**5.2 Gastric absorption**

Polyphenols are very poorly absorbed after ingestion and remain in the gastrointestinal tract, where they influence digestive enzymes activity, inhibiting crucial enzymes involved in the digestion of starch (α-amylase), lipids (pancreatic lipase), and protein digestibility (pepsin and trypsin). Digestibility is influenced by the polyphenol's interaction with food and endogenous proteins, like digestive enzymes, salivary proteins, gastric and intestinal mucosa, and other endogenous proteins on the luminal side of the intestinal tract [16, 69, 70]. Studies with *in vitro* simulation revealed that during gastric digestion (pH 1.2–2.0 in the presence of pepsin), there is a decrease in the recovery of phenolic compounds because they can interact with the pectin present in the food [29]. However, the presence of (+)-catechin has been evidenced in the stomach stage due to resistance to the acid environment [68].
