7-ketocholesterol in human and adapted milk formulas

In the last few years, a variety of experimental and clinical studies concerning the formation, metabolism, and cellular effects of cholesterol oxidation products (COPs) have been carried out. Nevertheless, a substantial lack of knowledge exists regarding the possible intake of these compounds by the newborn through human and/or adapted formula milk. As far as the pathological role of COPs is concerned, exhaustive studies have shown that since dietary COPs are cytotoxic and atherotoxic, they may lead to adverse effects on health. The aim of this study was to investigate the possible development of cholesterol oxidation in adapted formula and in human milk by comparing the main cholesterol oxidation biomarker (7-ketocholesterol) concentration in both. To do so, the total (bonded and free) 7-ketocholesterol content was measured in ten fresh human mature milk samples and in ten milk adapted formula samples by high performance liquid chromatography and diode array detection. The 7-ketocholesterol human milk content (0.7+/-0.3) was often below the quantifiable limit (0.5 microg/g of extracted lipids) while 7-ketocholesterol adapted milk concentrations were often above (3.6+/-4.0) this limit. The 7-ketocholesterol content of adapted formula samples was significantly higher as compared to human milk samples (P<0.05). This is the first study to provide data concerning the concentrations of cholesterol oxides in human milk and in formula milk. Our results clearly suggest that the manufacturing technologies employed and the nutrient extractive sources play a crucial role in the development of cholesterol oxides in the end product. Careful surveillance has to be paid in order to avoid alteration of bioactive properties of nutrients and/or development of potentially toxic derivative compounds.