Table 1.

Baseline characteristics of the Nurses' Health Study and Health Professional Follow-up cohort

Energy-adjusted folate intake, μg/d
n = 20,907n = 28,882n = 12,997n = 25,905n = 1,512N = 10,122n = 13,425n = 22,312
Dietary intake*
    Folate (μg/d)159246341677173258347682
    Vitamin B6 (mg/d)1.592.052.765.153.293.734.8013.6
    Vitamin B12 (mg/d)5.556.457.7815.17.898.799.7816.4
    Alcohol (g/d)
    Methionine (mg/d)1.741.861.951.932.
    Calcium (mg/d)574710797796577743858987
    Beef, pork, or lamb as a main dish (servings/wk)
Other characteristics
Median age (y)46.646.846.846.654.454.454.454.4
Former or current smoker (%)6056545560555150
    Pack-yr 23.320.418.719.231.727.224.123.1
Regular aspirin user3132323526272832
Body mass index (kg/m2) 24.424.524.324.025.825.925.625.3
Physical activity, METS/wk (%)§11.113.815.815.612.917.020.523.7
Postmenopausal (%)44444444
    Never used hormones (%)64626159
    Past use of hormones (%)18191919
    Current use of hormones (%)18192022
Current multivitamin use (%)813248412152367
Prior lower endoscopy (%)222222242627
Colorectal cancer in a parent or sibling (%)88789889
  • NOTE: Dietary intake and other characteristics at baseline questionnaire in 1980 (Nurses' Health Study) and 1986 (Health Professionals Follow-up Study). Mean value, unless otherwise indicated. All values have been directly standardized according to the age distribution of the cohort.

  • * Nutrient values (folate, vitamin B6, B12, methionine, and calcium) represent the mean of energy-adjusted intake.

  • Pack-years were calculated for former and current smokers only.

  • The body mass index is the weight in kilograms divided by the square of the height in meters.

  • § METS are metabolic equivalents. This was calculated based on the frequency of a range of physical activities (such as jogging) in 1986.

  • Hormones are defined as postmenopausal estrogen or estrogen/progesterone preparations. Percent of never, past, and current use was calculated among postmenopausal women only.