31 No. 5
Trace Elements in Food
by Francesco Cubadda
Diet is the main source of trace elements and exposure to dietary trace elements has a direct impact on the health of hundreds of millions worldwide. Insufficient intake of essential trace elements is a global issue. The deficiencies of iron, zinc, iodine, and selenium result in millions of people being affected by various diseases, with very serious consequences in those countries where malnutrition is widespread. On the other hand, the impact of toxic element species, such as inorganic arsenic and methylmercury, on whole populations has come to the fore again as a priority for both the scientific community and health authorities.
The different facets of trace elements, from essentiality to toxicity, were addressed at the 3rd International Symposium on Trace Elements in Food (TEF-3). The meeting was held 1–3 April 2009 in Rome, Italy, organized by the Istituto Superiore di Sanità (ISS), and consisted of two and one-half days of oral and poster presentations. Like the two previous meetings in this series, organized in Warsaw, Poland (2000), and in Brussels, Belgium (2004), TEF-3 was held under the auspices of IUPAC.
Francesco Cubadda opens
The objective of this interdisciplinary symposium was to gather experts with different backgrounds to discuss all aspects of trace elements in food in relation to human health, with special emphasis on the biological effects of elements. The topics covered included essentiality, toxicity, bioaccessibility, bioavailability, speciation, sources and transfer in the food chain, effects of processing, food and feed fortification, supplementation, international legislation and standards, analytical developments, analytical quality assurance, and reference materials.
Over 200 participants, representing some 40 countries, joined the event. In addition to the 15 invited lectures, delegates from Europe, Asia, Africa, and North and South America enriched the program with 20 oral and about 130 poster contributions.
The symposium was opened by Francesco Cubadda (symposium chair), Agostino Macrì (director of the Department of Food Safety and Veterinary Public Health at ISS), and Ryszard Lobinski (past president of the IUPAC Analytical Chemistry Division), who served as the IUPAC representative. The scientific program was organized in four sessions, summarized below.
Advances in Trace Element Analysis in Food Matrices
(Chairs: Kevin Francesconi and Ryszard Lobinski)
The chairs of the first session: Kevin Francesconi (left) and Ryszard Lobinski.
Joanna Szpunar reviewed state-of-the-art analytical techniques for element speciation studies in food and food supplements. Szpunar discussed advantages and drawbacks of the currently used analytical approaches, with a focus on selenium. Erik H. Larsen dealt with the detection and characterization of inorganic nanoparticles in life science studies. Larsen discussed the merits of field flow fractionation, coupled with multi-angle light scattering detection, for size determination and for use with on-line inductively coupled plasma mass spectrometry (ICP-MS). Alfredo Sanz-Medel addressed speciation and isotope pattern deconvolution (IPD) for ICP-MS quantitative studies of minerals metabolism and supplementation, showing how the multi-spike IPD approach can be used to differentiate and quantitate endogenous (natural) and exogenous (supplemented) elemental species.
A series of lectures dealt with recent developments in the speciation of iodine (Jose Luis Gomez-Ariza), of selenium (John Entwisle and Mihaly Dernovics), and of different metals in wine (Krystyna Pyrzynska). The isotopic and elemental fingerprints used to prove the authenticity and origin of food and feed were addressed by Thomas Prohaska.
Finally, analytical quality in the determination of trace elements was discussed in regard to internal and external quality control procedures (Maria Beatriz de la Calle) and the reliability of published analytical data (Lars Jorhem).
At the end of this oral session, as with the other four, the chairs led a 15-minute plenary discussion with the aim of condensing the session’s core message. The main focus was on summarizing the state of the art based on the lectures, and also on trying to identify future challenges and subjects of research. The audience actively took part in the plenary discussions.
Sources and Transfer of Trace Elements
in the Food Chain
(Chairs: Alberto Mantovani and Barbara Szteke)
A lively discussion during the poster session.
The session featured a series of interesting contributions on selenium, beginning with the invited lecture of Margaret Rayman that dealt with food chain selenium and human health, highlighting the complexity of optimal intake. Selenium uptake, bioaccessibility, and speciation were discussed in connection with plant (Anicke Brandt-Kjelsen and Darren Juniper) and animal (Qiuhui Hu and Espen Govasmark) farming.
