Stanol ester is a heterogeneous group of chemical compounds known to reduce the level of low-density lipoprotein (LDL) cholesterol in blood when ingested,  though to a much lesser degree than prescription drugs such as statins .  The starting material is phytosterols from plants. These are first hydrogenated to give a plant stanol which is then esterified with a mixture of fatty acids also derived from plants. Plant stanol esters are found naturally occurring in small quantities in fruits, vegetables, nuts, seeds, cereals, legumes, and vegetable oils.
Sterols are essential for all eukaryotes . In contrast to animal and fungal cells, which contain only one major sterol, plant cells synthesize an array of sterol mixtures in which sitosterol and stigmasterol predominate.  Sitosterol regulates membrane fluidity and permeability in a similar manner to cholesterol in mammalian cell membranes.  Plant sterols can also modulate the activity of membrane-bound enzymes.  Phytosterols are also linked to plant adaptation to temperature and plant immunity against pathogens.