Description succincte
(Anglais)
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Recent developments in biofortification resulted in crops rich in iron and zinc. However, the bioavailability of micronutrients from biofortified crops has so far not been demonstrated. The aim of the proposed project is to assess zinc (and iron) bioavailability of micronutrient biofortified wheat using stable isotopes and to compare it to the bioavailability of conventionally fortified wheat flour. The results will demonstrate the usefulness of biofortification as a strategy for preventing and combating human zinc (and iron) deficiency.
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Partenaires et organisations internationales
(Anglais)
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AT, BE, BG, CH, CZ, DE, DK, EL, ES, FI, FR, HU, IL, IT, LT, LU, NL, NO, PL, PT, RO, RS, SE, SI, SK, TR, UK
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Résumé des résultats (Abstract)
(Anglais)
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Although biofortification of staple crops is a promising strategy to improve the zinc (Zn) status of deficient populations, few studies have evaluated the bioavailability and absorption potential of these crops. Furtherore, methodologically, the validity of thypical assumptions made when assessing mineral bioavailability with stable isotopic labels, the state of the art method, needs to be assessed. It is unclear whather externally added zinc tracer substances (extrinsic labels) are absorbed similarly as the zinc intrinsically expressed by the wheat plant. As the Zn is embedded in the food matrix, the commonly used extrinsic labeling method (adding a tracer substance to the food prior consuption) might not deliver accurate absorption measurements. The goal of this projects are therefore: 1) to produce intrinsically labelled wheat via hydroponic culture (Prof. Frossard, ETH Zürich) and characterize its zinc content; 2) to quantify the Zn absorption in human subjects when the wheat is either intrinsically or extriniscally labelled with stable zinc isotopic tracers. Eighteen healthy adults consumed the three different meals after a 30 day wash-out period. Fractional absorption of Zn (FAZ) was then measured using the double isotopic tracer ratio technique. Intrinsic and extrinsic Zn absorption measurements were strongly correlated (R2=0.94) and the average extrinsic/intrinsic absorption ratios were 1.03 for the conventionally fortified meal and 1.02 for the biofortified meal. These findings show that the fortification and biofortification Zn are absorbed in a comparable manner and that the two strategies are efficient in meeting the Zn requirements of deficient populations. Biofortified wheat could become a good source of Zn for populations consuming high quantities of this crop. Moreover, extrinsic labeling method can further be relied on when measuring zinc absorption in humans from wheat-based meals.
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