Table 1.
Characteristics of included studies.
| Author, Country, Year | Clinical Trial Design | Population | Sex | Sample Size Chocolate/Placebo | Duration/Outcome | Intervention Group | |
|---|---|---|---|---|---|---|---|
| Intervention Group | Placebo Group | ||||||
| Ángel García-Merino, Spain, 2020 | Randomised, parallel-group placebo-controlled trial | Male endurance cross-country athletes | Male | 15/17 | 10 weeks | 5 g of fat-reduced cocoa containing 425 mg of flavanols | 5 g of maltodextrin |
| Fulton, USA, 1969 | Crossover, single-blind | Subjects with mild to moderate acne | Both | 65 | 2 months | 114 g of bittersweet chocolate bar | 112 g of 28% vegetable fat to mimic the lipids contained in chocolate liquor and cocoa butter bar |
| Cheng, China, 2018 | Randomised crossover 33 Latin-square design | Male or female aged 20–40 years | Both | 67 | 4 weeks | Cocoa butter | (1) Palm olein (2) extra virgin olive oil |
| Garcia-Yu, Spain, 2020 | Controlled randomised trial with two parallel groups | Women aged between 50 and 64 years and in the period of post-menopause | Female | 69/63 | 6 months | Chocolate (99% cocoa) 10 g as supplement | No intervention |
| Nishiwaki, Japan, 2019 | Randomised, controlled, parallel-group intervention study | Healthy Japanese college student | Both | 16/16 | 4 weeks | 20 g/day (508 mg of cacao polyphenol) of high-cocoa chocolate | No intervention |
| Wiese, Russia, 2019 | Randomised, parallel-five group placebo-controlled trial | Moderately obese volunteers | Both | 6 people per group | 4 weeks | 10 g of dark chocolate | (1) 7 mg GA lycopene (GAL) formulated with medium saturated fatty acids (GAL-MUFA) (2) 30 mg GAL-MUFA (3) 30 mg GAL-PUFA |
| Yoon, Korea, 2015 | Randomised, parallel-group placebo-controlled trial | Healthy female volunteers | Female | 31/31 | 24 weeks | Beverage containing 4 g cocoa powder to yield 320 mg total cocoa flavanols | Nutrient-matched cocoa-flavored beverage without cocoa flavanols |
| Shiina, Japan, 2019 | Randomised, placebo-controlled doubleblind crossover trial | Pre-diabetic volunteers | Both | 11/11 | 4 weeks | Cacao procyanidin supplement (83.3 ± 2.7 mg/day) which contain 13.9 ± 2.7 mg procyanidins | 240 mg dextrin |
| Baba, Japan, 2007 | Randomised controlled trial | Healthy Japanese male subjects | Male | 25 | 12 weeks | Cocoa powder and sugar | Sugar |
| Ibero-Baraibar, Spain, 2014 | Randomised, parallel and double-blind study | Healthy Caucasian adult | Both | 50 | 4 weeks | Cocoa extract | Placebo |
| Nickols-Richardson, USA, 2014 | Randomised controlled trial | Overweight otherwise healthy women age 25–45 years (premenopausal) | Female | 60 | 18 weeks | Cocoa beverage with dark chocolate | Cocoa free beverage with non- chocolate snacks |
| Njike, USA, 2011 | Randomised, controlled, crossover trial | Overweight, but otherwise healthy, men and women | Both | 44 | 6 weeks | Unsweetened or sweetened cocoa beverage | Non-cocoa beverage |
| Prereira, Portugal, 2014 | Randomised controlled trial | Clinically healthy individuals of Portuguese nationality, all undergraduate students at the Superior Polytechnic Institute of Coimbra, under the age of 25 years | Both | 60 | 4 weeks | Dark chocolate | Placebo |
| Ried, Australia, 2009 | Randomised controlled trial (2 phases) | Prehypertensive otherwise healthy adults | Both | 36 | 8 weeks | Dark chocolate bar | (1) Placebo (2) Tomato extract |
| Crews, USA, 2008 | Double-blind, placebo-controlled, randomised trial | Healthy older male and female adults 60 years and above | Both | 101 | 6 weeks | Dark chocolate bar | Placebo |