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Quantitative determination of selenium in the most common food items sold in Egypt

Quantitative determination of selenium in the most common food items sold in Egypt Particular interest in selenium (Se) was generated as a result of clinical studies showing that balanced Se dietary system is very important for many physiological processes. There is no recent information available on the Se content in Egyptian foods. The present study was conducted to measure Se content in different food groups. A cross-sectional study was designed; a total of 87 food items were randomly purchased from the main markets and hypermarkets in Alexandria governorate, then digested by wet ashing procedure and finally analyzed using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The highest mean Se value was obtained in protein-rich food followed by nuts and sweetened products (6.8, 6.2, and 5.89 μg/g respectively) shrimps had the highest value among all studied samples (6.8 μg/g), while the lowest one was in soft cheese (0.0036 μg/g). Selenium content in food groups is strongly correlated with food matrix and composition of food items, soil composition, and fortification process. Keywords: Selenium, Food samples, Egypt 1 Introduction certain skin infections [4]. Selenium acts as antioxidant, The impact of dieting on human health has received anti-inflammatory, antimutagenic, anticarcinogenic, anti- such a great care in the last few years with the under- viral, antibacterial, antimycotic, and antiparasitic. A re- standing that unbalanced or deficient diet can cause ser- cent study revealed that asthmatic patients have lower ious health problems. Three syndromes are associated level of Se in their blood compared to healthy popula- with Se deficiency: Keshan disease, osteoarthropathy tion [5]. In addition, Se may slow advancement of HIV syndrome, and Kashin-Beck disease [1, 2]. Selenium is disease by decreasing oxidative stress and inhibits viral an extremely important trace element of both nutritional cytotoxic effects [6]. There are at least 30 Se dependent and toxicological interest. Selenium content in food is proteins that act as a cofactor in order to convert thy- widely different depending on its concentration in the roxine (T4) to bioactive (T3) including glutathione per- soil in a given geographical area, the ability of plants to oxidase and iodothyronine deiodinases enzymes [7]. accumulate it, as well as animal feed. Other components Epidemiological researches indicated that there is an in- such as cultivation, climatic conditions, breeding verse association between low Se level and prostate, lung, methods, and methods of preparing food products may and colorectal cancer. It was found that low selenium in- also have an effect on Se content in food [3]. take could accelerate the emergence of cancer cells. There Adequate intake of Se in diet reduces risk of heart dis- was a small positive association between blood serum Se eases and low-density lipoprotein (LDL) level in blood, levels and cancer mortality that highlights the potential improves immune function, maintains thyroid function, application of selenium in cancer prevention and treat- activates synthesis of deoxyribinucleotide, and prevents ment especially among smokers. Also, an association was found between blood Se level and depression, kidney dis- * Correspondence: samaraborhyem@yahoo.com ease, thyroid dysfunction, Alzheimer, liver fibrosis, acute Department of Nutrition, High institute of Public Health, Alexandria watery diarrhea, and fertility [8, 9]. University, Alexandria, Egypt Full list of author information is available at the end of the article © The Author(s). 2020 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. Moatkhef et al. Journal of the Egyptian Public Health Association (2020) 95:15 Page 2 of 9 Excess Se intake may result in many health problems sausage, sussis, bastrama, veal meat, cow’s kidney, beef, [10–12]. High Se intake in individuals without proved sheep meat, and cow’s liver), fruits and vegetables (beet, deficit may have bad effects such as hyper-glycaemia, cucumber, apple, garlic, lemon, tomato, onion, orange, hyper-lipidemia, and depression. Selenium toxicity has carrot, and banana), protein-rich food (beans, lentils, been observed after consumption of a large (250 mg) sin- egg, chicken, mackerel, mullet, tilapia, duck, crab, and gle dose or after multiple doses [13, 14]. shrimps), nuts (cashew, seed sunflower, watermelon Symptoms of high Se intake are strong garlic-like odor, seed, peanuts, pistachio, almond, hazelnut, walnut, and nausea, vomiting, diarrhea, fatigue, skin lesions, de- sesame seeds), fats (industrial butter, morta, industrial creased cognitive function, weakness, hyperreflexia, pain margarine, animal fat, coconut oil, sunflower oil, corn in the extremities; or paralysis, tremor, muscle spasms, oil, olive oil, local margarine, and local butter), and restlessness, confusion, delirium, coma, mucosal damage sweetened products(gelatine, tea biscuits, jam, galaxy to the oral cavity, esophagus, and finally death [1, 2]. chocolate, raw chocolate, chocolate biscuits, sweet tahini, Selenium compounds are generally very efficiently black honey, and bee honey). Nine food items were absorbed by humans; selenium absorption does not taken from each of the beverages, sweetened products, appear to be under homeostatic control. For example, and nuts, while 10 food items were taken from each of absorption of the selenite form of selenium is greater the remaining groups giving the total of 87. Each food than 80%, whereas that of selenium as selenomethio- item was purchased four times from four different mar- nine or as selenate may be greater than 90%. There- kets in Alexandria governorate giving a total of 348 sam- fore, the rate-limiting step determining the overall ples. Pooling was done for each food item (four availability of dietary selenium is not likely to be its replicates) by mixing them well together to obtain ran- absorption but rather its conversion within tissues to dom and representative sample for each. Samples were its metabolically active forms (e.g., its incorporation collected during the period of January–March 2018. into GSHPx or 5-deiodinase) [15]. Selenium is a biologically important element for 2.2 Sample storage humans. Different food groups are considered the main Samples were collected and protected from contamin- sources of Se. It is worthy to know that Se should be ation or Se loss during analysis. Samples as meat, fish, taken in specific quantities without increasing or de- and seafood were stored at − 20 °C till analysis. Yogurt, creasing in order to maintain human health. Unfortu- fruit vegetable, and cheese were analyzed once pur- nately in many countries all over the world, human food chased, while in case of other