Table 4.

Anti-obesity effects of polyphenol-rich extracts in clinical trials.

Polyphenol	Subject	Country	Study Objective	Intervention	Key Observations	References
Polyphenol-rich green tea extract	N = 100, Women, age: 16–60 years BMI: >27 kg/m2	Taiwan	To examine the effect of green tea extract on obesity.	The subjects consumed green tea containing (491 mg of catechins containing 302 mg EGCG per day) for 12 weeks.	0.3% reduction in body weight (Equiv. 0.15 kg) after 12 weeks of treatment. Significantly reduced triglyceride levels.	[84]
Polyphenol-rich chocolate (contained mainly epicatechin)	N = 1017, Men and women aged: 20 to 85 years	USA	To evaluate the effect of chocolate rich in phenolic compounds on body mass index.	Subjects ate chocolate, with a mean intake of 2.0 (2.5) times/week and exercised 3.6 (3.0) times/week.	Improved BMI.	[85]
Yerba Mate (Ilex Paraguariensis) (rich in (quercetin rutin, chlorogenic and caffeic acids)	N  =  15 BMI  <  35 and  ≥ 25 kg/m2 and waist-hip ratio (WHR)   ≥ 0.90 for men or  ≥ 0.85 for women	Korea	To investigate the efficacy of Yerba Mate supplementation against obesity.	The subjects were given 13 g/day of Yerba Mate capsules for 12 weeks.	Decreased BMI (p  =  0.036), body mass fat (p  =  0.030), and waist-hip ratio (p  =  0.004).	[86]
Soya isoflavones	N = 100, postmenopausal women age: 50–70 years BMI 28–40 kg/m2	Canada	To assess the combined effect of exercise and soy isoflavones on obesity.	Subjects consumed a 70 mg/day dose of isoflavones for 12 months.	Decreased trunk fat mass and increased lean body mass.	[87]
Mixture of polyphenols	N = 573, 277 men, 296 women, age: 66.2–68.3 years BMI > 30 kg/m2	Spain	To assess the associations between total polyphenol and obesity parameters among the elderly after a long period of polyphenol intake (measured by overall urinary polyphenol level).	Participants known to consume foods rich in polyphenols were recruited and followed up for 5 years. Spot urine samples were collected and analyzed for total polyphenols, and obesity indicators were measured.	Increased consumption of dietary polyphenols was associated with improved BMI after 5 years of consumption.	[88]
Citrus polyphenolic extract of red-orange, grapefruit, and orange (Sinetrol-XPur)	N = 95, 55 women and 40 men, age: 22–45 years BMI 26–29.9 kg/m2	France	To investigate appropriate polyphenolic-rich combinations that would help reduce body fat, inflammation, and oxidative stress in overweight subjects.	Subjects consumed two capsules of citrus polyphenolic extract containing orange, grapefruit, sweet orange, and guarana daily for 12 weeks.	Reduced abdominal fat and overall body weight.	[83]
Polyphenol-rich green tea extract	N = 35, Men and women, mean, age 42.5 ± 1.7 years BMI: 36.1 ± 1.3 kg/m2	USA	To compare the effects of green tea polyphenols with controls on body weight and safety parameters in obese subjects.	Subjects took either four cups of decaffeinated green tea beverage or two capsules of green tea extract containing either 28 mg or 870 mg of catechins (GC, GCG, EC, ECG, EGC, and EGCG) daily for 8 weeks.	Decreased body weight. Improved LDL-cholesterol level	[89]
Licorice flavonoid oil	N = 22, men and women, age: 20–53 years BMI: 25.0–36.0 kg/m2	USA	To investigate the effect of licorice flavonoid oil supplementation on obesity-related health markers.	Subjects consumed three capsules of licorice flavonoid oil, 300 mg per day for 8 weeks.	Inhibited the total cholesterol level. Decreased total triglycerides.	[90]

LDL, low-density lipoprotein; HDL, high-density lipoprotein, LFO, licorice flavonoid oil; BMI, body mass index; GC, gallocatechin; GCG, gallocatechin-3-gallate; EC, epicatechin; ECG, epicatechin-3-gallate; EGC, epigallocatechin; EGCG, epigallocatechin-3-gallate.