Table 3.
Summary of interventional trials with polyphenol-rich foods on metabolic syndrome.
| Ref. | Type of study | Number of patients | Patients' characteristics | Age (years) | Intervention | Dose | Duration | Measured outcomes | Results |
|---|---|---|---|---|---|---|---|---|---|
| [92] | Placebo-controlled | 48 | Postmenopausal women with pre- and stage 1 hypertension | 55–65 | Blueberries | 22 g/day powder | 8 weeks | Blood pressure, arterial stiffness, CRP, nitric oxide, and superoxide dismutase | Decreased blood pressure and arterial stiffness and increased nitric oxide after blueberry intervention: no effects on CRP |
| [91] | Placebo-controlled | 48 | MetS | 47–53 | Blueberries | 50 g/day powder | 8 weeks | Blood pressure, lipid profile, HOMA index, oxidation, and inflammation parameters | Decreased blood pressure, no changes in body weight, HOMA index or lipid profile. Decreased oxLDL, MDA, and HNE. No changes in inflammatory biomarkers |
| [99] | Placebo-controlled | 44 | MetS | 53–61 | Blueberries | 45 g/day powder | 6 weeks | Blood pressure, endothelial function, and insulin sensitivity | Improved endothelial function. No changes in blood pressure or insulin sensitivity |
| [100] | Placebo-controlled | 32 | Obese, nondiabetic, and insulin-resistant | 46–57 | Blueberries | 45 g/day powder | 6 weeks | Insulin sensitivity, inflammatory biomarkers, and adiposity | Improved insulin sensitivity but no changes in adiposity or inflammatory biomarkers |
| [98] | Placebo-controlled | 27 | MetS | 43–59 | Bilberries | 400 g fresh | 8 weeks | Body weight, blood pressure, glucose, lipid profile, and inflammatory parameters | Decreased CRP, IL-6, IL-12, and LPS concentrations and decreased expression of MMD and CCR2 in monocytes. No changes in body weight, blood pressure, glucose, or lipid metabolism |
| [90] | Placebo-controlled | 31 | MetS women | 46–60 | Cranberries | 480 mL/day juice | 8 weeks | Blood pressure, glucose and lipid profile, markers of inflammation, and oxidation | Increased plasma antioxidant capacity and decreased oxLDL and MDA. No changes in blood pressure, glucose and lipid profiles, CRP, and IL-6 |
| [93] | Placebo-controlled | 23 | MetS women | 40–60 | Pomegranate | 300 mL/day juice | 6 weeks | Lipid peroxidation and phospholipid fatty acid composition of plasma and erythrocytes, blood pressure, and lipid profile | Decreased plasma arachidonic acid and increased saturated fatty acids. Decreased TBARS and arachidonic acid and increased monounsaturated fatty acids in erythrocytes. No changes in blood pressure or lipid profile |
| [94] | Placebo-controlled | 102 | MetS | 43–60 | Extra virgin olive oil | 10 mL/day | 90 days | Blood pressure, BMI, HOMA index, lipid profile, CRP, and oxidative parameters | Decreased waist perimeter and increased TRAP but no changes in blood pressure, lipid profile, HOMA index, BMI, or CRP |
| [112] | Placebo-controlled | 65 | Normal and overweight | 18–50 | Green tea extract | 9 capsules/day containing >0.06 g EGCG and 0.03–0.05 g caffeine per capsule | 12 weeks | Body weight, fat mass index, resting energy expenditure | No differences in body weight, fat mass index, or resting energy expenditure |
| [113] | Placebo-controlled | 27 | MetS | 25–80 | Grape seed extract | 300 or 150 mg/day | 4 weeks | Serum lipids, blood glucose, and blood pressure | Decreased blood pressure. No changes in glucose or lipid profile. No differences between doses |
| [101] | Randomized crossover | 24 | MetS men | 30–70 | Grape seed powder or placebo | 46 g/day (267 mg polyphenols) | 30 days | Blood pressure, endothelial function, lipid profile, glucose, and body weight | Decreased systolic blood pressure and ICAM-1 and increased FMD. No differences in diastolic blood pressure, nitric oxide, body weight, glucose, or lipids |
