Age and age-standardised baseline characteristics of the Nurses' Health Study and Health Professionals Follow-up cohort*
| Energy-adjusted folate intake (μg/day) | ||||||||
| Characteristic* | Women | Men | ||||||
| <200 | 200–299 | 300–399 | ≥400 | <200 | 200–299 | 300–399 | ≥400 | |
| N=20 907 | N=28 882 | N=12 997 | N=25 905 | N=1512 | N=10 121 | N=13 423 | N=22 307 | |
| Total intake** | ||||||||
| Folate (μg/day) | 159 | 246 | 341 | 677 | 173 | 258 | 347 | 682 |
| Vitamin B6 (mg/day) | 1.59 | 2.05 | 2.76 | 5.15 | 3.29 | 3.73 | 4.80 | 13.6 |
| Vitamin B12 (mg/day) | 5.55 | 6.45 | 7.78 | 15.1 | 7.89 | 8.79 | 9.78 | 16.4 |
| Alcohol (g/day) | 6.7 | 6.4 | 6.0 | 6.3 | 13.4 | 13.0 | 11.4 | 10.5 |
| Methionine (mg/day) | 1.74 | 1.86 | 1.95 | 1.93 | 2.03 | 2.13 | 2.20 | 2.21 |
| Calcium (mg/day) | 574 | 710 | 797 | 796 | 577 | 743 | 858 | 987 |
| Beef, pork or lamb as a main dish (servings/week) | 3.1 | 2.6 | 2.3 | 2.3 | 2.4 | 2.1 | 1.8 | 1.5 |
| Other characteristics* | ||||||||
| Median age (years) | 46.6 | 46.8 | 46.8 | 46.6 | 54.4 | 54.4 | 54.4 | 54.4 |
| Former or current smoker (%) | 60 | 56 | 54 | 55 | 60 | 55 | 51 | 50 |
| Pack-years† | 23.3 | 20.4 | 18.7 | 19.2 | 31.7 | 27.2 | 24.1 | 23.1 |
| Regular aspirin user | 31 | 32 | 32 | 35 | 26 | 27 | 28 | 32 |
| Body mass index (kg/m2)‡ | 24.4 | 24.5 | 24.3 | 24.0 | 25.8 | 25.9 | 25.6 | 25.3 |
| Physical activity, METS/week (%)§ | 11.1 | 13.8 | 15.8 | 15.6 | 12.9 | 17.0 | 20.5 | 23.7 |
| 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 | 12 | 15 | 23 | 67 |
| Prior lower endoscopy (%) | 2 | 2 | 2 | 2 | 22 | 24 | 26 | 27 |
| Colorectal cancer in a parent or sibling (%) | 8 | 8 | 7 | 8 | 9 | 8 | 8 | 9 |
↵* 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.