TABLE 5.

Multiple linear regression analysis of inverse normal transformed formate concentration against metabolites adjusted for sex. The t-values are t-distributed statistic values to test the regression coefficients to be 0 and the (Pr  >  |t|) are the related P-values¹

Variable	Estimate	SE	t Value	Pr > |t|
Intercept	−0.9433087411	0.23224020	−4.06	<0.0001
Sex	−0.1693615946	0.05434786	−3.12	0.0019
Glycine	−0.0016462631	0.00044307	−3.72	0.0002
Serum vitamin B-12	−0.0006902293	0.00016918	−4.08	<0.0001
Serine	0.0062076509	0.00123529	5.03	<0.0001
Serum folate	0.0071649768	0.00167058	4.29	<0.0001
Tryptophan	0.0085507021	0.00198087	4.32	<0.0001
Choline	0.0342071342	0.01331375	2.57	0.0103

¹The formate concentration is transformed by inverse normal rank transformation to satisfy normality. Smoking, alcohol intake, red blood cell folate, total homocysteine, and oral contraceptive use were found not to be significantly associated with the inverse normal transformed formate concentrations; hence, they are not included in the final models.