3.3. In Vitro Study
In order to substantiate the clinical effects of cocoa-derived polyphenols on gut permeability, we performed an in vitro study with the phenolic fraction extracted from dark chocolate.Firstly, we investigated the effects of different concentrations of LPS (0–120 pg/mL) on epithelial cell viability to choose a non-toxic concentration. We decided to test the concentrations of LPS we found in elite athletes’ serum to verify the effects of physiologically relevant concentrations of LPS on intestinal epithelial cells. Caco-2 cells incubated with 0–120 pg/mL LPS for 48 h showed no statistical differences in cell viability, regardless of the dose of LPS, indicating that 0–120 pg/mL LPS has no cytotoxic effects on Caco-2 cells (Moreover, to determine whether polyphenol extracts (PPs) had toxic effects, Caco-2 cells were incubated with PPs (0, 25, 50, and 100 μg/mL) for 48 h at concentrations relatively similar to those found in the serum of elite football athletes after dark chocolate intake [