In the second part of this session, biofortification of iron in genetically engineered rice (Christof Sautter) and of zinc through application of fertilizers (Ismail Cakmak) were treated. Finally, the effect of repeated annual applications of phosphorus fertilizers on the phytoavailability of cadmium was addressed (Cynthia Grant).
Toxicology and Risk Assessment
(Chairs: Philippe Grandjean and Erik H. Larsen)
The pitfalls in assessing the adverse health effects of methylmercury in seafood were discussed by Philippe Grandjean, whereas Marie Vahter treated the gender differences in susceptibility to cadmium in food.
The emerging topic of nanosized materials and nanotoxicology was addressed by Chunying Chen, who reviewed the application of nanotechnology in the food industry and the toxicological issues surrounding nanomaterials.
Arsenic speciation and toxicology were addressed in relation to seafood (Kevin Francesconi) and rice (Jörg Feldmann). The metabolism of metal(loid)s by intestinal microorganisms was discussed by Roland Diaz-Bone, who showed how gut bacteria are able to modulate metal(loid) speciation, bioaccessibility, and toxicity. He also described the identification of a number of species, including mixed Se/S, As/S as well as As/Se compounds through the use of GC with both EI-MS and ICP-MS detection. The intestinal absorption of the arsenic species with higher toxicity, as studied by in vitro methods, was also dealt with (Vicenta Devesa).
Finally, the assessment of the risks and benefits of organic forms of trace elements as feed additives (Alberto Mantovani) and the effect of in vitro lead administration on porcine ovarian granulosa (Adriana Kolesarova) were discussed.
Trace Elements in Nutrition and Human Health
(Chairs: Marina Patriarca and Munehiro Yoshida)
The invited lecture of Bo Lönnerdal addressed the alternative pathways for iron absorption from food, and focused especially on ferritin. This iron-binding protein is present in meat, but also in low concentrations in a wide variety of plants (e.g., legumes), and it is possible to enhance the ferritin content of plants by conventional breeding or genetic engineering, and thereby increase the iron intake of populations consuming predominantly plant-based diets.
Susan Fairweather-Tait reported on the results of a human intervention study designed to establish the effect of selenium supplementation on selenium biomarkers and immune function. Ian J. Griffin reviewed the insights on trace mineral metabolism in children gained through stable isotopes studies. It was shown that fractional absorption is the main site of mineral homeostasis for some minerals (Ca, Mg) and faecal excretion is the main regulated site for others (Zn), and that the current Estimated Average Intakes for Ca and Zn may be too low for one- to four-year old children. The current perspectives on sustainable solutions to zinc deficiency in infants and young children were discussed by Nancy F. Krebs. Zinc in relation to metallothioneins and longevity was also addressed (Francesco Piacenza).
Other prominent topics of this session included the use of stable isotopes in in vivo studies by IPD-HPLC-ICP-MS (Maria Luisa Fernández-Sánchez), in vitro methods for assessing element bioaccessibility as influenced by breadmaking (Carmen Frontela), and the biomonitoring of iodine in the U.S. population by the U.S. Centers for Disease Control (Kathleen Caldwell).
Poster Sessions and Concluding Remarks
The wealth of material covered at the poster sessions was remarkable.1 Among many significant contributions, three works were selected for the poster awards. Katrin Löschner, Véronique Vacchina, and Tejo Prakash Nagaraja were awarded prizes for the posters entitled “AFFF-MALS-ICP-MS and Electron Microscopy for the Characterization of Nanoparticles in Biological Studies” (Löschner et al.), “Determination of Selenomethionine and Selenocysteine in Edible Tissues of Animal Origin” (Bierla et al.), and “Total Selenium and Selenium Speciation in Food Crops from a Seleniferous Area of Punjab” (Cubadda et al.), respectively.
Overall, TEF-3 resulted in a lively interdisciplinary symposium where research and development efforts and emerging issues in the area of trace elements in food were thoroughly discussed in a enjoyable atmosphere. The success of this edition led to the decision to held TEF-4 in three years, most likely outside Europe.
- F. Cubadda, F. Aureli, S. Ciardullo, M. Patriarca (Eds.). 2009. 3rd International IUPAC Symposium on Trace Elements in Food: Abstract Book. ISTISAN Congressi 09/C2, pp 207 (downloadable from www.iss.it).
Francesco Cubadda <[email protected]> is a research chemist at the Istituto Superiore di Sanità (ISS), the Italian National Health Institute.
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