TABLE 3.

Association between genomic DNA methylation in colonic mucosa, MTHFR 677C>T genotype, and biomarkers of folate status¹

	Unadjusted coefficient (95% CI)	P2	Adjusted coefficient (95% CI)3	P2
MTHFR 677C>T
CC (reference)
CT	−0.0188 (−0.0570, 0.0194)	0.33	−0.0237 (−0.0639, 0.0165)4	0.25
TT	−0.0204 (−0.0929, 0.0520)	0.58	−0.0241 (−0.1024, 0.0541)4	0.55
Serum folate (nmol/L)	0.0003 (−0.0010, 0.0015)	0.70	0.0002 (−0.0012, 0.0169)	0.75
Red blood cell folate (nmol/L)	−0.0001 (−0.0001, −0.0000)	0.04	−0.0001 (−0.0001, 0.0000)	0.07
Colonic tissue folate (nmol/g tissue)	0.0091 (−0.0175, 0.0357)	0.50	0.0198 (−0.0007, 0.0403)	0.06
Plasma homocysteine (μmol/L)	0.0008 (−0.0017, 0.0034)	0.54	0.0009 (−0.0020, 0.0039)	0.62

¹Generalized linear model with a logit link (the natural log of the odds: log). For the continuous predictor variables (biomarkers of folate status), the coefficient gives the amount of change in the log odds of having high methylation for each unit increase in the biomarker (ie, a positive coefficient suggests an increase in the odds, whereas a negative coefficient suggests a decrease in the odds of having high methylation with increasing biomarker concentration). For the categorical predictor variable (MTHFR 677C>T), the coefficient gives the log odds of having high methylation in the CT or TT genotype compared with the CC genotype (reference group), ie, a negative coefficient suggests a decrease in the odds of having high methylation in individuals carrying the CT or TT genotype compared with individuals carrying the CC genotype.

²Threshold for significance using Bonferroni correction for 8 repeated tests is P = 0.006.

³Adjusted for age, sex (male or female), ethnicity (white or nonwhite), supplement use (user or nonuser), serum vitamin B-12, and MTHFR 677C>T genotype.

⁴Adjusted for age, sex (male or female), ethnicity (white or nonwhite), supplement use (user or nonuser), and serum vitamin B-12.