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