Table 1 Characteristics of the included studies
Author, year | Country | Study design | Study duration | Study population | Baseline characteristics | Intervention | Methods for measuring dietary adherence | Gut microbiota analysis method |
|---|---|---|---|---|---|---|---|---|
Ahrens et al., 2021 | US | Self-controlled trail | 6 days | N = 73; Individuals with moderate to high ASCVD risk | Age: 46.9 ± 12.4 years BMI: 31.1 ± 8.8 kg/m2 | Plant-based food with minimal sugar, salt, and oil | None | 16S rRNA V3-V4 hypervariable region sequencing |
Choo et al., 2023 | Australia | 2*2 cross-over RCT | 8 weeks per intervention, 8-week wash-out | N = 34; Adults with a risk of CVD: age between 45 and 75 years, an elevated SBP of 120 mmHg, and a diagnosis of at least two other risk factors | Age: 61.1 ± 6.9 years BMI: 30.5 ± 3.5 kg/m2 | Mediterranean diets supplemented with adequate dairy foods vs. low-fat control diets | Completed MedDiet adherence tool and low-fat diet adherence tool each fortnight; 3-day weighed food record | 16S rRNA V4 hypervariable region sequencing |
Clark et al., 2019 | US | Self-controlled trail | 9 weeks | N = 17; Individuals diagnosed with MetS who have at least 3 risk factors | Age: 22.2 ± 3.4 years BMI: 37.9 ± 5.0 kg/m2 | Diet comprising 50% fruit and vegetable intake | Participants provided daily food and activity logs, food receipts, and food pictures weekly | 16S rRNA V3-V4 hypervariable region sequencing |
Djekic et al., 2020 | Sweden | Crossover RCT | 4 weeks per intervention, 4-week wash-out | N = 31; Adults age > 18 years, with stable ischemic heart disease, who underwent percutaneous coronary intervention > 1 month before the study initiation, and received optimal medical therapy | Age: 67.0 (63.0–70.0) years BMI: 27.5 ± 2.9 kg/m2 | Lacto-ovo-vegetarian diet vs. meat diet | 3-day weighted food record | 16S rRNA V4 hypervariable region sequencing |
Eriksen et al., 2020 | Sweden | Crossover RCT | 8 weeks per intervention, 8-week wash-out | N = 49; Men aged 49–74 years, who had at least 2 MetS risk factors | Age: 65.0 ± 8.0 years BMI: 30.9 ± 3.3 kg/m2 | Whole grain rye diet with 4 weeks secoisolariciresinol diglucoside lignan capsules vs. whole grain wheat diet | Weighed 3-day dietary records and personal checklists | 16S rRNA V3-V4 hypervariable region sequencing |
Galie et al., 2021 | Spain | Crossover RCT | 8 weeks per intervention, 1 month wash-out | N = 50; Idividual aged 25–60 years with a BMI between 25 and 35 kg/m2 and diagnosed with MetS | Age: 51.4 (49.2–53.6) years | Mediterranean diet vs. a daily intake of 50 g of mixed nuts | 17-item MedDiet score, counting the empty nuts-packaging, 3-day dietary records | 16S rRNA V4 hypervariable region sequencing |
Guevara-Cruz et al., 2019 | Mexico | Parallel RCT | 75 days | N = 113; Adults aged 20–60 years, with a BMI 25–50 kg/m2, and meeting 3 positive criteria for MetS | Age: 40.8 ± 0.4 years; BMI: 33.8 ± 0.2 kg/m2 | Reduced-energy low-saturated-fat diet with functional foods | 24-h diet recall, 3-day food records, and measuring the number of empty packages returned | 16S rRNA V3-V4 hypervariable region sequencing |
Guo et al., 2021 | China | Parallel RCT | 8 weeks | N = 46; Adults aged 30–50 years, with central obesity and 2 other risk factors | Age: 40.2 ± 5.7 years; BMI: 28.0 (25.8–32.9) kg/m2 | Intermittent fasting (75% of energy restriction for 2 nonconsecutive days a week) | 3-day dietary records | 16S rRNA |
Hald et al., 2016 | Denmark | Crossover RCT | 4 weeks per intervention, 4-week wash-out | N = 22; Adults aged 39–75 years with MetS | Age: 60.0 (48.0–67.0) years; BMI: 30.6 (29.3–35.2) kg/m2 | Healthy-carbohydrate diet with high concentration of diet fibre vs. low-fibre Western-style diet | 3-day dietary records | 16S rRNA V4 hypervariable region sequencing |
Haro et al., 2016 | Spain | Parallel RCT | 2 years | N = 239; Patients diagnosed with coronary heart disease with or without MetS | Age: 61.4 ± 0.9 years in non-MetS group, 60.2 ± 0.7 years in MetS group | Mediterranean diet vs. low-fat high-carbohydrate diet (28% fat [12% monounsaturated, 8% polyunsaturated and 8% saturated]) | 14-item/9-point questionnaire | 16S rRNA |
