Efficacy of Polyphenols From Milk and Dark Chocolate

Dark chocolate is one of the richest sources of polyphenols, for example, a standard 40g portion of dark chocolate contains 400-800 mg of polyphenols, compared to red wine (170 mg /100ml) or an apple (200 mg/piece). Cocoa polyphenols, most notably the catechins, can exist in both lipid and water-based environments (amphipathic), meaning they can spare both lipophilic and hydrophilic vitamins. There have been a number of human trials conducted using chocolate or cocoa and measuring various endpoints. Most have been conducted with dark chocolate. An article in Nature found that the bioavailability of epicatechin from milk chocolate was substantially reduced compared to dark, and even dark taken with a glass of milk (Serafini et al 2003). The hypothesis was that the milk proteins bind to polyphenols, making them unavailable. Subsequent studies have not been able to reproduce this, but none have been conducted using solid chocolate as the first study, all have been done using a drink matrix, which may completely alter the binding interactions of the polyphenols and protein. To this end, this study is designed to compare solid chocolates as a source of polyphenols for improving a risk biomarker for vascular disease.

This study is designed as a blinded, three arm crossover trial. The primary outcome measure is to compare endothelial function after consumption of 3 chocolates (1 milk, 1 dark, 1 polyphenol-free control) with a secondary outcome of arterial stiffness. All volunteers will take all chocolate types in a crossover design. Subjects will undergo medical screening, anthropometry, physical activity and dietary assessments before randomization for the order of consumption.