Table 1.

Association of folic acid treatment, baseline dietary intake, and circulating levels of folate with risk of subsequent prostate cancer^*

Risk factor	Adjusted for age		Adjusted for multiple factors
	HR (95% CI)†	P value†	HR (95% CI)	P value
Folic acid supplementation	2.63 (1.23 to 5.65)	.01	2.58 (1.14 to 5.86)‡	.02
Dietary folate§	0.70 (0.48 to 1.04)	.08	0.65 (0.35 to 1.20)‖	.17
Nonmultivitamin users	0.77 (0.50 to 1.19)	.24	0.70 (0.37 to 1.33)‖	.28
Multivitamin users	0.53 (0.21 to 1.32)	.17	0.49 (0.18 to 1.36)‖	.17
Plasma folate¶	0.56 (0.32 to 0.98)	.04	0.68 (0.35 to 1.30)#	.25
Nonmultivitamin users	0.41 (0.18 to 0.96)	.04	0.42 (0.17 to 1.04)#	.06
Multivitamin users	1.01 (0.55 to 1.86)	.97	1.11 (0.58 to 2.15)#	.75
Red blood cell folate**	0.82 (0.57 to 1.17)	.27	1.19 (0.77 to 1.83)#	.43
Nonmultivitamin users	0.73 (0.46 to 1.16)	.18	0.91 (0.54 to 1.53)#	.64
Multivitamin users	1.81 (0.95 to 3.45)	.07	2.04 (1.08 to 3.87)#	.03

^*Cox proportional hazard models were used to obtain hazard ratios and 95% confidence intervals. HR = hazard ratio; CI = 95% confidence interval.

^†Adjusted for age. For dietary folate, also adjusted by baseline total caloric intake.

^‡Adjusted for age; aspirin treatment group; alcohol use; baseline multivitamin use; and plasma levels of vitamins B₂, B₆, and B₁₂.

^§HR per one SD of the residual of the log-log–transformed dietary folate (SD = 0.4) using methods described in the text.

^‖Adjusted for age; alcohol use; aspirin treatment group; baseline multivitamin use; dietary intake (foods only) of calories, B₂, and B₆; and folic acid treatment group.

^¶HR per one SD of the level of plasma folate (SD = 18 nmol/L).

^#Adjusted for age; alcohol use; aspirin treatment group; baseline multivitamin use; plasma levels of B₂, B₆, and B₁₂; and folic acid treatment group.

^**HR per one SD of the level of red blood cell folate (SD = 142 nmol/L).