Table 1. Characteristics of included prospective cohort studies in the meta-analysis of dietary fish and n-3 polyunsaturated fatty acid intake and type 2 diabetes.
| Study source | Duration of follow-up (years) | Age (y) | No. of cases/size of cohort | Fish or n-3 PUFA type | Exposure range (g/d) | Adjusted RR (95% CI) | Adjusted variables |
| Meyer et al, 2001 (3) | 11 | 55–69 | 1890/35988 | LC n-3 PUFA | Highest: 0.39; ref: 0.03 | 1.11 (0.94, 1.30) | Age, total energy, WHR, BMI, physical activity, cigarette smoking, alcohol consumption, education, marital status, residential area, hormone replacement therapy, energy-adjusted dietary magnesium and cereal fiber, dietary protein, saturated fatty acids, polyunsaturated fatty acids, monounsaturated fatty acids, trans fatty acids and cholesterol. |
| van Dam et al, 2002 (29) | 12 | 40–75 | 1321/42504 | C18∶3n-3 | Highest: 0.671; ref: 0.321 | 0.93 (0.78, 1.11) | Age, total energy intake, time period, physical activity, cigarette smoking, alcohol consumption, hypercholesterolemia, hypertension, family history of type 2 diabetes, intake of cereal fiber and magnesium and BMI |
| Hodge et al, 2007 (5) | 4 | 36–72 | 364/3737 | C22∶6n-3 | Highest: Q5; ref: Q1 | 0.77 (0.52, 1.16) | Age, sex, country of birth, family history of diabetes, physical activity, alcohol intake, BMI, and waist-hip ratio |
| C20∶5n-3 | Highest: Q5; ref: Q1 | 0.68 (0.62, 1.34) | |||||
| C18∶3n-3 | Highest: Q5; ref: Q1 | 1.14 (0.75, 1.73) | |||||
| Kaushik et al_Nurses’ Health Study, 2009 (6) | 18 | 30–55 | 4159/61031 | LC n-3 PUFA | Highest: 0.49; ref: 0.06 | 1.23 (1.11, 1.37) | Smoking, alcohol consumption, physical activity, family history of diabetes mellitus, BMI, intakes of saturated fat, trans fats, linolenic acid, linoleic acid, caffeine, cereal fiber, glycemic index, calories, menopausal status, and postmenopausal hormone use |
| Fish | Highest: ≥5 times/wk; ref: <1 time/mo | 1.29 (1.05, 1.57) | |||||
| Kaushik et al_Nurses’ Health Study 2, 2009 (6) | 14 | 26–46 | 2728/91669 | LC n-3 PUFA | Highest: 0.36; ref: 0.06 | 1.25 (1.10, 1.42) | Smoking, alcohol consumption, physical activity, family history of diabetes mellitus, BMI, intakes of saturated fat, trans fats, linolenic acid, linoleic acid, caffeine, cereal fiber, glycemic index, calories, use of hormone replacement therapy and oral contraceptive use |
| Fish | Highest: ≥5 times/wk; ref: <1 time/mo | 1.32 (0.99, 1.74) | |||||
| Kaushik et al_Health Professionals Follow-up Study, 2009 (6) | 18 | 39–78 | 2493/42504 | LC n-3 PUFA | Highest: 0.62; ref: 0.09 | 1.12 (0.98, 1.28) | Smoking, alcohol consumption, physical activity, family history of diabetes mellitus, BMI, intakes of saturated fat, trans fats, linolenic acid, linoleic acid, caffeine, cereal fiber, glycemic index, and calories |
| Fish | Highest: ≥5 times/wk; ref: <1 time/mo | 1.16 (0.96, 1.41) | |||||
| van Woudenbergh et al, 2009 (7) | 15 | ≥55 | 463/4472 | C22∶6n-3+ C20∶5n-3 | Highest: 0.2368; ref: 0.0238 | 1.05 (0.80, 1.38) | Age, sex, smoking, education level, intake of energy, alcohol, trans fatty acid, fiber, intake of selenium, vitamin D and cholesterol |
| Total fish | Highest: 35.6; ref: 0 | 1.32 (1.02, 1.70) | Age sex, smoking, education level, intake of energy, alcohol, trans fatty acid, and fiber | ||||
| Fatty fish | Highest: ≥15.7; ref: 0 | 0.99 (0.71, 1.38) | Age sex, smoking, education level, intake of energy, alcohol, trans fatty acid, fiber and lean fish | ||||
| Lean fish | Highest: 30.6; ref: 0 | 1.30 (1.01, 1.68) | Age sex, smoking, education level, intake of energy, alcohol, trans fatty acid, fiber and fatty fish | ||||
| Patel et al, 2009 (14) | 10.2 | 40–79 | 725/21984 | Total fish | Highest: ≥1 portion/wk; ref: <1 portion/wk | 0.75 (0.58, 0.96) | Age, sex, family history of diabetes, smoking, education level, physical activity, total energy intake, alcohol intake, plasma vitamin C, BMI, and waist circumference |
