Table 1.

Baseline Characteristics of the Nurses' Health Study Cohort^*

		Energy-adjusted Folate Intake, μg/day
		<200	200-299	300-399	≥400
Characteristic*		N=20,907	N=28,882	N=12,997	N=25,905
Dietary intake ψ
	Folate (μg/day)	159	246	341	678
	Beef, pork, or lamb as a main dish (servings per week)	3.1	2.6	2.3	2.3
	Vitamin B6 (mg/day)	1.59	2.05	2.76	5.15
	Vitamin B12 (mg/day)	5.55	6.45	7.78	15.1
	Alcohol (g/day)	6.7	6.4	6.0	6.3
	Methionine (mg/day)	1.74	1.86	1.95	1.93
	Calcium (mg/day)	607	723	798	812
	Beef, pork, or lamb as a main dish (servings/week)	3.1	2.6	2.3	2.3
Other characteristics*
Median age (yr)		45.5	46.8	47.5	47.0
Former or current smoker (%)		60	56	54	55
	Pack-yr †	23.3	20.4	18.7	19.2
Regular aspirin user		31	32	32	35
Body mass index (kg/m2)‡		24.4	24.5	24.3	24.0
Physical activity, METS/wk (%) §		11.1	13.8	15.8	15.6
Post-menopausal (%) ¶		44	44	44	44
	Never used hormones (%)	64	62	61	59
	Past use of hormones (%)	18	19	19	19
	Current use of hormones (%)	18	19	20	22
Current multivitamin use (%)		8	13	24	84
Prior lower endoscopy (%)		2	2	2	2
Colorectal cancer in a parent or sibling (%)		8	8	7	8

^*Dietary intake and other characteristics at baseline questionnaire in 1980 (mean value, unless otherwise indicated). All values have been directly standardized 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 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 post-menopausal estrogen or estrogen/progesterone preparations. Percent of never, past, and current use was calculated among post-menopausal women only.

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