met, and alcohol	CIMP+	Curtin et al[32]
MTHFR 1298 AA	Alcohol	CIMP+ (CCa)
p16 unmethylated, CIMPlow or BRAF mut	Alcohol	CRC risk	Slattery et al[36]
hMSH3, MSI or MMR status	Niacin	CRC risk (DCCa)	Kim et al[34]

BRAF: B-Raf proto-oncogene; CCa: Colon cancer; CRC: Colorectal cancer; CIMP: CpG island methylator phenotype; DCCa: Distal colon cancer; hMLH1: Human MutL homolog 1; hMSH3: Human MutS homolog 3; M: Men; Met: Methionine; MMR: Mismatch repair; MSI: Microsatellite instability; MTHFR: Methylenetetrahydrofolate reductase; mut: Mutation; SNP: Single-nucleotide polymorphism.

↑: High intake or increased risk or high probability.

↓: Low intake or increased risk.