Intrinsic labelling of different foods with stable isotope of zinc (⁶⁷Zn) for use in bioavailability studies

Abstract

~~Intrinsically-labelled foods are required to validate extrinsic-labelling techniques used to study the bioavailability of trace elements. Wheat (Triticum aestivurn), peas (Pisum sativum), goat's milk, human milk, eggs and chicken meat were selected for intrinsic-labelling studies with 67Zn. Peas were grown hydroponically in enriched nutrient solution and wheat was grown in sand and watered with enriched nutrient solution. Some of the wheat plants were also given stem injections of 67Zn solution. Eggs and chicken meat were prepared by administering 67Zn intravenously to chickens, and human milk was collected after an oral dose of 67Zn in a cola drink. All the foods investigated were sufficiently enriched with 67Zn for Zn absorption studies except wheat prepared by the sand and water-culture method.

Holmium as a faecal marker for copper absorption studies in adults

“…Sunflower (Helianthus annuus) seeds and soya beans (Glycine max) were intrinsically labelled with the highly enriched '&Cu stable isotope by cultivating the plants using hydroponic techniques [6]. Copper concentrations and isotope enrichments were determined by AAS and ICP-MS respectively.…”

Assessment of zinc bioavailability: studies in rats on zinc absorption from wheat using radio- and stable isotopes

“…A third experiment was performed in which the effect of a dietary modifier of Zn absorption (meat) on wheat was investigated: Expt 3, the effect of chicken meat on Zn absorption from wheat was studied using chicken meat and wheat intrinsically labelled with 67Zn prepared as described elsewhere (Fox et al 1991). Three groups of fourteen rats each were used : group 1, fed on 6.0 g wheat; group 2, 7.2 g chicken meat; group 3, 3.6 g chicken meat mixed with 3.0 g wheat.…”

“…Extrinsically-labelled 67Zn wheat was prepared by adding a solution of elemental Zn (91.9% 67Zn (atom%); Technical and Optical Equipment, London)) dissolved in a minimum volume of HCl (AR) and made up to a suitable volume with distilled water to non-enriched wheat 2 h before consumption. The test meal labelled with the radioisotope 65Zn was prepared by adding 18.5 kBq 65Zn (ZnC1,; Amersham International) to 7 g 67Zn-enriched wheat, prepared as described previously (Fox et al 1991). The non-enriched wheat was grown from the same batch of seeds and under the same conditions as the enriched wheat.…”

Apparent zinc absorption by rats from foods labelled intrinsically and extrinsically with 67Zn

“…The 67Zn-labelled foods were prepared as described elsewhere (Fox et al 1991). The isotope had either been incorporated into the food previously or was added to non-enriched food as a solution of elemental Zn (91.9% "Zn (atom YO); Technical and Optical Equipment, Edgware Road, London NW9 6EE) in dilute hydrochloric acid (AR) at least 1 h before consumption.…”