Table 2.
Prospective studies evaluating polyphenol intake on the risk of type 2 diabetes.
| First author, publication year, study name, location | Sex | Follow-up (years) | Age at baseline (years) (mean) | Number of cases/participants | Exposure assessment and case ascertainment | Types of polyphenols analyzed | Relative risk (95% CI) (highest versus lowest category) | Adjustment for covariates |
|---|---|---|---|---|---|---|---|---|
| Knekt 2002, The FMCHES, Finland | Both | 18 | 39.3 ± 15.8 | 526/9878 | FFQ > 100 items/identified from Social Insurance Institution Finland | Quartiles of dietary intake of major flavonoid subclasses (total flavonoid intake 24.2 mg/d) | Q4 versus Q1 0.98 (0.78, 1.24) | Sex and age |
| Song 2005, WHS, United States | F | 8.8 | ≥45 (53) | 1614/38,018 | 131-item semiquantitative validated FFQ/self-report and confirmed with supplementary questionnaire about symptoms, American Diabetes Criteria | mg/d quintiles of dietary intake of total or individual flavonols and flavones and flavonoid-rich foods | Q5 versus Q1 (median intake mg/d: 47.2 versus 8.85) of total flavonoids 0.92 (0.78, 1.09) | Age, BMI, energy, total fat, smoking, exercise, alcohol use, history of hypertension, high cholesterol, family history of diabetes, fiber intake, glycemic load, magnesium |
| Nettleton 2006, Iowa Women's Health Study, United States | F | 18 | 55–69 (61) | 3395/35,816 | Validated 127-item FFQ/self-reported were determined by the following question: “Were you diagnosed for the first time by a doctor as having sugar diabetes?” | mg/d quintiles of flavonoid and flavonoid sources | Q5 versus Q1 (median intake mg/d: 680.4 versus 90.4) of total flavonoids 0.97 (0.86, 1.10) | Age, energy, education level, BMI, waist:hip ratio, activity level, smoking status, multivitamin use, and hormone therapy |
| Kataja-Tuomola 2011, ATBC, Finland | M | 10.2 | 50–69 (57.5) | 660/25,505 | Validated FFQ 275 food items/self-reported or medical diagnosis and Social Insurance Institution Finland | Quintiles of flavonols and flavones | Nonsignificant associations for kaempferol, luteolin, myricetin, quercetin | Age, supplementation, BMI, cigarettes smoked daily, smoking years, blood pressure, total cholesterol, high-density lipoprotein cholesterol, leisure-time physical activity, and daily intake of alcohol and energy |
| Wedick 2012, NHS, NHSII, HPFS, United States | F (NHS) | 24 | 30–55 (50) | 6878/70,359 | 131-item semiquantitative validated FFQ/self-report and confirmed with supplementary questionnaire about symptoms, the National Diabetes Group criteria | mg/d quintiles of dietary intake of major flavonoid subclasses | Q5 versus Q1 (median intake mg/d: 718.1 versus 105.2) of total flavonoids 0.85 (0.79, 0.92) | Age, BMI, smoking status, alcohol intake, multivitamin use, physical activity, family history of diabetes, postmenopausal status and hormone use, ethnicity, total energy, intakes of red meat, fish, whole grains, coffee, high-calorie sodas, and trans fat |
| F (NHSII) | 16 | 25–42 (36) | 3084/89,201 | Same as above | mg/d quintiles of dietary intake of major flavonoid subclasses | Q5 versus Q1 (median intake mg/d: 770.3 versus 112.1) of total flavonoids 0.99 (0.89, 1.11) | Same as above plus oral contraceptive use | |
| M (HPFS) | 20 | 40–75 (53) | 2649/41,334 | Same as above | mg/d quintiles of dietary intake of major flavonoid subclasses | Q5 versus Q1 (median intake mg/d: 624.3 versus 112.5) of total flavonoids 0.92 (0.81, 0.94) | Same as above except postmenopausal status and hormone use and oral contraceptive use | |
