Table 1.

Age-standardized baseline characteristics of study participants in relation to total energy intake

CharacteristicQuartile of energy intake
Q1 (n = 6,885)Q2 (n = 6,885)Q3 (n = 6,886)Q4 (n = 6,885)
Range of energy intake (kcal/d)<1,3161,316-1,6561,657-2,083≥2,084
Age (y)*63.1 ± 5.363.0 ± 5.463.0 ± 5.462.5 ± 5.3
BMI (kg/m2)*26.5 ± 5.126.7 ± 5.227.0 ± 5.427.8 ± 5.8
Height (m)*1.63 ± 0.071.63 ± 0.061.63 ± 0.071.64 ± 0.07
Recreational physical activity (%), h/wk
    Never17.714.314.215.0
    <119.818.218.317.9
    112.212.112.011.7
    216.116.917.716.7
    315.717.117.316.4
    ≥418.521.420.522.3
Family history of breast cancer (%)13.614.413.713.9
Mammography in past 3 y (%)
    Never8.87.78.29.7
    Once18.918.218.219.7
    More than once72.374.173.670.6
Age at menarche (%), y
    <1119.719.119.820.1
    12-1353.956.054.753.7
    14-1521.620.821.521.5
    ≥164.74.14.04.7
Age at first birth (%), y
    <1918.715.014.815.9
    20-2446.949.147.747.5
    25-2919.820.621.020.0
    ≥306.06.47.37.4
Parity (%)
    08.68.99.29.3
    17.06.67.27.4
    224.624.023.922.1
    326.225.725.024.6
    416.316.916.817.4
    ≥517.317.917.919.2
Age at menopause (%), y
    <4015.513.313.012.8
    40-4413.914.615.513.2
    45-4924.023.222.223.9
    50-5436.637.639.338.2
    ≥5510.011.312.011.9
Menopausal hormone therapy (%)
    Current user52.053.152.649.6
    Past user15.915.416.316.4
Dietary fat (g/d)*,49.1 ± 10.354.1 ± 10.654.8 ± 10.651.3 ± 11.1
Alcohol (g/d)*,4.91 ± 7.996.30 ± 10.467.11 ± 12.147.42 ± 14.81
  • NOTE: All values (except age) are directly standardized to the age distribution of the study population.

  • * Mean ± SD.

  • Any first-degree relative with breast cancer.

  • Adjusted for energy using regression analysis.