| Oily fish | Highest: ≥1 portion/wk; ref: <1 portion/wk | 0.94 (0.78, 1.13) | |||||
| White fish | Highest: ≥1 portion/wk; ref: <1 portion/wk | 0.87 (0.73, 1.03) | |||||
| Shellfish | Highest: ≥1 portion/wk; ref: <1 portion/wk | 1.36 (1.02, 1.81) | |||||
| Djousse et al_Women’s Health Study, 2011 (9) | 12.4 | ≥45 | 2370/36328 | Marine n-3 PUFA | Highest: 0.43; ref: 0.07 | 1.44 (1.25, 1.65) | Age, BMI, parental history of diabetes, smoking, exercise, alcohol intake, menopausal status, red-meat intake, and quintiles of energy intake, linoleic acid, α-linolenic acid, dietary magnesium, trans fat, saturated fat, cereal fiber, and glycemic index |
| C18∶3n-3 | Highest: 1.59; ref: 0.79 | 1.01 (0.85, 1.21) | |||||
| Fish | Highest: 3.93 servings/wk; ref: 0.47 servings/wk | 1.49 (1.30, 1.70) | |||||
| Djousse et al_Cardiovascular Health Study, 2011 (8) | 10.6 | ≥65 | 204/3088 | C22∶6n-3+ C20∶5n-3 | Highest: >0.56; ref: ≤0.17 | 1.04 (0.67, 1.60) | Age, race, sex, clinic site, BMI, alcohol consumption, physical activity, current smoking, LDL cholesterol, and linoleic acid |
| C18∶3n-3 | Highest: >0.18; ref: ≤0.11 | 0.50 (0.24, 1.05) | |||||
| Fish | Highest: ≥5/wk; ref: <1/mo | 1.07 (0.35, 3.30) | Age, race, sex, clinic site, BMI, alcohol consumption, physical activity, current smoking, total energy intake and LDL cholesterol | ||||
| Nanri et al_men, 2011 (15) | 5 | 45–75 | 572/22921 | Oily fish | Highest: 71.2; ref: 10.7 | 0.79 (0.59, 1.05) | Age, study area, BMI, smoking status, alcohol consumption, family history of diabetes mellitus, total physical activity, history of hypertension, total energy intake, coffee consumption, intake of calcium, magnesium, dietary fiber, vegetable, fruit, meat, and rice |
| Lean fish | Highest: 30; ref: 3.3 | 1.05 (0.80, 1.38) | |||||
| Nanri et al_women, 2011 (15) | 5 | 45–75 | 399/29759 | Oily fish | Highest: 68.1; ref: 10.7 | 0.93 (0.67, 1.29) | The same as above |
| Lean fish | Highest: 23.3; ref: 2.7 | 1.02 (0.75, 1.40) | |||||
| Villegas et al_men, 2011 (10) | 4.1 | 40–74 | 900/51963 | LC n-3 PUFA | Highest: 0.2; ref: 0.02 | 0.89 (0.70, 1.12) | Age, energy intake, waist-to-hip ratio, BMI, smoking, alcohol consumption, physical activity, income level, educational level, occupation, family history of diabetes, hypertension and dietary pattern |
| Fish | Highest: 79; ref: 9.7 | 0.94 (0.74, 1.17) | |||||
| shellfish | Highest: 24.3; ref: 1.6 | 0.82 (0.65, 1.02) | |||||
| Villegas et al_women, 2011 (10) | 8.9 | 40–70 | 3034/64193 | LC n-3 PUFA | Highest: 0.2; ref: 0.02 | 0.84 (0.74, 0.95) | The same as above |
| Fish | Highest: 80.2; ref: 9.5 | 0.89 (0.78, 1.01) | |||||
| shellfish | Highest: 23.5; ref: 1.4 | 0.86 (0.76, 0.99) | |||||
| Brostow et al, 2011 (11) | 5.7 | 45–74 | 2252/43176 | C22∶6n-3+ C20∶5n-3 | Highest: 0.6; ref: 0.11 | 0.93 (0.77, 1.11) | Age, sex, dialect, year of interview, educational level, BMI, physical activity, smoking status, alcohol use, hypertension, intakes of omega-6, alternate omega-3, monounsaturated fat, saturated fat, dietary fiber, protein, and total energy |
| C18∶3n-3 | Highest: 1.06; ref: 0.27 | 0.79 (0.67, 0.93) | |||||
| Kroger et al, 2011 (27) | 7 | 35–65 | 673/2724 | LC n-3 PUFA | Highest: 0.59; ref: 0.04 (% of total fat intake) | 1.29 (0.95, 1.75) | Age, sex, BMI, waist circumference, cycling, sports activity, education, smoking status, alcohol intake, occupational activity, coffee intake, fiber intake, total fat intake and energy intake |
| C18∶3n-3 | Highest: 2.6; ref: 1.4 (% of total fat intake) | 1.13 (0.80, 1.59) |
Abbreviations: Q: quintile; ref: reference; LC n-3 PUFA: long-chain n-3 polyunsaturated fatty acids (C22∶6n–3+ C20∶5n-3).