food items as oil, nuts, ingredients do not provide sufficient Se [16]. In addition, cereal, and beverages they were stored at room the data concerning selenium content in food compos- temperature 27 °C until analysis. ition tables is often poor and depends on whether ana- lysis is up to date and to what extent natural variability 2.3 Sample preparation in selenium content is considered. Currently, there is no Solid samples (cereal, legume, and nuts) were grained available data concerning selenium intake among Egyp- by grinder, while liquid samples were analyzed dir- tians [9, 10]. Lack of data about selenium content in ectly. Fresh milk and dairy products were collected in Egyptian foods may be one of plausible explanations as a special container to avoid contamination. Fats and selenium is not included in the Egyptian food compos- connective tissue were discarded from meat and ition tables; therefore, the present study was conducted poultry, whilein case of seafoodonlyedibleparts of to determine the content of Se in different food groups, tissue were analyzed; head, skin, viscera, scales, and in order to facilitate the formal decision about dietary tail were removed. Edible portions of vegetables and selenium intake among Egyptians. fruits were homogenized well in a porcelain mortar to obtain homogeneous samples [17]. 2 Materials and methods 2.1 Sample collection 2.4 Methods Study included the nine studied food groups: beverages All samples were prepared for selenium analysis by wet (cola, nescafe, tea, mint, carob, ginger, roselle, caraway, ashing procedure [18]. Sample preparation by wet ashing and fenugreek), carbohydrate rich food (toast, shami was categorized according to methods of digestion. Food bread, sweet potato, vino bread, macaroni with whole samples were divided into the following: grain, rice, pasta, potato, local bread, and corn), milk Beverages: 100 mg of each sample was added to 10 ml and its product (soft cheese, skimmed milk, processed of HNO (65%), heated on hotplate at 130 °C till dry- cheese, fat-free yogurt, semi-hard cheese, roomy cheese, ness. After cooling, 5 ml of H O (40%) was added and 2 2 raw milk, full-cream milk, full-cream yogurt, and local reheated at 130 °C again till dryness. Samples were di- yogurt) meat and its products (luncheon meat, kufta, luted with 20-ml distilled water and filtered twice Moatkhef et al. Journal of the Egyptian Public Health Association (2020) 95:15 Page 3 of 9 through Whatman filter paper grade II to glass bottles. interference effects from polyatomic ions and doubly Milk samples: two steps were operated. First step, 2.5 ml charged ions. In all experiments, a relative standard devi- of milk samples was added to 4 ml of nitric acid (65%), ation (RSD) of 3% was achieved. To obtain precise and and 4 ml of hydrogen peroxide (40%) and 4 ml of dis- accurate results, element signals were monitored by real- tilled water were added, then heated at 200 °C till dry- time display (RTD), which showed the constant sensitivity ness. Second step, addition of 1.4 ml of HCl, then heated over time for the selected masses and the ratios of masses at 100 °C, after cooling; 2 ml of H SO was added and with three readings, calculated for each sample [2]. 2 4 heated at 50 °C then increase temperature to 130 °C till dryness. Samples were diluted and filtrated. Concerning 2.5.4 ICP-MS analysis dairy products: 1 g was weighted then added 10 ml of The diluted solution was filtered through a plastic tube concentrated nitric acid (65%), heated at 100 °C. Then designed for the autosampler of Agilent 4500 Series 10 ml of hydrogen peroxide (40%) was added and heated ICP-MS (Agilent, Palo Alto, CA, USA) that was used for again at120 °C; finally, 2 ml of HCl was added and the analysis of selenium content. The analysis conditions heated at 200 °C till dryness. were as follows: RF power 1200 W, plasma gas (Ar) 16.0 Meat and seafood:1 g of each sample type was ml/min, aux. gas (Ar) 1.0 ml/min, carrier gas (Ar) 1.14 weighted and 15 ml HNO3 (65%) was added then heated ml/min, Barbington-type nebulizer, glass spray chamber, at 200 °C. After cooling, 15 ml of H O was added, and sampling depth 8.2 mm, Ni/Ni sampling cone/skimmer 2 2 then heated at 150 °C. While in case of cereal, legume, cone, and mass for selenium was m/z 82. Selenium con- and nuts samples, 1 g was added to 20ml nitric acid centrations of the samples were calculated from the re- (65%), 20 ml of hydrogen peroxide, and 20-ml distilled gression line (r = 0.999) obtained using selenium water, and then heated at 170 °C till dryness. Vegetables standard solution (Wako Pure Chemical Industries, and fruits: 1 g of sample was added to 10 ml of the Osaka, Japan) [19]. HNO (65%). Samples were kept overnight at the room The method was validated by analysis of selenium con- temperature, then heated at 100 °C. After cooling, 5 ml tent of NIST Standard Reference Material 8436 durum of HCl was added and heated till dryness. Sweetened wheat flour obtained from National Institute of Stan- products and liquid fat samples: 5 ml of sample was dards and Technology (Boulder, CO, USA), and the re- added to 5.0 ml of HNO and heated at 100 °C till dry- covery tests were performed on some food groups ness. All the wet-digested samples were ready to deter- spiked with selenium standard and the recovery value mine Se content by Inductively Coupled Plasma-Mass ranged (0.002–0.05 μg/g) [19]. Spectrometry, USA. (Varian 720-ES) [17]. 2.6 Statistical analysis of the data 2.5 ICP-MS determination procedure Data were fed to the computer and analyzed using the 2.5.1 Instrumentation IBM SPSS software package version 20.0. (Armonk, NY: ICP-MS measurements were performed using a VG IBM Corp.). Qualitative data were described using number Plasma Qua Ex-Cell (Thermo, Courtaboeuf, France). and percent. The Kolmogorov-Smirnov test was used to Sample solutions were pumped by a peristaltic pump verify the normality of distribution. Quantitative data were from tubes arranged on a CETAC Varian 720-ES In- described using range (minimum and maximum), mean, ductively Coupled Plasma-Mass-Spectrometry USA standard deviation, and median. Significance of the ob- (CETAC, Omaha, NE) [2]. tained results was judged at the 5% level. The used tests were Kruskal–Wallis test for abnormally distributed quan- 2.5.2 Optimization titative variables, to compare between more than two The isotope 78Se, 82Se was selected as analytical masses studied groups and post hoc (Dunn’s multiple compari- in ICP-MS instrumental parameters. sons test) for pairwise comparisons [19, 20]. 