Provide are a composition for forming a composite, the composition including a cellulose-based compound, a polyphenol-based compound, and a solvent, wherein an amount of the polyphenol-based compound is 1 to 40 parts by weight based on 100 parts by weight of the cellulose-based compound, a composite formed from the composition, and an orally ingestible composition including the composite. The composite has characteristics of being dissolved in a solvent in a various pH ranges depending on a mixing ratio of the cellulose-based compound and the polyphenol-based compound. Therefore, when the composite is used, a composite film may be easily prepared, and the composite film may be useful in medical or foods fields where film characteristics dependent on pH is required.