Table 1.
Age-standardized characteristics of study population (n = 14,553) according to categories of folate intake in 1991 in NHS II
| Total folate* |
Supplemental folate |
Food folate |
||||
|---|---|---|---|---|---|---|
| Q1 |
Q4 |
None |
≥600 μg/day |
Q1 |
Q4 |
|
| No. of participants | 3,600 | 3,413 | 6,791 | 1,161 | 3,418 | 3,601 |
| Folate intake, μg/day, median (range) | 246 (81‒294) | 873 (698‒2,770) | 0 | 900 (600‒2,000) | 189 (46‒212) | 342 (302‒1,030) |
| Age, years | 31.8 ± 3.2 | 31.9 ± 3.3 | 31.9 ± 3.3 | 31.8 ± 3.2 | 31.3 ± 3.1 | 32.4 ± 3.3 |
| White, % | 90.8 | 94.1 | 92.4 | 93.7 | 91.0 | 93.6 |
| Family history of diabetes, % | 11.7 | 10.8 | 11.3 | 9.9 | 11.2 | 11.0 |
| Nulliparous, % | 35.2 | 32.5 | 36.6 | 15.1 | 32.0 | 43.9 |
| Current smoking, % | 12.5 | 6.9 | 10.6 | 5.4 | 11.3 | 9.2 |
| Alcohol, g/day | 3.2 ± 5.6 | 2.5 ± 4.4 | 3.2 ± 5.2 | 2.1 ± 4.2 | 2.6 ± 5.1 | 3.4 ± 5.1 |
| BMI, kg/m2 | 23.6 ± 4.8 | 23.1 ± 4.0 | 23.4 ± 4.4 | 23.5 ± 4.3 | 23.6 ± 4.8 | 22.9 ± 3.9 |
| Physical activity, MET h/week | 19.0 ± 26.2 | 26.7 ± 33.5 | 22.6 ± 29.2 | 24.4 ± 34.1 | 17.8 ± 24.3 | 30.9 ± 35.5 |
| AHEI score | 39.2 ± 9.3 | 45.9 ± 10.4 | 43.0 ± 10.4 | 43.5 ± 10.7 | 37.3 ± 8.9 | 49.8 ± 10.0 |
| Total calories, kcal/day | 1,753 ± 554 | 1,762 ± 536 | 1,780 ± 545 | 2,029 ± 556 | 1,801 ± 570 | 1,804 ± 552 |
| Carbohydrate, %E | 48.1 ± 7.5 | 52.0 ± 7.1 | 49.9 ± 7.4 | 52.0 ± 6.6 | 49.1 ± 7.9 | 53.0 ± 7.2 |
| Glycemic load† | 120 ± 22 | 126 ± 21 | 122 ± 21 | 125 ± 19 | 123 ± 24 | 127 ± 21 |
| Glycemic index† | 54.8 ± 3.4 | 53.6 ± 3.2 | 54.2 ± 3.3 | 53.7 ± 3.0 | 55.4 ± 3.3 | 52.8 ± 3.1 |
| Protein, %E | 18.8 ± 3.4 | 19.6 ± 3.4 | 19.2 ± 3.4 | 19.5 ± 3.2 | 18.3 ± 3.5 | 19.6 ± 3.5 |
| Total fat, %E | 33.4 ± 5.5 | 29.5 ± 5.3 | 31.5 ± 5.6 | 29.9 ± 5.2 | 33.2 ± 5.8 | 28.3 ± 5.1 |
| Saturated fat, %E | 12.1 ± 2.4 | 10.7 ± 2.3 | 11.3 ± 2.4 | 11.0 ± 2.2 | 12.2 ± 2.6 | 10.0 ± 2.2 |
| Monounsaturated fat, %E | 12.8 ± 2.3 | 11.0 ± 2.3 | 11.9 ± 2.4 | 11.2 ± 2.2 | 12.7 ± 2.5 | 10.5 ± 2.2 |
| Polyunsaturated fat, %E | 5.6 ± 1.3 | 5.3 ± 1.3 | 5.5 ± 1.3 | 5.2 ± 1.4 | 5.5 ± 1.4 | 5.4 ± 1.3 |
| Trans fat, %E | 1.9 ± 0.7 | 1.4 ± 0.5 | 1.6 ± 0.6 | 1.5 ± 0.5 | 1.9 ± 0.7 | 1.3 ± 0.5 |