2.5.3 Operating conditions 3 Results and discussion Nebulizer: concentric type pumped at 0.9 ml/min. Spray Despite the fact that fruits contain low levels of Se be- chamber: Scott-type double-pass water cooled. ICP-MS cause of its high water and low protein content [21], the standard mode for Se elements, several specific isotopes present study revealed that the value of Se in banana, or- were considered and monitored according to the sensi- ange, and apple was 2.3, 1.3, and 0.84 μg/g respectively tivity of the element and/or possible isobaric and poly- as shown in Table 1. This may be attributed to agricul- atomic interferences. Torch position, ion lenses, and gas tural activities that may influence Se levels in foodstuffs, output were optimized daily with the tuning solution (1 where Se has been added to fertilizers in some areas of g/l) to carry out a short-term stability test on the instru- the world in order to increase Se levels in cultivated ment, to maximize ion signals, and to minimize plants and indirectly improve Se status in humans. In Moatkhef et al. Journal of the Egyptian Public Health Association (2020) 95:15 Page 4 of 9 Table 1 Selenium content in various foods (μg/g) Beverages Mean ± S.D Nuts Mean ± S.D Sweetened products Mean ± S.D Sample (μg/g) Sample (μg/g) Sample (μg/g) a a Cola drink 0.002 ± 0.001 0.69 ± 1.44 Cashew 0.028 ± 0.013 2.29 ± 1.94 Gelatin 0.001 ± 0.001 1.56 ±1.92 Instant coffee 0.005 ± 0.001 Seed sunflower 0.51 ± 0.01 Tea biscuits 0.26 ± 0.18 Tea 0.0064 ± 0.001 Watermelon seeds 0.96 ± 0.21 Jam 0.35 ± 0.22 Mint 0.014 ± 0.005 Peanuts 2.14 ± 0.51 Galaxy 0.62 ± 0.47 Carob 0.018 ± 0.010 Pistachio 2.24 ± 0.68 Raw chocolate 0.94 ± 0.17 Ginger 0.028 ± 0.013 Almonds 3.25 ± 0.29 Chocolate biscuits 1.61 ± 0.59 Roselle 0.35 ± 0.12 Hazelnut 3.56 ± 0.33 Sweet tahini 2.36 ± 0.83 Caraway 2.20 ± 0.26 Walnuts 4.22 ± 0.10 Black honey 3.10 ± 0.15 Fenugreek 4.30 ± 0.70 Sesame seeds 5.89 ± 0.84 Bee honey 6.20 ± 0.62 Carbohydrate-rich Mean ± S.D Protein-rich foods Mean ± S.D Fat Mean ± S.D food Sample (μg/g) Sample (μg/g) Sample (μg/g) b ad a Toast 0.014 ± 0.011 0.36 ± 0.64 Bean 0.26 ± 0.047 3.07 ± 2.17 Industrial butter 0.0033 ± 0.002 1.74 ±1.86 Shami bread 0.023 ± 0.021 Lentils 0.42 ± 0.326 Morta 0.026 ± 0.038 Sweet potato 0.028 ± 0.003 Eggs 1.42 ± 0.556 Industrial margarine 0.041 ± 0.036 Vino bread 0.045 ± 0.017 Poultry 2.2 ± 0.588 Animal fat 0.12 ± 0.10 Macaroni with 0.11 ± 0.098 Mackerel 2.4 ± 0.448 Coconut oil 0.26 ± 0.12 whole grain Rice 0.15 ± 0.03 Mullet 3.9 ± 0.826 Sunflower oil 1.8 ± 0.04 Pasta 0.16 ± 0.04 Tilapia 3.30 ± 0.394 Corn oil 3.2 ± 0.61 Potatoes 0.48 ± 0.41 Ducks 4.2 ± 0.471 Olive oil 3.4 ± 0.69 Local bread 0.48 ± 0.41 Crab 5.8 ± 0.850 Local margarine 4.1 ± 0.85 Corn 2.1 ± 0.46 Shrimp 6.8 ± 0.035 Local butter 4.4 ± 0.14 Vegetables and Mean ± S.D Meat and its Mean ± S.D Milk and dairy products Mean ± S.D fruits products Sample (μg/g) Sample (μg/g) Sample (μg/g) e e Beet 0.024 ± 0.028 1.06 ± 0.68 Luncheon meat 0.001 ± 0.001 1.03 ± 1.22 Soft cheese 0.0036 ± 0.002 0.82 ± 0.93 Cucumber 0.032 ± 0.019 Kufta 0.0022 ± 0.002 Skimmed milk 0.023 ± 0.015 Apple 0.84 ± 0.021 Sausage 0.0084 ± 0.013 Cheese triangular 0.025 ± 0.022 Garlic 0.98 ± 0.357 Sussis (sausage) 0.023 ± 0.020 Free-fat yogurt 0.096 ± 0.006 Lemon 1.1 ± 0.80 Bastrama 0.52 ± 0.21 Semi-hard cheese 0.47 ± 0.08 Tomatoes 1.1 ± 0.40 Veal meat 0.64 ± 0.56 Rumi cheese 0.68 ± 0.18 Moatkhef et al. Journal of the Egyptian Public Health Association (2020) 95:15 Page 5 of 9 Table 1 Selenium content in various foods (μg/g) (Continued) Onions 1.3 ± 0.24 Cow’s kidney 1.48 ± 0.70 Raw milk 0.94 ± 0.05 Orange 1.3 ± 0.32 Beef 1.8 ± 0.07 Full-cream milk 1.25 ± 0.13 Carrots 1.6 ± 0.28 Sheep meat 2.2 ± 0.38 Full-cream yogurt 2.12 ± 0.36 Banana 2.3 ± 0.20 Cow’s liver 3.62 ± 0.71 Local yogurt 2.63 ± 0.31 Significant with drinks group Significant with nuts group Significant with sweetened group Significant with carbohydrate group Significant with protein-rich foods group Moatkhef et al. Journal of the Egyptian Public Health Association (2020) 95:15 Page 6 of 9 comparison to other studies, Se content in the present honeys were ranging from < 0.01 to 0.11 mg/g. This dif- study was higher than that given for fruits grown or pur- ference may be due to the influence of the geographical chased in eastern Croatia [22]. Meanwhile, Klapec et al. and botanical origin of the honeys. Prevalence of the dif- [22] results came in agreement with current results in ferent melliferous flowers and trees harvested by bees is descending order of selenium in fruits where Se values influenced by the soil composition in addition to the cli- in banana, orange, and apple were 0.203, 0.076, and matic conditions and difference in bees species. 0.088 μg/g, respectively. Concerning Se content in Egyptian rice, corn, and There is a remarkable increase in Se value in Egyptian local bread, it was found that Se values were 0.15, 2.1, fenugreek (4.3 μg/g) (Table 1). This value is not in agree- and 0.48 μg/g respectively as presented in Table 1. These ment with other researchers. Askar and Bielig [17]stated values were higher than those obtained by Choi et al. that Se content of Egyptian fenugreek was 0.29 μg/g; Kar- [19] who found that Se values in Korean rice, corn, and adas [23] stated that content of Se in fenugreek was zero, loaf bread were 0.050, < 0.001, and 0.216 μg/g, succes- and Al-Ahmary [24] stated that Se content in Saudi Ara- sively. Meanwhile, Se value in macaroni with whole grain bia’s fenugreek seeds was 0.022 μg/g. This may be attrib- 0.11 μg/g, versus buck wheat noodles in Choi et al. [19] uted to enrichment of Egyptian soil with minerals [25]. who demonstrated similar 0.110 μg/g Se value with the Regarding selenium content in nuts, it was found that ses- present study. ame seeds had the highest Se value 5.89 μg/g as presented in Results concerning Se content in rice was 0.15 μg/g, Table 1, and this finding is contradicted with Askar and Bie- which was higher than results in Saudi Arabia 0.072 μg/g lig [17] who stated that, sesame seeds revealed much lower [24], in Brazil 0.13 μg/g [26], as well as in Thailand Se content 0.38 μg/g, that maybedueto Askar study was 0.05 μg/g [30]. On the other hand, it was lower than that done in 1983, and also due to more sophisticated and ad- recorded in a Greek study 0.191 μg/g. This may be due vanced instrument was used in the present study. to the difference of selenium content in soils from one Lemire et al. [26] showed that Brazilian walnuts had country to another one [31, 32]. higher Se content than that detected in the present study Table 2 shows that protein-rich food contained the 4.22 μg/g. This confirms the theory of Brazilian walnuts highest mean Se 3.07 μg/g ± 2.17 compared to the rest are rich in Se content. These differences may be due to eight groups followed by nuts 2.29 μg/g ± 1.94 then fat geographical, climatologic differences which possibly re- group 1.74 μg/g ± 1.86, while food rich in carbohydrate flect differences in Se concentration in soil all over the had the lowest mean of Se 0.36 μg/g ± 0.64. There was a world [27, 28]. significant difference in Se content among the nine stud- Data concerning bee and black honey were 6.2 and ied groups (P < 0.005). 