Bioavailability of Carotenoids – Impact of High Mineral Concentrations

SCHEME: CORE

CALL: 2011

DOMAIN: SR - Sustainable Agro-Systems Management

FIRST NAME: Torsten

LAST NAME: Bohn

INDUSTRY PARTNERSHIP / PPP: No

INDUSTRY / PPP PARTNER:

HOST INSTITUTION: LIH

KEYWORDS: Carotenoids, Minerals, Bioavailability, Micellarization, Cellular Uptake, Gastrointestinal Digestion, Postprandial Study, Area under the Curve, Humans, In Vitro Models,

START: 2012-08-01

END: 2015-07-31

WEBSITE: https://www.lih.lu

Submitted Abstract

Background: Dietary intake of carotenoids, especially as fruits and vegetables, has been associated with potential health benefits, e.g. in the prevention of several chronic diseases. While data with respect to carotenoid intake is frequently available, much less is known on factors impacting their bioavailability, including the release from the food matrix, changes during gastro-intestinal digestion, and uptake by the epithelium. In general, carotenoid absorption is low (usually ca. 5-20%). Dietary factors known to alter carotenoid uptake and absorption include the positive impact of dietary lipids, and the negative effects of dietary fibre. A factor that has so far been neglected concerns minerals and trace elements. Our group has recently shown that higher concentrations of dietary minerals, including Ca, Mg, and also the trace elements Fe and Zn, can negatively impact micellarization in in-vitro test systems following simulated gastro-intestinal digestion, and also cellular uptake by Caco-2 cells. The underlying mechanisms remain speculative. It appears likely that minerals may form poorly soluble soaps in the presence of dietary lipids, the latter being crucial for the solubilization of carotenoids. These soaps become insoluble and would not be available for emulsification, and might further occlude carotenoids. In addition, minerals could react with bile acids, which are needed in the solubilization process of carotenoids. Albeit considerable amounts of minerals/trace elements were needed for the observed effect, these concentrations could be reached, at least for calcium and magnesium, from the diet, especially when considering dietary supplement intake.Proposed Study: In the suggested study, we aim to further investigate the negative impact that minerals appear to exert on the micellarization and cellular uptake of carotenoids, both in-vitro and in-vivo, from complete food items and/or supplements. For this purpose, we intend to investigate whether we observe, as earlier seen in Caco-2 cells, the same situation in more complicated cellular models and at various ranges of certain minerals/trace elements to different carotenoids, including, co-culture cell models such as Caco-2 and HT-29 mucus producing cells and to study the effect of various conditions of bile concentration, pH, time, and others. Also, we wish to determine to what extent micelle size and number are affected by the minerals. Furthermore, we intend to perform a human study to confirm/or reject our hypothesis based on the earlier cell trials, that carotenoids are impacted by minerals in the diet (supplements), at least at 3 different ratios (minerals/carotenoids) that we wish to test. Materials and Methods: Within the in-vitro investigations we will study additional factors affecting the interaction of minerals and carotenoids, on micellarization and uptake, e.g. micelle size, that cannot easily be done in humans, using Caco-2 and co- culture cell models (e.g. HT-29/Caco-2 model). However, human studies are still considered as the “gold standard” for testing bioavailability. Thus we aim, together with the CRP-Santé, to study the impact of various Ca to carotenoid ratios in test meals enriched with these 2 compounds. For this purpose, we will conduct a human postprandial crossover study with ca. 12-20 healthy candidates (age 19-60, m/f), and study newly absorbed carotenoids in the triacylglycerol-rich lipoprotein fraction as the area under the curve (AUC) over 10 h. Emphasis should also be given on the absorption of epoxycarotenoids and degradation products (furanoids).Expected results: We hope that this study will reveal whether/to what extent, minerals/trace elements have the potential to alter micellarization, uptake, and absorption of carotenoids, which could be especially important for dietary supplements, and many stakeholders in this domain.

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