A prepared food product for ingestion by mammals is described and methods for preparing such products. The food product includes an oxidation-resistant fat-based composition substantially free of exogenous solubilizing and dispersing agents for phytosterols. The fat-based composition includes between 75% and 98% by weight of at least one triglyceride-based edible oil or fat, and between 2% and 25% by weight of non-esterified phytosterols. Typically, approximately 1.5% by weight of phytosterols remain soluble at room temperature, and between 0.5% and 23.5% by weight are converted to triglyceride-recrystallized phytosterols (TRPs). The fat-based composition which has been partially oxidized in the prepared food by exposure to air (and typically heat), contains a reduced amount of oxidative by-products compared to a similar fat-based composition lacking these non-esterified phytosterols.