3.1 μg/g respectively as shown in Table 1. These findings Selenium content in fish is highly variable and depends are higher than Se value in the study of Costa-Silva et al. not only on fish species, but also on fish habitat and sea- [29] who stated that Se content of Portuguese unifloral son (Table 1)[33]. This statement came in line with the Table 2 Comparison between the nine studied groups according to selenium content (μg/g) Groups N Selenium content (μg/g) H p Min.–Max. Mean ± SD. Median * * Drinks 10 0.0–4.30 0.69 ± 1.44 0.02 21.808 0.005 Nuts 10 0.03–5.89 2.29 ± 1.94 2.19 Sweetened products 10 0.0–6.20 1.56 ± 1.92 0.78 Carbohydrate 10 0.01–2.10 0.36 ± 0.64 0.13 ad Protein-rich foods 10 0.26–6.80 3.07 ± 2.17 2.85 Fat 10 0.0–4.40 1.74 ± 1.86 1.03 Vegetables and fruits 10 0.02–2.30 1.06 ± 0.68 1.10 Meat 10 0.0–3.62 1.03 ± 1.22 0.58 Milk and dairy products 10 0.0–2.63 0.82 ± 0.93 0.58 H Kruskal–Wallis test pp value for comparing between the nine groups *Statistically significant at p ≤ 0.05 Significant with drinks group Significant with nuts group Significant with sweetened group Significant with carbohydrate group Significant with protein-rich foods group Moatkhef et al. Journal of the Egyptian Public Health Association (2020) 95:15 Page 7 of 9 present study, were mullet and tilapia had the highest Se selenium; possibly enriched animal feed and raw mate- content among other food items (3.9 and 3.30 μg/g re- rials of olive oil, corn oil, and local margarine are rich spectively) as shown in Table 1. Se content of Mediterra- with minerals. nean sea-fish in Alexandria had high levels compared with Results of the present study as regards garlic and the fish from tropical Brazilian coast. Seixas et al. [34] onion demonstrated that Se content was 0.98 and who reported that high Se content was found in both car- 1.3 μg/g respectively. These results highlighted that Al- nivorous and non-carnivorous fish (1.63 and 1.08 μg/g re- lium genus (onion, garlic) tends to accumulate Se prob- spectively). Se content in fish is high and that may be due ably because of their greater fraction of sulfur- to high protein content in fish. Fish can be in some cases containing amino acids [21], where adequate analogs of a poor source of available Se, due to its high content of these can be formed by substitution of sulfur with Se, mercury (Hg) and other heavy metals, which bind to Se resulting in high Se levels. These results were higher forming insoluble inorganic complexes [35]. Choi et al. than those reported by Askar and Bielig [17] in Egypt [19] in Korea revealed lower Se contents in shellfish and who found that Se values in garlic and onion were 0.52 their products ranging from 0.152 to 0.788 μg/g, when and 0.02 μg/g respectively. Choi et al. [19] in Korea re- compared with the present results. Seixas et al. [34]stated ported that, onions and garlic had 0.052 and 0.021 μg/g, that Se content in shrimp was 1.08 μg/g, and it is consid- respectively. Lemire et al. [26] in Brazil revealed lower ered lower than the present results (6.8 μg/g) that may be Se values in garlic and onion, 0.08 and 0.07 μg/g, re- due to difference in fish habitat and season [28]. spectively. It is known that garlic and onion tend to have Foods of animal origin are assumed to contain high higher Se concentrations. level of Se because selenium is an essential element for Results concerning Se content in beef meat were 1.8 μg/ the growth of animals [22]. This statement is in agree- g; this finding highlighted that Egyptian meat beef is a ment with the present results where Se value in eggs good source of Se, due to its high protein and mineral was 1.42 μg/g (Table 1). Fortunately, the present study contents. Data of the present study was higher than values exhibited higher Se value than the study of Yaroshenko reported in Yu et al's study [39] about Se geochemical dis- et al. [36] in eggs, which was 0.194 μg/g. Choi et al. [19] tribution in the environment and predicted human daily in Korea revealed that Se content in eggs was 0.267 μg/g; dietary intake which had reported higher soil concentra- Lemire et al. [26] also found that eggs (yolks and white) tions of Se. Furthermore, Choi et al. [19]reported that, had Se values 0.56 and 0.21 μg/g, respectively. Gao et al. meats had a range of 0.043–0.324 μg/g. These differences [37] reported that Se content in eggs in China was in Se concentration of meat products possibly reflect dif- 0.152 μg/g. Elevated results concerning eggs may be as a ferences in the Se concentration of the animals feed, result of enriched animal feed in Egypt [38]. where selenium is supplied in the animal diet either in Selenium content in various fat revealed that Se in natural organic form (mainly selenomethionine) or in the olive oil, corn oil, local margarine, and local butter were inorganic form (sodium selenite or selenate). Moreover, 3.4, 3.2, 4.1, and 4.4 μg/g respectively. These findings difference of Se concentrations in soil worldwide plays im- were much higher than that in Al-Ahmary [24] in Saudi portant role as well [33, 40]. Arabia, who found that Se values in olive oil, corn oil, Selenium values in raw milk, full cream milk, as well margarine, and butter were 0.002, 0.007, 0.002, and as skimmed milk were 0.94, 1.25, and 0.023 μg/g respect- 0.005 μg/g, respectively. Local products were rich in ively. These results are not expected because it is known Table 3 Significance and non-significance of differences between nine studied groups according to selenium content Groups Beverages Nuts Sweetened product Carbohydrate Protein-rich foods Fat Vegetables Meat Milk and milk and fruits products * * * * Beverages 0.003 0.048 0.697 < 0.001 0.044 0.055 0.281 0.260 Nuts 0.338 0.011 0.475 0.353 0.306 0.063 0.070 Sweetened 0.111 0.094 0.976 0.949 0.366 0.392 Carbohydrate 0.001 0.105 0.127 0.491 0.462 * * Protein-rich foods 0.100 0.082 0.010 0.011 Fat 0.925 0.351 0.376 Vegetables and fruits 0.402 0.428 Meat 0.962 Milk and dairy products The p value for Dunn’s multiple comparison test comparing between each two groups *Statistically significant at p ≤ 0.05 Moatkhef et al. Journal of the Egyptian Public Health Association (2020) 95:15 Page 8 of 9 that Se concentration in milk is negatively correlated Funding There was not any funding agency for this research. with its fat content. These findings are not in accordance with what was found in other studies [14, 26, 30]. Selen- Availability of data and materials ium ratio in milk may be lower than meat and egg due The data are available from the corresponding author on reasonable request. to the fact that milk contains less protein than meat and Ethics approval and consent to participate egg. Approval of the Ethics Committee of the High Institute of Public Health was th Results concerning local yogurt and full-cream yogurt obtained in 17 January 2018. The study carried out in compliance with the International Guidelines for Research Ethics. Consent to Participate is not were 2.63 and 2.12 μg/g respectively, while in free-fat applicable. yogurt, Se value was 0.096 μg/g. These findings are not in agreement with literature which highlighted that Se Consent for publication concentration in milk is negatively correlated with its fat Not applicable. content [26]. They were also higher than what found in Competing interests other studies; Pappa et al. [31] (2006) in Greek who The authors declare that they have no competing interests. stated reported that Se content was 0.02 μg in full- or Author details low-fat yoghurt compared to 0.03 μg/g in free fat one 1 2 Al-Thawra General Hospital, Al-Hadidiya, Yemen. Department of Nutrition, [31]. Choi et al. [19] in Korea reported that yoghurt had High institute of Public Health, Alexandria University, Alexandria, Egypt. 