Table 5.

Multivariate HR and 95% CI according to low/high joint intake of nitrite or nitrate and vitamin C and glioma risk

Joint intake Nitrite and/or nitrate/vitamin CLow/highLow/lowHigh/highHigh/lowP for joint interaction
Nitrite, total, median intake*0.550.550.770.77
Dietary vitamin C, median intake*1165311653
    No. of cases133155175122
    Multivariate HR1.000.851.010.880.88
    95% CI(Reference)0.67–1.080.81–1.270.69–1.13
Nitrite, plant sources, median intake*0.320.320.540.54
Dietary vitamin C, median intake*1165311653
    No. of cases125164183113
    Multivariate HR1.000.770.930.910.16
    95% CI(Reference)0.61–0.980.74–1.180.71–1.18
    Males
        No. of cases8712911885
        Multivariate HR1.000.781.000.970.29
        95% CI(Reference)0.59–1.030.76–1.320.72–1.31
Nitrate, total, median intake*27.427.463.563.5
Dietary vitamin C, median intake*1165311653
    No. of cases100174208103
    Multivariate HR1.000.891.171.070.87
    95% CI(Reference)0.69–1.140.92–1.490.81–1.41
Nitrite plus nitrate, animal sources, median intake*2.22.23.73.7
Dietary vitamin C, median intake*1165311653
    No. of cases173132135145
    Multivariate HR1.000.820.900.830.50
    95% CI(Reference)0.65–1.030.72–1.130.66–1.03
Nitrite plus nitrate, processed meat sources, median intake*0.250.250.870.87
Dietary vitamin C, median intake*1165311653
    No. of cases182114126163
    Multivariate HR1.000.890.930.790.80
    95% CI(Reference)0.70–1.130.74–1.170.64–0.99

NOTE: Low/high distinctions were based on median intake values.

  • *mg/1,000 kcal/d.

  • Adjusted for sex, age (continuous), race (non-Hispanic white, non-Hispanic black, other, and missing), energy intake (continuous), education (<high school, high school graduate, post–high school other than college, some college, college graduate, postgraduate, and missing), height (eight prespecified categories and missing), and history of cancer at baseline (yes, no, and missing).