Table 2.

Relationship between dietary folate, methionine, vitamin B6, and risk of prostate cancer among 1,294 cases and 1,451 controls in Italy, 1991-2002

Approximated quintile* of intake
p for trendContinuous OR
1 (low)2345 (high)
Folate intake
    Cases/controls291:290244:290277:291265:290217:290
    OR (95% CI)§10.84 (0.66-1.08)0.87 (0.68-1.11)0.85 (0.66-1.08)0.66 (0.51-0.85)0.0050.92 (0.85-0.99)
Methionine intake
    Cases/controls245:291240:289240:290282:290287:291
    OR (95% CI)§10.99 (0.77-1.27)0.96 (0.75-1.24)1.13 (0.88-1.44)1.15 (0.89-1.48)0.151.04 (0.97-1.12)
Vitamin B6
    Cases/controls260:291266:290269:290247:290252:290
    OR (95% CI)§11.00 (0.78-1.28)0.99 (0.77-1.27)0.85 (0.66-1.09)0.95 (0.74-1.22)0.340.95 (0.88-1.03)
  • * Folate, methionine, and vitamin B6 intake were energy adjusted using the residual method.

  • The measurement unit was set at 1 SD of the distribution of controls, calculated on the residual values. For absolute intakes, the SD values were 78.56 μg/d for folate, 637.07 mg/d for methionine, and 0.53 mg/d for vitamin B6.

  • Cutpoints for quintiles of absolute folate intake (nonresidual) were 196, 234, 270, and 316 μg/d; corresponding values for methionine were 1580, 1882, 2174, and 2557 mg/d, and for vitamin B6 were 1.49, 1.76, 1.99, and 2.32 mg/d.

  • § Estimates from unconditional logistic regression models adjusted for age, study center, education, body mass index, alcohol consumption, smoking habit, family history of prostate cancer, and nonalcohol energy intake. The reference category was the first (lowest) quintile of intake.