Helen Crews

The determination of the authenticity of wine from its trace element composition

Multi-element analysis of 112 Spanish and English wines by inductively coupled plasma mass spectrometry (ICP-MS) was undertaken to ascertain whether or not this method could provide data for determining the region of origin of wine. Flow injection analysis proved superior to continuous nebulisation. Quality assurance of these measurements proved entirely satisfactory and was typical of that previously established for this technique. An intercomparison exercise with another expert laboratory showed satisfactory agreement. The data was examined using the statistical technique of discriminant analysis. This was able to unequivocally identify the region of origin of Spanish wines from three different regions. It was also possible to completely differentiate English and Spanish white wines. If red and rose wines were included in the Spanish set, the English and Spanish populations could be distinguished with 95% accuracy. This preliminary study has indicated the power which multi-element analysis can bring to determining the region of origin of wines. At present, no other technique has the ability to perform this categorisation.

Trace element speciation for environment, food and health.

Trace Elemant Speciation for Environment, Food and Health , Trace Elemant Speciation for Environment, Food and Health , کتابخانه دیجیتال جندی شاپور اهواز

Interlaboratory trial on the determination of the In Vitro iron dialysability from food

An in vitro method for the estimation of iron bioavailability was subjected to an interlaboratory trial. The method involved a simulated gastrointestinal digestion using pepsin for the gastric stage followed by pancreatin and bile salts for the intestinal stage. The proportion of iron diffused through a semipermeable membrane (molecular mass cut-off 10 kDa) was used to measure the iron dialysability. An interlaboratory trial between nine laboratories was conducted to evaluate the repeatability and reproducibility of the agreed method. The reproducibility of the method among the participating laboratories was 20-30% and depended on the content of dialysable iron. Several factors contributing to the variation in the in vitro dialysability among laboratories are discussed. The pH adjustment in the intestinal digestion was identified as one of the critical parameters. The present in vitro method was used to evaluate the iron dialysability from three meals. The dialysability data were in reasonable agreement with human absorption data. The usefulness of the in vitro dialysability method is discussed.

Handbook of Elemental Speciation: Techniques and Methodology

Different techniques and methods have been developed for (15) Cornelis, R., Crews, H., Caruso, J. and Heumann, K., Handbook of elemental speciation: Techniques and methodology, Chapter 5.9. Speciation Analysis by Electrochemical. 1.1.2 Magnetic Sector Field Devices for Elemental and Isotopic Analysis in Handbook of Elemental Speciation: Techniques and Methodology, eds. Indiana University Course C612SPECTROCHEMICAL METHODS OF (22) “Handbook of Spectroscopy (Book Review)”, Andrade, F.J., Ray, S.R., and Hieftje, Seminar: “New Techniques and Instrumentation for Elemental Speciation.”.

Bioavailability of selenium from fish, yeast and selenate:a comparative study in humans using stable isotopes

Objective: To measure the bioavailability of selenium from cooked and raw fish in humans by estimating and comparing apparent absorption and retention of selenium in biosynthetically labelled fish with labelled selenate and biosynthetically labelled selenium in brewers yeast.Design: The intervention study was a parallel, randomised, reference substance controlled design carried out at two different centres in Europe.Setting: The human study was carried out at the Institute of Food Research, Norwich, UK and at TNO Nutrition and Food Research, Zeist, The Netherlands.Subjects: In all, 35 male volunteers aged 18–50 y were recruited; 17 subjects were studied in Norwich (UK) and 18 in Zeist (Netherlands). All of the recruited subjects completed the study.Interventions: Biosynthetically labelled trout fish (processed by two different methods), biosynthetically labelled brewers yeast and isotopically labelled selenate were used to estimate selenium apparent absorption and retention by quantitative analysis of stable isotope labels recovered in faeces and urine. Subjects consumed the labelled foods in four meals over two consecutive days and absorption was measured by the luminal disappearance method over 10 days. Urinary clearance of isotopic labels was measured over 7 days to enable retention to be calculated.Results: Apparent absorption of selenium from fish was similar to selenate and there was no difference between the two processing methods used. However, retention of fish selenium was significantly higher than selenate (P<0.001). Apparent absorption and retention of yeast selenium was significantly different (P<0.001) from both fish selenium and selenate.Conclusions: Fish selenium is a highly bioavailable source of dietary selenium. Cooking did not affect selenium apparent absorption or retention from fish. Selenium from yeast is less bioavailable.