| [114] | Randomized crossover | 10 | MetS | Red wine and dealcoholized red wine | 272 mL/day | 30 days | Body weight, blood pressure, glucose and insulin, lipid profile, CRP, and LPS | Decreased systolic and diastolic blood pressure, glucose, triglycerides, total cholesterol, CRP, and LPS and increased serum levels of HDL cholesterol. No changes in body weight | |
| [95] | Randomized parallel | 75 | MetS | 55–80 | Mediterranean diet supplements with extra virgin olive oil or nuts and control diet | — | 5 years | Catalase, SOD, myeloperoxidase, and XOX activities and protein levels; protein carbonyl derivatives; and nitrotyrosine, nitrite, and nitrate levels | Increased plasma activity and protein levels of SOD and catalase, increased plasma nitrate levels, and decreased XOX activity in the Mediterranean diets compared to the control diet |
| [96] | Case-control | 36 | MetS and healthy individuals | 42–64 | Mediterranean diet | — | 3 months | Insulin resistance and oxidative and inflammatory status | Decreased plasma, erythrocyte, and platelet antioxidant enzymes and a rise in lipid and protein oxidation, plasma CRP, and fibrinogen in MetS patients |
| [103] | Randomized parallel | 180 | MetS | 37–50 | Mediterranean diet and prudent diet | — | 2 years | Endothelial function score, lipid profile and glucose, insulin sensitivity, circulating levels of CRP, and IL-6, IL-7, and IL-18 | Decreased body weight and insulin resistance, decreased concentrations of CRP, IL-6, IL-7, and IL-18, and improved endothelial function score in the Mediterranean diet group |
| [102] | Randomized controlled | 35 | MetS | 40–44 | Green tea | Green tea (4 cups/day), green tea extract (2 capsules and 4 cups water/day) | 8 weeks | Body weight, lipid profile, blood pressure, and inflammatory biomarkers | Decreased total and LDL cholesterol after green tea extracts. No changes in body weight, blood pressure or in serum levels of adiponectin, CRP, IL-6, IL-1β, VCAM-1, ICAM-1, leptin, or leptin : adiponectin ratio |
| [105] | Randomized parallel | 86 | Overweight/obese individuals with a large waist circumference and any other component of the metabolic syndrome | 44–64 | Isoenergetic diets with high and low polyphenol content | — | 8 weeks | Fasting and postmeal TRLs and 8-isoprostane concentrations | Reduced fasting triglyceride concentrations and large VLDL, reduced postprandial triglyceride total area under the curve in plasma and large VLDLs, and decreased urinary 8-isoprostane after high polyphenol intake |
| [52] | Case-control | 24 | Healthy and MetS | 27–38 | Extra virgin olive oil | 50 mL/single dose | Acute | Glycemia, insulin sensitivity, lipid profile, and gene and miRNA expression of peripheral blood mononuclear cells | Improved glycemia and insulin sensitivity in healthy subjects but not in MetS patients. No changes in lipid profile in either population |
Ref.: reference number; MetS: metabolic syndrome; HOMA: homeostasis model assessment of β-cell function and insulin resistance; BMI: body mass index; CRP: C-reactive protein; LPS: lipopolysaccharide; SOD: superoxide dismutase; XOX: xanthine oxidase; IL: interleukin; TRL: triglyceride-rich lipoprotein; oxLDL: oxidized low-density lipoprotein; VLDL: very low-density lipoprotein; MDA: malondialdehyde; HNE: hydroxynonenal; MMD: monocyte-to-macrophage differentiation-associated; CCR2: C-C motif chemokine receptor 2; TBARS: thiobarbituric acid reactive substances; TRAP: total peroxyl radical-trapping antioxidant potential; ICAM-1: intercellular adhesion molecule-1; VCAM-1: vascular adhesion molecule 1; FMD: flow-mediated dilation.