0.011 μg/g of Se. That may be due to different methods Received: 22 October 2019 Accepted: 5 June 2020 in preparing raw materials during yoghurt processing and also may be due to the presence of powdered milk in our yoghurt products. References On comparing the significance between the nine stud- 1. Grotto D, Carneiro MFH, de Castro MM, Garcia SC, Junior FB. Long-term excessive selenium supplementation induces hypertension in rats. Biol Trace ied food groups shown in Table 3, we found that there Element Res. 2018;182(1):70–7. was a significant difference between the majority of 2. Noël L, Chekri R, Millour S, Vastel C, Kadar A, Sirot V, et al. Li, Cr, Mn, Co, Ni, groups (p < 0.05), while there was a strong significant Cu, Zn, Se and Mo levels in foodstuffs from the Second French TDS. Food Chem. 2012;132(3):1502–13. difference between the following pairs: drinks versus 3. Ivory K, Nicoletti C. Selenium is a source of aliment and ailment: do we protein-rich foods and carbohydrate-rich foods versus need more? Trends Food Sci Technol. 2017;62:190–3. protein-rich foods as p < 0.001. 4. Leonard K. The association of selenium levels with markers of cardiovascular disease. [Dissertation]. USA: University of Pittsburgh; 2016. 5. Shi L, Ren Y, Zhang C, Yue W, Lei F. Effects of organic selenium (Se-enriched 4 Conclusions and recommendations yeast) supplementation in gestation diet on antioxidant status, hormone profile and haemato-biochemical parameters in Taihang Black Goats. Anim Protein rich foods had the highest sources of Se in Egyp- Feed Sci Technol. 2018;238:57–65. tian products, followed by nuts. On the other hand, soft- 6. Notsek M, Gorchakova N, Belenichev I, Puzyrenko A, Chekman I. drinks and milk products represented the lowest sources Nanoselenium and selenium: role in the body and application in medical practice. Ukrainian Sci Med Youth J. 2015;4(91):129–33. of Se. Generally, the richest sources of Se in the Egyptian 7. Schloss J. Cancer treatment and nutritional deficiencies. In: Erkekoǧlu P, diet were bee honey, fenugreek, sesame, local margarine editor. Nutritional deficiency: InTech. 2016;173–96. https://www.intechopen. and butter, ducks, fish, and olive oil. Meanwhile, some com/books/nutritional-deficiency/cancer-treatment-and-nutritional- deficiencies. foods contained lower proportion of Se but consumed in 8. Franca C, Nogueira C, Ramalho A, Carvalho A, Vieira S, Penna A. Serum large quantities such as carbohydrate, vegetables, and levels of selenium in patients with breast cancer before and after treatment fruits, as well as milk and milk products. There are no of external beam radiotherapy. Ann Oncol. 2010;22(5):1109–12. 9. Deng FE, Shivappa N, Tang Y, Mann JR, Hebert JR. Association between concerns about the expectation of Se deficiency among diet-related inflammation, all-cause, all-cancer, and cardiovascular disease Egyptians since no estimation of dietary reference intake mortality, with special focus on prediabetics: findings from NHANES III. Eur J was performed. The researchers recommend further study Nutr. 2017;56(3):1085–93. 10. Otieno SB. Selenium an essential micronutrient for human health. EC to cover the other unstudied Egyptian food samples. Nutrition. 2017;7:261–3. 11. Wang Y, Lin M, Gao X, Pedram P, Du J, Vikram C, et al. High dietary Acknowledgements selenium intake is associated with less insulin resistance in the Authors are grateful to thank laboratories’ manager in Holding Company of Newfoundland population. PloS one. 2017;12(4):e0174149. Water and Sanitation in Cairo for facilitating the analysis of samples using 12. Rocourt CR, Cheng W-H. Selenium supranutrition: are the potential benefits ICP-MS. of chemoprevention outweighed by the promotion of diabetes and insulin resistance? Nutrients. 2013;5(4):1349–65. Authors’ contributions 13. Silva VM, Boleta EHM, Lanza MGDB, Lavres J, Martins JT, Santos EF, et al. FM was responsible for the major contribution of this work including; Physiological, biochemical, and ultrastructural characterization of selenium sampling, laboratory work, statistical part, interpretation of data, and helped toxicity in cowpea plants. Environ Exp Botany. 2018;150:172–82. in preparation of research paper. HI was responsible for supervising the 14. Morris JS, Crane SB. Selenium toxicity from a misformulated dietary interpretation of final data. NA was responsible for analyzing and supervising supplement, adverse health effects, and the temporal response in the nail laboratory work and supervising data interpretation. SA guided the biologic monitor. Nutrients. 2013;5(4):1024–57. researcher in choosing the research point, guided the student in all the 15. Greger JL, Smith SA, Snedeker SM. Effect of dietary calcium and phosphorus stages of the research and wrote the research paper. All authors read and levels on the utilization of calcium, phosphorus, magnesium, manganese, approved the final manuscript. and selenium by adult males. Nutr Res. 1981;1(4):315–25. Moatkhef et al. Journal of the Egyptian Public Health Association (2020) 95:15 Page 9 of 9 16. Toth RJ, Csapo J. The role of selenium in nutrition: a review. Acta Univ Publisher’sNote Sapient Alimentar. 2018;11(2):128. Springer Nature remains neutral with regard to jurisdictional claims in 17. Askar A, Bielig HJ. Selenium content of food consumed by Egyptians. Food published maps and institutional affiliations. Chem. 1983;10(3):231–4. 18. Adamczyk-Szabela D, Anielak P, Wolf WM. Influence of digestion procedure and residual carbon on manganese, copper, and zinc determination in herbal matrices by atomic absorption spectrometry. J Analytical Methods Chem. 2017;2017:6947376. 19. Choi Y, Kim J, Lee HS, Kim C, Hwang IK, Park HK, et al. Selenium content in representative Korean foods. J Food Compost Anal. 2009;22(2):117–22. 20. Kirkpatrick LA, Feeney BC. A simple guide to IBM SPSS statistics for version 20.0. Student ed. Belmont, Calif.: Wadsworth, Cengage Learning. 