Biodisponibilidad y efectos biológicos de esteroles en bebidas funcionales

Based on the evidence of the ability of plant sterols (PS) to reduce LDL-cholesterol levels and the absence of adverse effects on human health, the European Society of Atherosclerosis (EAS) recommends daily consumption of PS. EAS considers a daily dose of 2 g of PS to be beneficial for individuals with hypercholesterolemia and moderate or low cardiovascular risk who do not qualify for pharmacotherapy, as well as for individuals under pharmacologic therapy who fail to reach therapeutic targets or display an intolerance to the therapy. Given that a usual diet is unable to offer the effective dose currently, several foods have been enriched with PS. The milk-based fruit beverages (where the addition of PS is allowed in the EU) are a convenient matrix to reach the daily recommended amount of PS. Moreover, these beverages are also considered healthy foods for their contribution in antioxidants (mainly carotenoids and β-critoxanthin (β-Cx)). Likewise, other functions such as antiinflammatory and anticarcinogenic effects have also been attributed to PS. The general objective of this Doctoral Thesis is to select and evaluate the functionality of a skimmed milk-based fruit beverage enriched with PS and containing β-Cx, through in vivo, ex vivo and in vitro studies. Three beverages (MFb: without fat addition; MFbM: with addition of milk fat and whey proteins enriched with milk fat globule membrane (MFGM); MFbO: with extra virgin olive oil and soy lecithin addition) have been studied, of which the MFbM is selected to carry out the clinical trial, based on the bioaccessibility (BA) of the PS (31.4%), and the possible health benefits attributed to MFGM. Under storage conditions (20-25ºC, 6 months), this beverage is stable, since no modifications were observed in the content and BA of PS, and their oxidation rate is low (0.022-0.023%). The consumption of the MFbM beverage, providing 2 g of PS, during 6 weeks by postmenopausal women, produces a hypocholesterolemic effect (reduction of total cholesterol (2.9%) and the LDL-cholesterol (5.1%)), as well as an antiinflammatory effect (reduction of proinflammatory cytokine IL-1β (6.7%) and increase of antiinflammatory IL-10 (22.5%)). It was demonstrated that the PS, at serum concentrations obtained after the intake of PS-enriched milk-based fruit beverage containing β-Cx, prevents hemolytic and partially proeryptotic effects induced by β-Cx with or without oxidative stress conditions in erythrocytes. The PS-ingredient (tall oil) used for enrichment of the beverage and its main PS (β-sitosterol), show an antiproliferative effect in breast (MCF-7), colon (HTC116) and cervical (HeLa) cancer cells. In addition, in models of colon cancer cells (Caco-2 and HT-29), it is shown that PS can act as coadjuvants of the chemotherapeutic agent 5-fluorouracil. Although more in vivo studies are necessary, the results obtained demonstrate the suitability and functionality of the designed and evaluated beverage with PS, β-Cx and MFGM.