Table 2.
Prospective studies of whole grain intake and incidence of colorectal cancer
| Study, country | Study name | Follow-up period | Study size, sex, age, No of cases* | Diet assessment, No of items | Exposure | Quantity | Relative risk (95% CI) | Adjustment for confounders |
|---|---|---|---|---|---|---|---|---|
| Fung 201039, USA | Nurses’ Health Study | 1980-2006, 26 years | 87 256 women, age 34-59, 1432 cases | Validated food frequency questionnaire, 61-116 food items | Whole grains | Per serving/day | 0.95 (0.89 to 1.02) | Age, body mass index, alcohol, family history of colorectal cancer, physical activity, aspirin, colonoscopy, history of polyps, pack years of smoking, energy, multivitamins |
| Fung 201039, USA | Health Professionals Follow-Up Study | 1986-2006, 20 years | 45 490 men, age 40-75, 1032 cases | Validated food frequency questionnaire, about 140 food items | Whole grains | Per serving/day | 0.94 (0.88 to 0.99) | Age, body mass index, alcohol, family history of colorectal cancer, physical activity, aspirin, colonoscopy, history of polyps, pack years of smoking, energy, multivitamins |
| Egeberg 201038, Denmark | The Diet Cancer and Health Cohort Study | 1993-2006, 10.2 years | 26 630 men and 29 189 women, age 50-64, 461 cases of colon cancer and 283 cases of rectal cancer | Validated food frequency questionnaire, 192 food items | Whole grains, colon cancer, men | >160 v ≤75 g/day | 0.61 (0.43 to 0.86) | Age, body mass index, alcohol intake, school education, red and processed meat, HRT (women), leisure time physical activity |
| Whole grains, rectal cancer, men | >160 v ≤75 g/day | 0.88 (0.57 to 1.36) | ||||||
| Whole grains, colon cancer, women | >160 v ≤75 g/day | 0.92 (0.63 to 1.35) | ||||||
| Whole grains, rectal cancer, women | >160 v ≤75 g/day | 0.81 (0.50 to 1.30) | ||||||
| Schatzkin 200727, USA | NIH-AARP Diet and Health Study | 1995-2000, 5 years | 291 988 men and 197 623 women, age 50-71, 2974 cases | Validated food frequency questionnaire, 124 food items | Whole grains | 1.3 v 0.2 serv/1000 kcal/day | 0.79 (0.70 to 0.89) | Age, sex, physical activity, smoking, HRT (women), red meat, dietary calcium, dietary folate, energy |
| McCarl 200625, USA | Iowa Women’s Health Study | 1986-2000, 14 years | 35 197 women, age 55-69, 954 cases | Validated food frequency questionnaire, 127 food items | Whole grains | ≥19 v ≤3.5 servings/week | 0.81 (0.66 to 0.99) | Age |
| Larsson 200535, Sweden | Swedish Mammography Cohort Study | 1987-2004, 14.8 years | 61 433 women, age 40-76, 805 cases | Validated food frequency questionnaire, 67 food items | Whole grain | ≥4.5 v <1.5 servings/day | 0.80 (0.60 to 1.06) | Age, body mass index, education, energy, saturated fat, calcium, red meat, fruits and vegetables |
| Wu 200437, USA | Health Professional’s Follow-up Study | 1986-2000, 14 years | 47 311 men, age 45-75, 561 cases of colon cancer | Validated food frequency questionnaire, 131 food items | Whole grain | Fifths: 5 v 1 | 0.75 (0.57 to 1.00) | Age, family history of colorectal cancer in first degree relative, history of endoscopy, physical activity, pack years of smoking before age 30, race, aspirin use, energy |
| McCullough 200336, USA | Cancer Prevention Study 2 | 1992-7, 4.5 years | 62 609 men and 70 554 women, age 50-74, 298/210 cases of colon cancer | Validated food frequency questionnaire, 68 items | Whole grains, men | ≥11.0 v. <2.0 servings/week | 0.95 (0.64 to 1.42) | Age, exercise metabolic equivalent of tasks, aspirin, smoking, family history of colorectal cancer, body mass index, education, energy, multivitamin use, total calcium, red meat intake, and HRT (women) |
| Whole grains, women | ≥11.2 v <2.5 servings/week | 1.17 (0.73 to 1.87) |
HRT=hormone replacement therapy.
*Cases refer to colorectal cancer unless specified otherwise.