Kraft lignin, a by-product of the pulp and paper industry, was explored as an adsorbent for six dietary oils and was compared to chitosan, which is widely used in the pharmaceutical market. The dissolution and adsorption efficiency of kraft lignin were tested at an acidic pH corresponding to the stomach, as well as at a basic pH corresponding to the intestine. Results showed that kraft lignin is a powerful adsorbent that can take up dietary oils at up to about 6 times its own weight. Kraft lignin exhibits higher stability and insolubility at the pH of the stomach in comparison to chitosan. The adsorption isotherm of dietary oils fits well with the Freundlich model, and the adsorption kinetics follows a pseudo-second order relationship.