Cocoa flavanol interactions with intestinal sugar metabolism

The interaction between cocoa polyphenols and sugars was investigated in the Caco-2 cell model. Previous investigations have suggested a link between sugar content of a food/meal and epicatechin bioavailability. To investigate this hypothesis further, the effect of sucrose, glucose and fructose on epicatechin absorption across the Caco-2 monolayer was studied, and is presented here. Apical to basolateral transport of epicatechin was enhanced by co-incubation with sucrose, but not glucose or fructose. It is proposed that sucrose-induced cell signalling stimulated activity of the sodium-dependent glucose transporter SGL T1, which lead to widening of tight junction pore size. Consequently paracellular permeability of epicatechin was enhanced. The presence of glucose or fructose, but not sucrose, reduced the total concentration of methylated epicatechin produced by Caco-2 cells. Decreased formation of methylated epicatechin is hypothesised to be a consequence of catechol-O-methyl transferase inhibition (COMT). COMT requires a magnesium cation cofactor, which is also required by some glycolytic enzymes. It is suggested that competition for the magnesium (11) cofactor leads to reduced epicatechin methylation. Flavanol-rich dark chocolate extract also reduced total methylation of epicatechin. It is proposed that flavanols with a degree of polymerisation greater than monomer compete with epicatechin for methylation.