A critical assessment of some biomarker approaches linked with dietary intake

In this review many examples are given of the complexities involved in using some biomarkers in relation to assessing the effects of dietary exposure, when there is frequently a need to determine changes following long-term low level exposure to dietary components. These range from understanding why the biomarker might be valuable and how best it can be measured, to the pitfalls which can occur in the interpretation of data. Analytical technique is considered in relation to folate and selenium, and flavonoid and carotenoid species are used to illustrate how the metabolism of a compound may alter the validity or adequacy of a marker. Vitamin A is discussed in relation to the difficulties which can arise when there are several biomarkers that may be available to assess exposure to one nutrient. Vitamin B12 is discussed in relation to the dietary choices made by individuals. Possible interactions and the role of measuring total antioxidant capacity is considered in some detail. In contrast to most nutrients, there is a marked lack of biomarkers of either exposure or effect for most non-nutrients. The role of biological effect monitoring is considered for dietary contaminants, fumonisins and polyhalogenated aromatic hydrocarbons. Aflatoxins are discussed to exemplify food contaminants for which the biomarker approach has been extensively studied. Finally some compounds which are deliberately added to foods and some which appear as processing contaminants are each considered briefly in relation to the requirement for a biomarker of exposure to be developed.

Handbook of Elemental Speciation II - Species in the Environment, Food, Medicine and Occupational Health: Cornelis/Handbook of Elemental Speciation II - Species in the Environment, Food, Medicine and Occupational Health

Handbook of Elemental Speciation II: Species in the Environment, Food, Medicine and Occupational Health Rita Cornelis (Editor-in-Chief), Joseph A. Caruso (Associate Editor), Helen Crews (Associate Editor), Klaus G. Heumann (Associate Editor) E-Book 978-0-470-85599-7 September 2005

Lack of effect of dietary chromium supplementation on glucose tolerance, plasma insulin and lipoprotein levels in patients with type 2 diabetes

482.99 Hardcover 978-0-470-85598-0 June 2005

Bromine and iodine in 1997 UK total diet study samples

603.25 O-Book 978-0-470-85600-0 October 2005 Available on Wiley Online Library

Adaptive responses in men fed low- and high-copper diets

Chromium is essential for the regulation of insulin action, thereby influencing carbohydrate and lipid metabolism. An uncontrolled pilot study was designed to measure the habitual daily intake of chromium in a group of healthy individuals with type 2 diabetes and to monitor the effect of daily supplementation with high chromium yeast on glucose tolerance, plasma insulin and lipoproteins. Twelve free-living adults with type 2 diabetes underwent a glucose tolerance test (GTT) on recruitment, at 4 weeks (after a 7-d duplicate diet collection) and at 12 weeks (following 8 weeks daily supplementation with 100 micrograms of chromium). Urine samples were collected on the day before and the day of each GTT. Blood samples were taken at half hourly intervals for 3 hours during the GTT and the plasma glucose, cholesterol, triglyceride, HDL, LDL and insulin concentration measured. The chromium content of diets and urine samples was determined. Fasting glucose concentrations and glucose area under the curve profiles did not alter significantly post supplementation with the chromium rich yeast. No significant changes in insulin and lipoprotein concentrations were observed. The results of this study do not support the hypothesis that individuals with type 2 diabetes benefit from yeast-based chromium supplements (100 micrograms/day).