The efficiency (dose response) of cholesterol-lowering effect of phytosterols in humans depends on their chemical forms (derived or non-derived) and formulation methods in a delivery system. With a series of synthesized beta-sitosteryl fatty acid esters (C2:0-C18:0 and C18:1-C18:3), this work examined their thermal properties and applications in preparation of nanodispersion with beta-sitosterol as a comparison. Inspection of the melting point (T-m) and the heat of fusion (Delta H) of beta-sitosteryl fatty acid esters and the chain length and unsaturation degree of fatty acyl moiety revealed a pronounced structure-property relationship. The nanodispersions prepared with beta-sitosterol and beta-sitosteryl saturated fatty acid (SFA) esters displayed different particle size distribution patterns (polymodal vs bimodal), mean diameter (115 nm vs less than 100 nm), and polydispersity index (PDI) (0.50 vs 0.23-0.38). beta-sitosteryl unsaturated fatty acid (USFA) esters showed a distinctly different dispersion behavior to form nanoemulsions, rather than nanodispersions, with more homogeneous particle size distribution (monomodal, mean diameter 27-63 nm and PDI 0.18-0.25). The nanodispersion of beta-sitosteryl medium chain SFA ester (C14:0) demonstrated a best storage stability. (C) 2013 Elsevier Inc. All rights reserved.