Biol Trace Elem Res (2009) 127:228–233 DOI 10.1007/s12011-008-8245-1
Zinc and Selenium Nutritional Status in Vegetarians Maritsa Carla de Bortoli & Silvia Maria Franciscato Cozzolino
Received: 16 July 2008 / Accepted: 17 September 2008 / Published online: 25 October 2008 # Humana Press Inc. 2008
Abstract A vegetarian diet may have beneficial effects on human health, however when it is not well-balanced may be deficient in some nutrients, as minerals for example. The aim of the present study was to assess the nutritional status of zinc and selenium in vegetarians in the city of São Paulo. A cross-sectional study was performed, and the inclusion criteria were age ≥ 18 years, both gender, no use of food or pharmaceutical supplements. Thirty vegetarian, of both genders, mean age of 27 years and 4,5 years of vegetarianism had performed the study, and their mean BMI was 21,5. Zinc plasma concentration was 71 and 62,5 μg/dL for men and women and erythrocyte concentration was 37 μg/gHb for both genders. Selenium concentration was 73,5 and 77,3 μg/L in plasma and 51,4 and 66,9 μg/L in erythrocytes for men and women, respectively. These biochemical values show that, according to the references, selenium blood levels are adequate and zinc concentration in erythrocytes is deficient in the studied population. For this reason, vegetarians should be constantly assessed and receive nutritional support to reduce the effects of inadequate zinc status. Keywords Zinc . Selenium . Vegetarians . Nutritional status
Introduction It is believed that the vegetarian diet has beneficial effects on human health, however when it is not well-balanced, with excessive or deficient quantities of nutrients may have adverse consequences [1, 2]. Among the nutrients that may be at risk for deficiency in the
M. C. de Bortoli (*) PRONUT (Program of Applied Human Nutrition)–FSP/FCF/FEA, University of São Paulo, São Paulo, Brazil e-mail:
[email protected] M. C. de Bortoli : S. M. F. Cozzolino Lineu Prestes Avenue, 580-B14, Butantã–University City, São Paulo 05508-900, Brazil S. M. F. Cozzolino Faculty of Pharmaceutical Sciences, Department of Food and Experimental Nutrition, University of São Paulo, São Paulo, Brazil
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vegetarian diet we can cite microminerals that represent a small fraction of the diet, but have an important role in different metabolic processes [3]. Animal food sources may provide a variety of micronutrients that are hardly obtained in safe quantities from the vegetal food sources, and even though vegetarian diet may have similar quantity of trace elements than does the omnivore one, the bioavailability of these nutrients may be compromised by several different factors. Between the minerals that may be at concern about this diet are zinc and selenium [4–6], once zinc intake is usually matchable to omnivore diets but has lower bioavailability, and selenium ingestion is variable according to soil concentrations on the mineral [7]. Zinc acts like a structure and cell components stabilizer, and protecting cell integrity by preventing lipid peroxidation and diminishing free radical development. This mineral can decrease the oxidation susceptibility to thiol and lipoprotein groups and promote the removal of the free radicals [8–10]. Selenium is of fundamental importance for human health as a component of selenoproteins, in structural and enzymatic roles, as an antioxidant and catalytic for the production of active thyroid hormone. A higher intake may be associated to lower risks of cancer [11]. Knowing these minerals importance and their feasible risk in the vegetarian diet, the aim of this work was to assess zinc and selenium nutritional status in vegetarians.
Subjects and Methods Objective and Study Design A cross-sectional study was conducted to assess in vegetarians both zinc and selenium status and lifestyle characteristics. The present work was reviewed and approved by the Faculty of Pharmaceutical Sciences Ethics Committee of the University of São Paulo. Subjects Participants were recruited in Yoga schools, allowing this way the homogeneity between the subjects according to physical activity and philosophy for vegetarianism. Volunteers answered a questionnaire about life habits, including food choice, and were submitted to inclusion criteria (both genders; age >18 years; no use of food or pharmaceutical supplements; apparently healthy; not pregnant or nursing). All of those who were elected to the study were informed of the procedures and signed an informed consent form. Anthropometric Assessment Anthropometric assessment consisted of measurement of weight and height and the calculation of the body mass index (BMI). Collection and Handling of Blood Samples About 20 mL of fasting blood sample was collected. Sodium Citrate at 30% was used as anticoagulant for zinc (100 μL/10 mL blood) and EDTA (1 mg/mL) as anticoagulant for selenium. Blood was separated in plasma and erythrocytes [12], both components were packet in demineralized microtubes, and stored in −80°C until analysis.
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Analytic Methods Zinc concentrations were determined by flame atomic absorption spectrophotometry (spectrophotometer HITACHI Z-5000) in plasma [13] and erythrocyte ([12], modified by [14]). For the erythrocytes analysis, hemoglobin concentration was determined by its conversion to cyanmethemoglobin (Spectrophotometer HITACH, U1100) [15]. Selenium plasma and erythrocyte were determined by electrothermal atomic absorption spectroscopy [16] (SIMAA-6000), and the samples were diluted directly in the autosampler cut (AS-72). Methods reproducibility was achieved by triplicated sample and double reading, and validity was performed with Bovine Liver® and Seronorm Whole Blood® standards and standards Tritisol® addition in several concentrations. Methodological control was achieved using reagents of analytical purity. The water used for solutions and dilutions was Milli-Q®. Statistical Analysis Average, median, standard deviation, coefficient of variation, and minimum and maximum values were calculated. Student’s t-test was used to assess statistical significance between zinc or selenium blood concentration and their respective reference values (significance at P
