Table 4.
Characteristics of randomized controlled trials1
| Author (year) (reference) | Design | Country | Population | Outcome(s) | Intervention | Intervention dose | Control | Sample size (analysed) | Duration | Overall RoB | Funding |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Al Abdrabalnabi (2020) (103) | Parallel | USA & Spain | WAHA study; age 62–79 years; normotensive or mild hypertension, low CVD risk | Blood pressure, HDL-C, TG, glucose | Walnuts | 15 E% (i.e., 30, 45 or 60 g/day) | No walnuts. | I: 319 C: 306 |
2 years | Some concerns | Industry |
| Barbour (2015) (104) | Crossover | Australia | Healthy, overweight; mean age 65 years | Lipids, glucose, insulin sensitivity | Peanuts | 15–20 E% (i.e. 84 g/day for men, 56 g/day for women) | No nuts | 61 | 12 weeks | Some concerns | Mixed |
| Bashan & Bakman (2018) (105) | Parallel | Turkey | Adults with dyslipidaemia; mean age 41 years | Lipids | Walnuts + AHA dietary guidelines | ‘One handful’ (40–50 g) | AHA dietary guidelines | I: 73 C: 72 |
12 weeks | High | Agency |
| Casas-Agustench (2011) (106) | Parallel | Spain | Adults with metabolic syndrome, mean age 52 years | Lipids, glucose, insulin resistance | Walnuts, hazelnuts and almonds + prudent diet | 30 g/day | No nuts/peanuts + prudent diet | I: 25 C: 25 |
12 weeks | Some concerns | Mixed |
| Coates (2020) (107) | Parallel | Australia | Adults with overweight/obesity; 50–80 years | Blood pressure, lipids, glucose insulin resistance | Almonds | 15 E% 6 days/week | Carbohydrate-rich snack foods; no nuts | I: 63 C: 64 |
12 weeks | Low | Industry |
| Gulati (2014) (34) | Parallel | India | Adults with metabolic syndrome; mean age 42.5 years | Lipids, glucose, HbA1c | Pistachio nuts | 20 E% | Dietary guidelines | I: 30 C: 30 |
24 weeks | Some concerns | Industry |
| Hernandez-Alonso (2014) (108) | Crossover | Spain | Adults with prediabetes; age 25–65 years | Blood pressure, lipids, glucose, insulin resistance | Pistachio nuts + isocaloric individual diet | 2 oz (57 g)/day | Other fatty foods, mostly olive oil + isocaloric individualized diet | 54 | 16 weeks | Some concerns | Industry |
| Hunter (2021) (109) | Parallel | USA | Healthy adults; BMI ≥27 kg/m2; mean age 37 years | Lipids, glucose, HbA1c, insulin resistance | Almonds for breakfast and snack + avoid other nuts | 1.5 oz (42 g)/day | Habitual breakfast and snack | I: 69 C: 65 |
6 months | Low | Industry |
| Hwang (2019) (110) | Crossover | Korea | Adults with metabolic syndrome; mean age 39.4 years | Blood pressure, lipids, glucose, HbA1c | Walnuts | 45 g/day | White bread | 84 | 16 weeks | High | Industry |
| Kasliwal (2015) (111) | Parallel | India | Adults with dyslipidaemia | Blood pressure, lipids, gluose | Pistachio nuts + TLC diet | 40 g shelled | No nuts + TLC diet | I: 21 C: 21 |
12 weeks | High | NI |
| Liu (2018) (112) | Parallel | Korea | Young, healthy adults; age 20–39 years, BMI 17–30 kg/m | Blood pressure, lipids | Almonds, as snacks or pre-meal | 56 g/day | High-carbohydrate foods, isocaloric | I: 57 C: 28 |
20 weeks | High | Industry |
| Madan (2021) (113) | Parallel | India | Adolescents and young adults with metabolic dysfunction (i.e. prediabetes or insulin resistance); age 16–25 years | Lipids, glucose, insulin resistance | Almonds | 20 E%/56 g/day | Isocaloric Indian savory snacks | I: 107 C: 112 |
12 weeks | High | Industry |
| Njike (2015) (114) | Crossover | USA | Adults at high risk for diabetes (e.g. metabolic syndrome); mean age 54.9 years | Blood pressure, lipids, glucose, HbA1c | Walnuts with or without calorie-adjustment | 56 g/day | No walnuts | 97 | 6 months | Some concerns | Industry |
| Tey (2013) (115) | Parallel | New Zealand | Healthy, BMI ≥25 kg/m2, mean age 42.5 years | Blood pressure, lipids | Hazelnuts | 30 g and 60 g | Habitual diet, no nuts | I 30 g: 33 I 60 g: 37 C: 37 |
12 weeks | Some concerns | NI |
| Torabian (2010) (116) | Crossover | USA | Healthy adults with normal to moderately high serum cholesterol; mean age 54 years | Lipids | Walnuts | 12 E% (28–64 g/day) | Habitual diet | 87 | 6 months | Some concerns | Industry |
| Wang, D (2021) (117) | Parallel | China | Subjects with or at risk for metabolic syndrome; mean age 46.2 years | Blood pressure, lipids, glucose | Peanuts | 20 E%/56 g/day | White rice bars, isocaloric | I: 109 C: 100 |
12 weeks | Low | Mixed |
| Wang, J (2021) (118) | Parallel | USA | Healthy, BMI 27–35 kg/m; age 30–68 years. | Blood pressure, lipids | Mixed nuts (almonds, cashew nuts, hazelnuts, macadamia, pecan, pistachio, walnuts) | 1.5 oz/d | Pretzel snack | I: 56 C: 39 |
24 weeks (12 weeks hypo-caloric, 12 weeks eucaloric) | High | Industry |
| Wang, X (2012) (119) | Parallel | China | Subjects with metabolic syndrome; age 25–65 years | Blood pressure, lipids, glucose | Pistachio nuts + AHA Step I diet | Recommended serving: 42 g/day Higher serving: 70 g/day |
No pistachio nuts + AHA Step I diet | I 42 g: 27 I 70 g: 29 C: 30 |
12 weeks | Some concerns | Industry |
1
Abbreviations: AHA, American Heart Association; C, control group; HbA1c, glyacted haemoglobin; HDL-C, high-density lipoprotein cholesterol; I, intervention group; TLC, therapeutic lifestyle changes.