2013. 21. Şlencu B, Ciobanu C, Cuciureanu R. Selenium content in foodstuffs and its nutritional requirement for humans. Clujul Med. 2012;85(2):139–45. 22. Klapec T, Mandić ML, Grgić J, Primorac L, Perl A, Krstanović V. Selenium in selected foods grown or purchased in eastern Croatia. Food Chem. 2004; 85(3):445–52. 23. Karadas F. Scientific data on selenium status in Turkey. Agricl Sci. 2014;5(2): 87–93. 24. Al-Ahmary KM. Selenium content in selected foods from the Saudi Arabia market and estimation of the daily intake. Arabian J Chem. 2009;2(2):95–9. 25. McNeal JM, Balistrieri LS. Geochemistry and occurrence of selenium: an overview. In: Jacobs LW, editor. Selenium in agriculture and the environment. Madison, Wisconsin: SSSA Special Publication; 1989. 26. Lemire M, Fillion M, Barbosa F Jr, Guimaraes JR, Mergler D. Elevated levels of selenium in the typical diet of Amazonian riverside populations. Sci Total Environ. 2010;408(19):4076–84. 27. Saha U, Fayiga A, Sonon L. Selenium in the soil-plant environment: a review. Int J Appl Agric Sci. 2017;3(1):1–18. 28. Shaheen SM, Frohne T, White JR, DeLaune RD, Rinklebe J. Redox-induced mobilization of copper, selenium, and zinc in deltaic soils originating from Mississippi (U.S.A.) and Nile (Egypt) River Deltas: a better understanding of biogeochemical processes for safe environmental management. J Environ Manage. 2017;186(Pt 2):131–40. 29. Costa-Silva F, Maia M, Matos CC, Calçada E, Barros AIRNA, Nunes FM. Selenium content of Portuguese unifloral honeys. J Food Compos Anal. 2011;24(3):351–5. 30. Sirichakwal PP, Puwastien P, Polngam J, Kongkachuichai R. Selenium content of Thai foods. J Food Compost Anal. 2005;18(1):47–59. 31. Pappa EC, Pappas AC, Surai PF. Selenium content in selected foods from the Greek market and estimation of the daily intake. Sci Total Environ. 2006; 372(1):100–8. 32. Favorito JE. An investigation into selenium geochemistry in phosphate mine soils. [Doctoral Dissertations]. Faculty of the Virginia Polytechnic Institute and State University; 2017. 33. dos Santos M, da Silva Júnior FMR, Muccillo-Baisch AL. Selenium content of Brazilian foods: a review of the literature values. J Food Compost Anal. 2017; 58:10–5. 34. Seixas TG, Moreira I, Malm O, Kehrig HA. Mercury and selenium in a top- predator fish, Trichiurus lepturus (Linnaeus, 1758), from the tropical Brazilian Coast, Rio de Janeiro. Bull Environ Contam Toxicol. 2012;89(2):434–8. 35. Johnston JN, Savage GP. Mercury consumption and toxicity with reference to fish and fish meal. Nutr Abstr Rev. 1991;61:73–116. 36. Yaroshenko FA, Dvorsaka YE, Surai P, Sparks NH. Selenium-enriched eggs as a source of selenium for human consumption. Food Sci Policy. 2003;1:13–23. 37. Gao Y, Walder K, Sunderland T, Kantham L, Feng HC, Quick M, et al. Elevation in Tanis expression alters glucose metabolism and insulin sensitivity in H4IIE cells. Diabetes. 2003;52(4):929–34. 38. European Food Safety Authority (EFSA) Panel on Additives Products or Substances used in Animal Feed. Safety and efficacy of selenium compounds (E8) as feed additives for all animal species: sodium selenite, based on a dossier submitted by Todini and Co SpA. EFSA Journal. 2016; 14(3):4442. 39. Yu D, Liang D, Lei L, Zhang R, Sun X, Lin Z. Selenium geochemical distribution in the environment and predicted human daily dietary intake in northeastern Qinghai. China. Environ Sci Pollut Res Int. 2015;22(15):11224–35. 40. Fairweather-Tait SJ, Bao Y, Broadley MR, Collings R, Ford D, Hesketh JE, et al. Selenium in human health and disease. Antioxid Redox Signal. 2011;14(7): 1337–83. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of the Egyptian Public Health Association Springer Journals

Quantitative determination of selenium in the most common food items sold in Egypt

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Springer Journals
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10.1186/s42506-020-00044-z
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Abstract

Particular interest in selenium (Se) was generated as a result of clinical studies showing that balanced Se dietary system is very important for many physiological processes. There is no recent information available on the Se content in Egyptian foods. The present study was conducted to measure Se content in different food groups. A cross-sectional study was designed; a total of 87 food items were randomly purchased from the main markets and hypermarkets in Alexandria governorate, then digested by wet ashing procedure and finally analyzed using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The highest mean Se value was obtained in protein-rich food followed by nuts and sweetened products (6.8, 6.2, and 5.89 μg/g respectively) shrimps had the highest value among all studied samples (6.8 μg/g), while the lowest one was in soft cheese (0.0036 μg/g). Selenium content in food groups is strongly correlated with food matrix and composition of food items, soil composition, and fortification process. Keywords: Selenium, Food samples, Egypt 1 Introduction certain skin infections [4]. Selenium acts as antioxidant, The impact of dieting on human health has received anti-inflammatory, antimutagenic, anticarcinogenic, anti- such a great care in the last few years with the under- viral, antibacterial, antimycotic, and antiparasitic. A re- standing that unbalanced or deficient diet can cause ser- cent study revealed that asthmatic patients have lower ious health problems. Three syndromes are associated level of Se in their blood compared to healthy popula- with Se deficiency: Keshan disease, osteoarthropathy tion [5]. In addition, Se may slow advancement of HIV syndrome, and Kashin-Beck disease [1, 2]. Selenium is disease by decreasing oxidative stress and inhibits viral an extremely important trace element of both nutritional cytotoxic effects [6]. There are at least 30 Se dependent and toxicological interest. Selenium content in food is proteins that act as a cofactor in order to convert thy- widely different depending on its concentration in the roxine (T4) to bioactive (T3) including glutathione per- soil in a given geographical area, the ability of plants to oxidase and iodothyronine deiodinases enzymes [7]. accumulate it, as well as animal feed. Other components Epidemiological researches indicated that there is an in- such as cultivation, climatic conditions, breeding verse association between low Se level and prostate, lung, methods, and methods of preparing food products may and colorectal cancer. It was found that low selenium in- also have an effect on Se content in food [3]. take could accelerate the emergence of cancer cells. There Adequate intake of Se in diet reduces risk of heart dis- was a small positive association between blood serum Se eases and low-density lipoprotein (LDL) level in blood, levels and cancer mortality that highlights the potential improves immune function, maintains thyroid function, application of selenium in cancer prevention and treat- activates synthesis of deoxyribinucleotide, and prevents ment especially among smokers. Also, an association was found between blood Se level and depression, kidney dis- * Correspondence: samaraborhyem@yahoo.com ease, thyroid dysfunction, Alzheimer, liver fibrosis, acute Department of Nutrition, High institute of Public Health, Alexandria watery diarrhea, and fertility [8, 9]. University, Alexandria, Egypt Full list of author information is available at the end of the article © The Author(s). 