Alkaline phosphatase, intestinal, also known as ALPI, is a type of alkaline phosphatase that in humans is encoded by the ALPI gene. Its chemical formula is:C₂₆₇₉H₄₁₉₆O₉₆₅N₆₇₂S₁₈P₂.

Intestinal alkaline phosphatase is an endogenous enzyme that maintains gut homeostasis. It detoxifyies bacterial toxins, dephosphorylates phosphorylated nucleotides, regulates lipid absorption in the intestine, and regulates the microbiome in the intestine. In addition to these functions, intestinal alkaline phosphatase can also modulate bicarbonate secretion and can modulate the pH of the duodenum.