Table 1.
Characteristics of prospective cohort studies included in the meta-analysis of whole grain intake and type 2 diabetes in adults
| Author, year | Cohort | Follow time, follow-year, sex, country | Study size, age, cases | Dietary assessment method | Method of reporting whole grain intakes (unit) | Low whole grain intake, high whole grain intake | RR (95%CI) for highest dose group compared with lowest dose group | adjustments for confounders |
|---|---|---|---|---|---|---|---|---|
| Li et al., 2022 [34] | Women’s Health Initiative Observational Study | 1993/1998–2020, 15.8, F, USA | 108,681 w, mean age 63 years at baseline: 15,842 cases | validated FFQ, 122 food items | ingredient (g/day) | 6.3 g/day, 78.5 g/day | 0.84(0.79, 0.88) | Age, residence, energy intake, race/ethnicity, physical activity, smoking status, pack-years of cigarettes, alcohol, HRT, education, income, family history of diabetes, antihypertensive medication use, dietary protein sources, BMI |
| Hu et al., 2020a [33] | Nurses’ health study | 1976–2014, 40, F, USA | 69,139 w, 30–55 years: 8170 cases | validated FFQ, 116 items | ingredient (servings/day) | 0.1 servings/day, 1.9 servings/day | 0.68(0.63, 0.73) | Age, ethnicity, smoking, alcohol, multivitamin use, physical activity, modified alternative healthy eating index, family history of diabetes, HRT, oral contraceptive use, BMI |
| Hu et al., 2020b [33] | Nurses’ Health study II | 1989–2017, 28, F, USA | 89,120 w, 25–42 years: 7072 cases | validated FFQ, 116 items | ingredient (servings/day) | 0.3 servings/day, 2.5 servings/day | 0.73(0.68, 0.8) | Age, ethnicity, smoking, alcohol, multivitamin use, physical activity, modified alternative healthy eating index, family history of diabetes, HRT, oral contraceptive use, BMI |
| Hu et al., 2020c [33] | Health Professionals Follow-up study | 1986–2016, 30, M, USA | 36,525 m, 40–75 years: 3387 cases | validated FFQ, 116 items | ingredient (servings/day) | 0.2 servings/day, 2.8 servings/day | 0.72(0.64, 0.81) | Age, ethnicity, smoking, multivitamin use, physical activity, modified alternative healthy eating index, family history of diabetes, BMI |
| Kyro et al., 2018 [32] | Danish Diet, Cancer, and Health cohort | 1993/1997–2018,15, M&F, Denmark | 26,251 m & 29,214 w, 50–65 years: 7417 | validated FFQ, 192 food items | ingredient (g/day) | M: 19.45 g/day, 68.85 g/day; F: 19.05 g/day, 59.1 g/day | M: 0.8(0.73, 0.88); F: 0.85(0.77, 0.94) | Age, education, physical activity, smoking, alcohol, red processed meat, menopause, HRT, BMI |
| Wirstrom et al., 2013 [31] | Swedish middle-aged men and women | 1992/1998–2013, 8–10, M&F, Sweden | 5477 m/w, 35–56 years: 165 cases | validated FFQ, NA | ingredient (g/day) | 16.35 g/day, 73.35 g/day | 0.71(0.48, 1.04) | Age, sex, parental history of diabetes, BMI, physical activity, smoking, education, blood pressure |
| Ericson et al., 2013 [30] | Malmo Diet and Cancer Cohort | 1991/1996–2006, 12, M&F, Sweden | 27,140 m/w, 45–74 years: 1709 cases | validated diet history, FFQ, 168 food items | products (servings/day) | M: 1 servings/day, 2 servings/day; F: 0.01 servings/day, 2.3 servings/day | M: 0.83(0.67, 1.03); F: 0.85(0.68, 1.06) | Age, dietary method, season, total energy, education, smoking, alcohol, physical activity, BMI |
| van Dam et al., 2006 [29] | Black Women’s Health Study | 1995–2003, 8, F, USA | 41,186 w, age 21–69 years: 1964 cases | validated FFQ, 68 food items | products (serving/day) | 0.03 servings/day, 1.29 servings/day | 0.69(0.6, 0.79) | Age, total energy intake, BMI, smoking, physical activity, alcohol, parental history of diabetes, education, coffee, sugar sweetened soft drink, processed meat, red meat, low-fat dairy |
| Montonen et al., 2003 [28] | Finnish Mobile Clinic Health Examination Survey | 1966/1972–1995, 23, M&F, Finland | 2268 m &2030 w, 40–69 years: 52/102 cases | baseline FFQ, > 100 food items | products (g/day) | 79 g/day, 302 g/day | 0.65(0.36, 1.18) | Age, sex, geographic area, smoking, BMI, total energy intake, fruit, berries and vegetables |
| Mayer et al., 2000 [27] | Iowa Women’s Health Study | 1986–1992, 6, F, USA | 35,988 w, 55–69 years: 1141 cases | validated FFQ, 127 food items | products (servings/week) | 1 servings/week, 20.5 servings/week | 0.79(0.65, 0.96) | Age, total energy intake, BMI, WHR, education, smoking, alcohol, physical activity |
aBMI, body mass index; F&w, female; FFQ, food frequency questionnaire; HRT, hormone replacement therapy; M&m, male; WHR, waist-to-hip ratio