2020 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. Moatkhef et al. Journal of the Egyptian Public Health Association (2020) 95:15 Page 2 of 9 Excess Se intake may result in many health problems sausage, sussis, bastrama, veal meat, cow’s kidney, beef, [10–12]. High Se intake in individuals without proved sheep meat, and cow’s liver), fruits and vegetables (beet, deficit may have bad effects such as hyper-glycaemia, cucumber, apple, garlic, lemon, tomato, onion, orange, hyper-lipidemia, and depression. Selenium toxicity has carrot, and banana), protein-rich food (beans, lentils, been observed after consumption of a large (250 mg) sin- egg, chicken, mackerel, mullet, tilapia, duck, crab, and gle dose or after multiple doses [13, 14]. shrimps), nuts (cashew, seed sunflower, watermelon Symptoms of high Se intake are strong garlic-like odor, seed, peanuts, pistachio, almond, hazelnut, walnut, and nausea, vomiting, diarrhea, fatigue, skin lesions, de- sesame seeds), fats (industrial butter, morta, industrial creased cognitive function, weakness, hyperreflexia, pain margarine, animal fat, coconut oil, sunflower oil, corn in the extremities; or paralysis, tremor, muscle spasms, oil, olive oil, local margarine, and local butter), and restlessness, confusion, delirium, coma, mucosal damage sweetened products(gelatine, tea biscuits, jam, galaxy to the oral cavity, esophagus, and finally death [1, 2]. chocolate, raw chocolate, chocolate biscuits, sweet tahini, Selenium compounds are generally very efficiently black honey, and bee honey). Nine food items were absorbed by humans; selenium absorption does not taken from each of the beverages, sweetened products, appear to be under homeostatic control. For example, and nuts, while 10 food items were taken from each of absorption of the selenite form of selenium is greater the remaining groups giving the total of 87. Each food than 80%, whereas that of selenium as selenomethio- item was purchased four times from four different mar- nine or as selenate may be greater than 90%. There- kets in Alexandria governorate giving a total of 348 sam- fore, the rate-limiting step determining the overall ples. Pooling was done for each food item (four availability of dietary selenium is not likely to be its replicates) by mixing them well together to obtain ran- absorption but rather its conversion within tissues to dom and representative sample for each. Samples were its metabolically active forms (e.g., its incorporation collected during the period of January–March 2018. into GSHPx or 5-deiodinase) [15]. Selenium is a biologically important element for 2.2 Sample storage humans. Different food groups are considered the main Samples were collected and protected from contamin- sources of Se. It is worthy to know that Se should be ation or Se loss during analysis. Samples as meat, fish, taken in specific quantities without increasing or de- and seafood were stored at − 20 °C till analysis. Yogurt, creasing in order to maintain human health. Unfortu- fruit vegetable, and cheese were analyzed once pur- nately in many countries all over the world, human food chased, while in case of other food items as oil, nuts, ingredients do not provide sufficient Se [16]. In addition, cereal, and beverages they were stored at room the data concerning selenium content in food compos- temperature 27 °C until analysis. ition tables is often poor and depends on whether ana- lysis is up to date and to what extent natural variability 2.3 Sample preparation in selenium content is considered. Currently, there is no Solid samples (cereal, legume, and nuts) were grained available data concerning selenium intake among Egyp- by grinder, while liquid samples were analyzed dir- tians [9, 10]. Lack of data about selenium content in ectly. Fresh milk and dairy products were collected in Egyptian foods may be one of plausible explanations as a special container to avoid contamination. Fats and selenium is not included in the Egyptian food compos- connective tissue were discarded from meat and ition tables; therefore, the present study was conducted poultry, whilein case of seafoodonlyedibleparts of to determine the content of Se in different food groups, tissue were analyzed; head, skin, viscera, scales, and in order to facilitate the formal decision about dietary tail were removed. Edible portions of vegetables and selenium intake among Egyptians. fruits were homogenized well in a porcelain mortar to obtain homogeneous samples [17]. 2 Materials and methods 2.1 Sample collection 2.4 Methods Study included the nine studied food groups: beverages All samples were prepared for selenium analysis by wet (cola, nescafe, tea, mint, carob, ginger, roselle, caraway, ashing procedure [18]. Sample preparation by wet ashing and fenugreek), carbohydrate rich food (toast, shami was categorized according to methods of digestion. Food bread, sweet potato, vino bread, macaroni with whole samples were divided into the following: grain, rice, pasta, potato, local bread, and corn), milk Beverages: 100 mg of each sample was added to 10 ml and its product (soft cheese, skimmed milk, processed of HNO (65%), heated on hotplate at 130 °C till dry- cheese, fat-free yogurt, semi-hard cheese, roomy cheese, ness. After cooling, 5 ml of H O (40%) was added and 2 2 raw milk, full-cream milk, full-cream yogurt, and local reheated at 130 °C again till dryness. Samples were di- yogurt) meat and its products (luncheon meat, kufta, luted with 20-ml distilled water and filtered twice Moatkhef et al. Journal of the Egyptian Public Health Association (2020) 95:15 Page 3 of 9 through Whatman filter paper grade II to glass bottles. interference effects from polyatomic ions and doubly Milk samples: two steps were operated. First step, 2.5 ml charged ions. In all experiments, a relative standard devi- of milk samples was added to 4 ml of nitric acid (65%), ation (RSD) of 3% was achieved. To obtain precise and and 4 ml of hydrogen peroxide (40%) and 4 ml of dis- accurate results, element signals were monitored by real- tilled water were added, then heated at 200 °C till dry- time display (RTD), which showed the constant sensitivity ness. Second step, addition of 1.4 ml of HCl, then heated over time for the selected masses and the ratios of masses at 100 °C, after cooling; 2 ml of H SO was added and with three readings, calculated for each sample [2]. 