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. Author manuscript; available in PMC: 2014 Sep 1.
Published in final edited form as: Ann Epidemiol. 2013 May 29;23(9):558–563. doi: 10.1016/j.annepidem.2013.04.011

Table 1.

Baseline characteristic of participants according to folic acid fortification period in the NHS and HPFS*

Pre-fortification (1980/1986–1998)
Post-fortification (1998–2008)
Characteristic NHS (1980) HPFS (1986) NHS (1998) HPFS (1998)
No. 87,856 46,874 69,330 28,548
Age (years) 46.2 (7.2) 53.8 (9.7) 63.8 (7.1) 64.3 (9.0)
Height (inches) 64.5 (2.4) 70.1 (2.8) Same as pre-fortification
BMI (kg/m2) 24.3 (4.8) 25.5 (3.3) 26.7 (5.3) 26.1 (3.6)
Family history of colorectal cancer (%)** 8.0*** 13.7 15.0 14.0
Former or current postmenopausal hormone use (%) 18.5 NA 31.7 NA
Alcohol intake (g/d) 6.4 (10.5) 11.3 (15.4) 5.0 (9.1) 10.9 (14.0)
Non-alcohol drinkers (%) 32.1 23.7 20.3 23.5
Smoking status (%)
  Past 27.6 43.4 44.9 48.0
  Current 28.9 10.0 10.5 5.0
Red meat as main dish (servings/d) 0.4 (0.3) 0.3 (0.2) 0.1 (0.1) 0.2 (0.2)
Total calcium intake (mg/d) 732.5 (314.6) 897.1 (424.4) 1268 (597.6) 1023.7 (481.3)
One-carbon nutrient
  Total folate intake (mcg/d) 365.3 (275.0) 480.2 (276.2) 633.9 (271.7) 717.6 (327.5)
  Dietary folate intake (mcg/d) 258.0 (105.6) 356.5 (118.0) 392.0 (113.4) 463.2 (137.6)
  Supplemental folic acid intake (mcg/d) 156.1 (354.5) 180.3 (279.2) 353.3 (250.4) 384.8 (296.1)
  Total choline intake (mg/d) 360.1 (79.3) 399.8 (93.8) 298.8 (66.4) 375.7 (85.4)
  Total betaine intake (mg/d) 96.6 (51.0) 130.2 (59.7) 102.8 (43.7) 130.9 (53.2)
  Total vitamin B6 intake (mg/d) 3.0 (9.0) 8.6 (24.9) 14.9 (35.6) 15.3 (35.9)
  Total vitamin B12 intake (mcg/d) 8.9 (20.3) 12.6 (18.2) 21.2 (34.8) 24.4 (44.3)
  Total methionine intake (g/d) 1.9 (0.5) 2.2 (0.5) 1.6 (0.3) 2.0 (0.5)
*

Age-standardized values; mean (SD) or %; NHS, Nurses’ Health Study (NHS); HPFS, Health Professionals Follow-up Study

**

Family history of colorectal cancer was asked in 1982, 1988, 1992, and 1996.

***

Assessed in 1982