Haro et al., 2016 | Spain | Parallel RCT | 1 year | N = 20; Men with obesity and coronary heart disease | Age: 63.3 ± 2.0 years BMI: 32.2 ± 0.5 kg/m2 | Mediterranean diet vs. low-fat high-complex carbohydrate diet (28% fat [12% monounsaturated, 8% polyunsaturated and 8% saturated]) | None | 16S rRNA |
Haro et al., 2017 | Spain | Parallel RCT | 2 years | N = 106; Male patients diagnosed with coronary heart disease; 33 obese people with MetS, 32 obese people without MetS, and 41 non obese people without MetS | Age: 59.0 ± 1.8, 63.7 ± 1.7, 61.7 ± 1.4 years; BMI: 32.4 ± 0.8, 32.9 ± 0.6, 27.1 ± 0.3 kg/m2 | Mediterranean diet vs. low-fat diet (< 30% total fat [< 10% saturated fat, 12–14 MUFA fat and 6–8% PUFA fat]) | 14-item/9-point questionnaire | 16S rRNA V4 hypervariable region sequencing |
Maifeld et al., 2021 | Germany | Parallel RCT | 3 months | N = 35; Patients with MetS | Age: 58.0 ± 8.0, and 62.0 ± 8.0 years; BMI: 34.0 ± 4.9, and 33.0 ± 4.7 kg/m2 | 7 days Fasting (calorie-restricted vegan diet) followed modified DASH diet vs. only modified DASH diet | None | 16S rRNA gene V4 region amplification, and shotgun metagenomic sequencing |
Muralidharan et al., 2021 | Spain | Parallel RCT | 1 year | N = 362; Adults aged 55–75 years, who are overweight/obese and have at least 3 components of MetS | Age: 64.3 ± 5.1, 65.1 ± 4.9 years BMI: 33.4 (30.8–36.0), 32.9 (30.5–35.6) kg/m2 | Energy-reduced Mediterranean diet (accompanied with physical activity advice) vs. unrestricted caloric Mediterranean diet (with no advice on increase physical activity) | Mediterranean diet adherence score | 16S rRNA V4 hypervariable region sequencing |
Pagliai et al., 2020 | Italy | Crossover RCT | 3 months per intervention, 2-week wash-out period | N = 23; Adults aged 18–75 years with a low to medium cardiovascular risk profile (1–5% according to the guidelines of the European Society of Cardiology) | Age: 58.6 ± 9.8 years | Mediterranean diet vs. Vegetarian diet | 24-h diet recall, 9-item adherence score | 16S rRNA V3-V4 hypervariable region sequencing |
Petersen et al., 2022 | US | Crossover RCT | 4 weeks per intervention, 2-week wash-out | N = 56; Adults aged 30–75 years, with a BMI 25–35 kg/m2, abdominal obesity, and at least 1 other risk factor for CVD | Age: 45.0 ± 11.0 years BMI: 29.8 ± 2.9 kg/m2 | The American diet, supplemented with herbs and spices, was divided into three groups: low/moderate/high dose groups | Participants self-report | 16S rRNA V4 hypervariable region sequencing |
Roager et al., 2019 | Denmark | Crossover RCT | 8 weeks per intervention, 6-week wash-out period | N = 60; Adults aged 20–65 years who are weight stable, with a BMI of 25–35 kg/m2 and/or increased waist circumference, and at least one other CVD risk factor | Age: 48.6 ± 11.1 years; BMI: 28.9 ± 3.6 kg/m2 | Whole grain diet vs. refined grain diet | Diary; measured fasting concentrations of plasma alkylresorcinols | 16S rRNA gene sequencing and shotgun metagenomic sequencing |
Van Trijp et al., 2021 | Dutch | Parallel RCT | 12 weeks | N = 37; Adults aged 45–70 years, with a BMI 25–35 kg/m2 and an elevated plasma total cholesterol | Age: 60 ± 5.4, and 60 ± 6.0 years; BMI: 28 ± 2.0, and 27 ± 2.2 kg/m2 | Whole grain diet vs. refined grain diet | None | 16S rRNA V4 hypervariable region sequencing |
Vetrani et al., 2020 | Italy | Parallel RCT | 8 weeks | N = 78; Adults aged 35–70 years, with a BMI 27–35 kg/m2, increased waist circumference, and at least one or more components of MetS | Age: 54.0 ± 9.0. 56.0 ± 8.0, 53.0 ± 9.0, 55.0 ± 9.0 years; BMI: 33.0 ± 3.0, 32.0 ± 4.0, 32.0 ± 3.0, 30.0 ± 3.0 kg/m2 | Four diet patterns: (a) low LCn3&PP, diet low in LCn3 (1.5 g/day) and PP (365 mg/day); (b) high LCn3, diet high in LCn3 (4 g/day) and low in PP (363 mg/day); (c) high PP, diet high in PP (2903 mg/day) and low in LCn3 (1.4 g/day); and (d) high LCn3&PP, diet high in PP (2861 mg/day) and LCn3 (4 g/day) | 7-day food records | 16S rRNA |