Lipids as delivery systems to improve the biological activity of bioactive ingredients

Delivery systems in the form of lipids have been mainly developed for drugs in the pharmaceutical field, but lipids as delivery systems for bioactive ingredients can be extended to the functional food and nutraceutical fields. Lipid delivery systems may have considerable benefit by enhancing the transport of important bioactive molecules to different tissues, as well as improving the oral bioavailability of poorly water-soluble compounds. On the other hand, formation of lipid delivery systems leads to the lipophilization of compounds, which enhances the lipophile/hydrophile balance of molecules. Furthermore, mutual activity when the carrier used is another biologically active compound is of interest for lipid delivery systems. This review focuses on lipids as delivery systems of carrier-linked bioactive ingredients, namely triacylglycerols, phospholipids, fatty acids and fatty alcohols, sterols and alkylglycerols, as well as their inherent biological activity. The influence on the chemical stability, bioactivity, bioavailability or organ selectivity is addressed. In addition, the impact of lipophilization on other specific effects such as antioxidant will be described. Lipid delivery systems as carriers of bioactive fatty acids, phenolic compounds and vitamins will be the main examples illustrated.