| Cholesterol, mg/day† | 245 ± 62 | 233 ± 67 | 239 ± 65 | 236 ± 64 | 236 ± 61 | 232 ± 74 |
| Total fiber, g/day† | 15.1 ± 3.6 | 19.4 ± 6.2 | 17.8 ± 5.3 | 18.4 ± 5.3 | 14.5 ± 4.4 | 22.0 ± 6.0 |
| Heme iron, mg/day† | 1.2 ± 0.4 | 1.0 ± 0.4 | 1.1 ± 0.4 | 1.0 ± 0.4 | 1.1 ± 0.4 | 1.0 ± 0.4 |
| Vitamin A, μg/day† | 798 ± 570 | 2,795 ± 1,423 | 1,043 ± 739 | 2,799 ± 1,531 | 1,310 ± 1,046 | 2,008 ± 1,381 |
| Vitamin C, mg/day† | 136 ± 173 | 382 ± 382 | 166 ± 189 | 349 ± 320 | 176 ± 235 | 334 ± 326 |
| Vitamin E, mg/day† | 11.3 ± 33.1 | 33.4 ± 61.7 | 12.7 ± 36.3 | 30.7 ± 60.1 | 15.6 ± 33.9 | 25.9 ± 57.5 |
| Total folate (B9), μg/day† | 240 ± 40 | 966 ± 315 | 313 ± 106 | 1215 ± 301 | 415 ± 308 | 624 ± 315 |
| Food folate, μg/day† | 216 ± 40 | 288 ± 79 | 260 ± 71 | 271 ± 69 | 186 ± 25 | 358 ± 59 |
| Supplemental folate, μg/day | 3.4 ± 16 | 570 ± 316 | 0 ± 0 | 914 ± 198 | 168 ± 274 | 209 ± 289 |
| Thiamin (B1), mg/day† | 1.7 ± 2.0 | 5.5 ± 10.0 | 1.9 ± 2.2 | 5.4 ± 10.0 | 2.8 ± 5.8 | 3.8 ± 7.1 |
| Riboflavin (B2), mg/day† | 2.0 ± 1.9 | 6.3 ± 10.0 | 2.2 ± 2.1 | 6.3 ± 9.9 | 3.2 ± 4.7 | 4.3 ± 7.1 |
| Niacin (B3), mg/day† | 23.6 ± 12.8 | 50.9 ± 26.6 | 25.6 ± 13.8 | 49.5 ± 26.9 | 31.6 ± 19.5 | 38.4 ± 25.2 |
| Pantothenic acid (B5), mg/day† | 5.0 ± 4.0 | 15.7 ± 15.0 | 5.6 ± 4.4 | 13.3 ± 17.6 | 8.3 ± 13.3 | 11.4 ± 12.7 |
| Vitamin B6, mg/day† | 3.4 ± 13.4 | 12.1 ± 25.4 | 3.7 ± 13.8 | 14.9 ± 26.4 | 5.2 ± 14.9 | 8.6 ± 23.7 |
| Cobalamin (B12), μg/day† | 5.9 ± 3.7 | 16.1 ± 16.8 | 6.7 ± 4.9 | 18.0 ± 23.4 | 8.5 ± 7.0 | 11.2 ± 14.2 |
| Multivitamin, % | 7.9 | 90.8 | 2.7 | 95.4 | 42.9 | 52.3 |
| Frequency of multivitamin intake, days/week | 0.2 ± 0.9 | 6.4 ± 2.5 | 0.1 ± 0.9 | 7.3 ± 1.9 | 2.3 ± 3.2 | 2.9 ± 3.4 |
| Vitamin B-complex, % | 1.3 | 5.7 | 1.5 | 4.7 | 2.3 | 5.4 |
| Folic acid, % | 0.0 | 2.1 | 0.0 | 4.6 | 0.3 | 0.9 |
Values are means ± SD for continuous variables and percentages for categorical variables. All values except age are standardized to the age distribution of the study population. Comparisons of all characteristics across quartiles of folate intake are significant, except for family history of diabetes. Q, quartile; %E, % of energy.
*Includes food folate and folic acid from supplements and fortified food.
†Energy adjusted using residual method.