Table 1

Age and age-standardised baseline characteristics of the Nurses' Health Study and Health Professionals Follow-up cohort*

Energy-adjusted folate intake (μg/day)
N=20 907N=28 882N=12 997N=25 905N=1512N=10 121N=13 423N=22 307
Total intake**
Folate (μg/day)159246341677173258347682
Vitamin B6 (mg/day)1.592.052.765.153.293.734.8013.6
Vitamin B12 (mg/day)5.556.457.7815.17.898.799.7816.4
Alcohol (g/day)
Methionine (mg/day)1.741.861.951.932.
Calcium (mg/day)574710797796577743858987
Beef, pork or lamb as a main dish (servings/week)
Other characteristics*
Median age (years)46.646.846.846.654.454.454.454.4
Former or current smoker (%)6056545560555150
Regular aspirin user3132323526272832
Body mass index (kg/m2)24.424.524.324.025.825.925.625.3
Physical activity, METS/week (%)§11.113.815.815.612.917.020.523.7
Post-menopausal (%)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
  • * Dietary intake and other characteristics at baseline questionnaire in 1980 (NHS) and 1986 (HPFS). Mean value, unless otherwise indicated. All values have been directly standardised according to the age distribution of the cohort.

  • 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 metres.

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

  • Hormones are defined as post-menopausal oestrogen or oestrogen/progesterone preparations. Per cent of never, past and current use was calculated among post-menopausal women only.

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