Table 3.

Summary of results from clinical trials of polyphenols in individuals with MetS.

Authors, year	Sources	Main polyphenols	Individuals	Duration	Bioactivities	Improvements
(Faghihzadeh, Adibi et al. 2015) [15]	Resveratrol capsules	Resveratrol	50 NAFLD patients	12 weeks	ND	ALT↓, hepatic steatosis↓
(Costabile, Vitale et al. 2018) [21]	Red grape pomace	Anthocyanins, flavan-3-ol, procyanidins	12 healthy men	1 week	ND	Postprandial insulin incremental area↓, insulin secretion index↓, IS index↑
(Fang, Kim et al. 2018) [22]	Mango	Gallic acid, gallotannin, galloylglycosides, flavonoids	12 lean and 9 obese participants	6 weeks	Anti-inflammation: IL-8↓ and MCP-1 ↓.	In lean participants: systolic BP↓ In obese participants: HbA1c and PAI-1↓
(Dallas, Gerbi et al. 2014) [27]	Sinetrol-XPur	Catechin, naringin	95 overweight subjects	12 weeks	Antioxidation: MDA↓, SOD↑, GSH↑ Anti-inflammation: CRP↓, fibrinogen↓	Waist and hip circumference↓, abdominal fat↓, body weight↓
(Astell, Mathai et al. 2013) [28]	C. fimbriata extract	Gallic acid	43 overweight and obese subjects	12 weeks	ND	Waist circumference↓, WHR↓ palatability of the test meal↓, sodium intake↓, body weight↓, BMI↓, hip circumference↓, systolic BP↓, HR↓, TG↓, total fat and saturated fat intake↓
(Taubert, Roesen et al. 2007) [36]	Cocoa-containing foods	Ericatechin, procyanidin dimer, flavonols	44 untreated upper-range prehypertension or stage 1 hypertension	18 weeks	Antioxidation: fasting plasma levels of S-nitrosoglutathione↑	Systolic BP↓, diastolic BP↓, hypertension prevalence↓
(Rangel-Huerta, Aguilera et al. 2015) [38]	Orange juice	Anthocyanins	100 obese or overweight adults	12 weeks	Antioxidation: 8-OHdG↓, GR↓, erythrocyte catalase↓, 8-isoPGF2α↓, SOD↑	Body mass index↓, waist circumference↓, leptin↓, systolic and diastolic BP↓
(Chai, Davis et al. 2018) [39]	Tart cherry juice	Gallic acid	17 men and 20 women	12 weeks	ND	Systolic BP↓, LDLC↓, TC↓
(Erlund, Koli et al. 2008) [41]	Berry	Quercetin, caffeic acid, vanillic acid,	72 unmedicated subjects with cardiovascular risks	8 weeks	ND	HDLC↑, systolic BP↓
(Samavat, Newman et al. 2016) [42]	Green tea	Catechins	936 women	12 months	ND	Circulating TC↓, LDLC↓ Non-HDLC↓.
(Faghihzadeh, Adibi et al. 2014) [46]	Resveratrol capsules	Resveratrol	50 NAFLD patients	12 weeks	Anti-inflammation: IL-6↓, NF-κB activity↓, serum CK-18 ↓	Weight↓, body mass index↓, waist circumference↓, ALT↓, hepatic steatosis grade↓
(Chen, Zhao et al. 2015) [47]	Resveratrol capsules	Resveratrol	60 NAFLD patients	3 months	Anti-inflammation: NF-κB activity ↓, serum CK-18 ↓	AST↓, glucose↓, LDLC↓, ALT↓, TC↓HOMA-IR↓TNF-α↓, CK-18 fragment↓, FGF21↓, adiponectin level↑
(Martinez-Maqueda, Zapatera et al. 2018) [65]	Dried grape pomace	Anthocyanins, flavan-3-ol	50 participants with at least one phenotype of MetS	6 weeks	ND	IR↓, fasting insulinemia↓, Is↑
(Tynkkynen, Mursu et al. 2012) [66]	Chocolate	Epicatechin	45 nonsmoking volunteers	3 weeks	Antioxidation: oxidation susceptibility of serum lipids↓	HDL↑
(Mursu, Voutilainen et al. 2005) [67]	Polyphenol-rich phloem	Catechins	75 nonsmoking hypercholesterolemic men	4 weeks	Antioxidation: Oxidation resistance of total serum lipids↑	Lipid peroxidation↓
(Espinosa-Moncada, Marin-Echeverri et al. 2018) [68]	Vaccinium meridionale Swartz (agraz)	Anthocyanins	40 women with MetS	4 weeks	Antioxidation: serum antioxidant capacity↑, urinary 8-OHdG ↓ Anti-inflammation: Hs-CRP levels ↓	Serum antioxidant capacity↑, DNA oxidative damage↓
(Vetrani, Vitale et al. 2018) [69]	ND	Flavonoids, flavan-3-ols, phenolic acids, flavonols	78 individuals with at least one features of the MetS	8 weeks	Antioxidation: urinary isoprostanes↓	Postprandial lipid response↓, VLDL↓, early insulin secretion↑
(Chiva-Blanch, Urpi-Sarda et al. 2013) [70]	Red wine	Catechin, epicatechin, malvidin-3-glucoside, gallic acid	73 male moderate alcohol consumers	4 weeks	ND	Plasma insulin↓, HOMA-IR↓, HDLC↑, Apo A-I↑, Apo A-II↑, lipoprotein↓

(↓): decrease; (↑): increase; ND: not detected. MetS: metabolic syndrome; IR: insulin resistance; IS: insulin sensitivity; IL: interleukin; MCP-1: monocyte chemotactic protein-1; HbA1c: glycosylated hemoglobin; PAI-1: plasminogen activator inhibitor 1; BP: blood pressure; MDA: malondialdehyde; SOD: superoxide dismutase; GSH: glutathione; CRP: C-reactive protein; WHR: waist to hip ratio; BMI: body mass index; HR: heart rate; TG: triacylglycerol; LDLC: low-density lipoprotein cholesterol; 8-OHdG: 8-hydroxydeoxyguanosine; GR: glutathione reductase; HDLC: high-density lipoprotein cholesterol; TC: total cholesterol; VLDL: very low-density lipoprotein; NAFLD: nonalcoholic fatty liver disease; ALT: alanine aminotransferase; NF-κB: nuclear factor-kappa B; CK: cytokeratin; FGF: fibroblast growth factor; 8-isoPGF2α: 8-iso-prostaglandin F2α; AST: aspartate aminotransferase; HOMA-IR: homeostasis model assessment insulin resistance index; TNF-α: tumor necrosis factor-alpha; hs-CRP: high-sensitivity C-reactive protein; Apo: apolipoprotein.