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.