| Zamora-Ros 2013, Epic-InterAct, 8 European countries | Both | 3.99 million person-years of follow-up | 52.4 (9.1) | 12,403/16,154 | Country-specific FFQ/self-report and linkage to primary and secondary care registers, hospital and mortality data | mg/d quintiles of dietary flavonoids, types of flavonoids and lignans intake | Q5 versus Q1 (median intake mg/d: 817.5 versus 126.8) of total flavonoids 0.90 (0.77, 1.04) | Age, sex, and total energy intake, educational level, physical activity, smoking status, BMI, alcohol intake, intakes of red meat, processed meat, sugar-sweetened soft drinks, and coffee, intakes of fiber, vitamin C, and magnesium |
| Jacques 2013, Framingham Offspring Cohort, United States | Both | 11.9 | 54.2 (53.8, 54.5) | 308/2915 | Validated FFQ/fasting glucose concentrations and/or a medical and medication use history obtained by a physician at each study examination | 6 flavonoid classes and total flavonoids | HR per 2.5-fold difference in flavonoid intake (cumulative mean flavonoid intake) 0.89 (0.75, 1.05) | Sex, age, cardiovascular disease, current smoker (y/n), BMI, and cumulative mean energy intake, vegetable and fruit intake |
| Zamora-Ros 2014, EPIC-InterAct, United States | Both | 3.99 million person-years of follow-up | 52.4 (9.1) | 12,403/16,154 | Country-specific FFQ/self-report and linkage to primary and secondary care registers, hospital and mortality data | mg/d quintiles of dietary flavanol and flavonol intake | Q5 versus Q1 of sum of flavanols and flavonols (median intake in mg/d: 713.6 versus 97.6). Inverse associations between all flavan-3-ol monomers, proanthocyanidin dimers and trimers (Q5 versus Q1 0.81 (0.71, 0.92) and 0.91 (0.80, 1.04), resp.) | Age, sex, and total energy intake, educational level, physical activity, smoking status, BMI, alcohol intake, intakes of red meat, processed meat, sugar-sweetened soft drinks, and coffee, intakes of fiber, vitamin C, and magnesium |
| Tresserra-Rimbau 2016, PREDIMED, Spain | Both | 5.51 | 55–80 | 314/3430 | Validated 137-item FFQ/fasting plasma glucose ≥7 mmol/L or 2 h plasma glucose ≥11.1 mmol/L after a 75 g oral glucose load, confirmed by a second test using the same criteria, the American Diabetes Association criteria | Total polyphenols, flavonoids, stilbenes, lignans | T3 versus T1 (mean intake 1002 versus 600) of total polyphenols 0.72 (0.52, 0.99) | Age, sex, recruitment center, intervention group. Smoking, BMI, physical activity, dyslipidemia, hypertension, education level, total energy intake, alcohol intake, adherence to the Mediterranean diet, and fasting glucose |
| Ding 2016, NHS, NHS2, HPFS, United States | F (NHS) | 8 | 30–55 (50) | 3671/63,115 | 131-item semiquantitative validated FFQ/self-report and confirmed with supplementary questionnaire about symptoms, the National Diabetes Group criteria | mg/d quintiles of isoflavone consumption | Q5 versus Q1 (median intake mg/d: 2.78 versus 0.17) of isoflavones 0.97 (0.88, 1.07) | Age, race, family history of T2D, baseline disease status, BMI, physical activity, overall dietary pattern (alternate Healthy Eating Index score, in quintiles), total energy intake and smoking status and menopausal status, postmenopausal hormone use |
| F (NHSII) | 8 | 25–42 (36) | 3920/79,061 | Same as above | mg/d quintiles of isoflavone consumption | Q5 versus Q1 (median intake mg/d: 5.73 versus 0.17) of isoflavones 0.85 (0.76, 0.95) | Same as above | |
| M (HPFS) | 8 | 40–75 (53) | 742/21,281 | Same as above | mg/d quintiles of isoflavone consumption | Q5 versus Q1 (median intake mg/d: 5.09 versus 0.31) of isoflavones 0.80 (0.62, 1.02) | Same as above except postmenopausal status and hormone use |
ATBC, α-Tocopherol, β-Carotene Cancer Prevention Study; WHS, Women's Health Study; FFQ, food frequency questionnaire; NHS, Nurses' Health Study; HPFS, Health Professionals Follow-up Study; PREDIMED, Prevención con Dieta Mediterránea; EPIC, The European Prospective Investigation into Cancer and Nutrition; FMCHES, Finnish Mobile Clinic Health Examination Survey.