Effects of Polyphenol Intake on Metabolic Syndrome: Current Evidences from Human Trials

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.