2 4 heated at 50 °C then increase temperature to 130 °C till dryness. Samples were diluted and filtrated. Concerning 2.5.4 ICP-MS analysis dairy products: 1 g was weighted then added 10 ml of The diluted solution was filtered through a plastic tube concentrated nitric acid (65%), heated at 100 °C. Then designed for the autosampler of Agilent 4500 Series 10 ml of hydrogen peroxide (40%) was added and heated ICP-MS (Agilent, Palo Alto, CA, USA) that was used for again at120 °C; finally, 2 ml of HCl was added and the analysis of selenium content. The analysis conditions heated at 200 °C till dryness. were as follows: RF power 1200 W, plasma gas (Ar) 16.0 Meat and seafood:1 g of each sample type was ml/min, aux. gas (Ar) 1.0 ml/min, carrier gas (Ar) 1.14 weighted and 15 ml HNO3 (65%) was added then heated ml/min, Barbington-type nebulizer, glass spray chamber, at 200 °C. After cooling, 15 ml of H O was added, and sampling depth 8.2 mm, Ni/Ni sampling cone/skimmer 2 2 then heated at 150 °C. While in case of cereal, legume, cone, and mass for selenium was m/z 82. Selenium con- and nuts samples, 1 g was added to 20ml nitric acid centrations of the samples were calculated from the re- (65%), 20 ml of hydrogen peroxide, and 20-ml distilled gression line (r = 0.999) obtained using selenium water, and then heated at 170 °C till dryness. Vegetables standard solution (Wako Pure Chemical Industries, and fruits: 1 g of sample was added to 10 ml of the Osaka, Japan) [19]. HNO (65%). Samples were kept overnight at the room The method was validated by analysis of selenium con- temperature, then heated at 100 °C. After cooling, 5 ml tent of NIST Standard Reference Material 8436 durum of HCl was added and heated till dryness. Sweetened wheat flour obtained from National Institute of Stan- products and liquid fat samples: 5 ml of sample was dards and Technology (Boulder, CO, USA), and the re- added to 5.0 ml of HNO and heated at 100 °C till dry- covery tests were performed on some food groups ness. All the wet-digested samples were ready to deter- spiked with selenium standard and the recovery value mine Se content by Inductively Coupled Plasma-Mass ranged (0.002–0.05 μg/g) [19]. Spectrometry, USA. (Varian 720-ES) [17]. 2.6 Statistical analysis of the data 2.5 ICP-MS determination procedure Data were fed to the computer and analyzed using the 2.5.1 Instrumentation IBM SPSS software package version 20.0. (Armonk, NY: ICP-MS measurements were performed using a VG IBM Corp.). Qualitative data were described using number Plasma Qua Ex-Cell (Thermo, Courtaboeuf, France). and percent. The Kolmogorov-Smirnov test was used to Sample solutions were pumped by a peristaltic pump verify the normality of distribution. Quantitative data were from tubes arranged on a CETAC Varian 720-ES In- described using range (minimum and maximum), mean, ductively Coupled Plasma-Mass-Spectrometry USA standard deviation, and median. Significance of the ob- (CETAC, Omaha, NE) [2]. tained results was judged at the 5% level. The used tests were Kruskal–Wallis test for abnormally distributed quan- 2.5.2 Optimization titative variables, to compare between more than two The isotope 78Se, 82Se was selected as analytical masses studied groups and post hoc (Dunn’s multiple compari- in ICP-MS instrumental parameters. sons test) for pairwise comparisons [19, 20]. 2.5.3 Operating conditions 3 Results and discussion Nebulizer: concentric type pumped at 0.9 ml/min. Spray Despite the fact that fruits contain low levels of Se be- chamber: Scott-type double-pass water cooled. ICP-MS cause of its high water and low protein content [21], the standard mode for Se elements, several specific isotopes present study revealed that the value of Se in banana, or- were considered and monitored according to the sensi- ange, and apple was 2.3, 1.3, and 0.84 μg/g respectively tivity of the element and/or possible isobaric and poly- as shown in Table 1. This may be attributed to agricul- atomic interferences. Torch position, ion lenses, and gas tural activities that may influence Se levels in foodstuffs, output were optimized daily with the tuning solution (1 where Se has been added to fertilizers in some areas of g/l) to carry out a short-term stability test on the instru- the world in order to increase Se levels in cultivated ment, to maximize ion signals, and to minimize plants and indirectly improve Se status in humans. In Moatkhef et al. Journal of the Egyptian Public Health Association (2020) 95:15 Page 4 of 9 Table 1 Selenium content in various foods (μg/g) Beverages Mean ± S.D Nuts Mean ± S.D Sweetened products Mean ± S.D Sample (μg/g) Sample (μg/g) Sample (μg/g) a a Cola drink 0.002 ± 0.001 0.69 ± 1.44 Cashew 0.028 ± 0.013 2.29 ± 1.94 Gelatin 0.001 ± 0.001 1.56 ±1.92 Instant coffee 0.005 ± 0.001 Seed sunflower 0.51 ± 0.01 Tea biscuits 0.26 ± 0.18 Tea 0.0064 ± 0.001 Watermelon seeds 0.96 ± 0.21 Jam 0.35 ± 0.22 Mint 0.014 ± 0.005 Peanuts 2.14 ± 0.51 Galaxy 0.62 ± 0.47 Carob 0.018 ± 0.010 Pistachio 2.24 ± 0.68 Raw chocolate 0.94 ± 0.17 Ginger 0.028 ± 0.013 Almonds 3.25 ± 0.29 Chocolate biscuits 1.61 ± 0.59 Roselle 0.35 ± 0.12 Hazelnut 3.56 ± 0.33 Sweet tahini 2.36 ± 0.83 Caraway 2.20 ± 0.26 Walnuts 4.22 ± 0.10 Black honey 3.10 ± 0.15 Fenugreek 4.30 ± 0.70 Sesame seeds 5.89 ± 0.84 Bee honey 6.20 ± 0.62 Carbohydrate-rich Mean ± S.D Protein-rich foods Mean ± S.D Fat Mean ± S.D food Sample (μg/g) Sample (μg/g) Sample (μg/g) b ad a Toast 0.014 ± 0.011 0.36 ± 0.64 Bean 0.26 ± 0.047 3.07 ± 2.17 Industrial butter 0.0033 ± 0.002 1.74 ±1.86 Shami bread 0.023 ± 0.021 Lentils 0.42 ± 0.326 Morta 0.026 ± 0.038 Sweet potato 0.028 ± 0.003 Eggs 1.42 ± 0.556 Industrial margarine 0.041 ± 0.036 Vino bread 0.045 ± 0.017 Poultry 2.2 ± 0.588 Animal fat 0.12 ± 0.10 Macaroni with 0.11 ± 0.098 Mackerel 2.4 ± 0.448 Coconut oil 0.26 ± 0.12 whole grain Rice 0.15 ± 0.03 Mullet 3.9 ± 0.826 Sunflower oil 1.8 ± 0.04 Pasta 0.16 ± 0.04 Tilapia 3.30 ± 0.394 Corn oil 3.2 ± 0.61 Potatoes 0.48 ± 0.41 Ducks 4.2 ± 0.471 Olive oil 3.4 ± 0.69 Local bread 0.48 ± 0.41 Crab 5.8 ± 0.850 Local margarine 4.1 ± 0.85 Corn 2.1 ± 0.46 Shrimp 6.8 ± 0.035 Local butter 4.4 ± 0.14 Vegetables and Mean ± S.D Meat and its Mean ± S.D Milk and dairy products Mean ± S.D fruits products Sample (μg/g) Sample (μg/g) Sample (μg/g) e e Beet 0.024 ± 0.028 1.06 ± 0.68 Luncheon meat 0.001 ± 0.001 1.03 ± 1.22 Soft cheese 0.0036 ± 0.002 0.82 ± 0.93 Cucumber 0.032 ± 0.019 Kufta 0.0022 ± 0.002 Skimmed milk 0.023 ± 0.015 Apple 0.84 ± 0.021 Sausage 0.0084 ± 0.013 Cheese triangular 0.025 ± 0.022 Garlic 0.98 ± 0.357 Sussis (sausage) 0.023 ± 0.020 Free-fat yogurt 0.096 ± 0.006 Lemon 1.1 ± 0.80 Bastrama 0.52 ± 0.21 Semi-hard cheese 0.47 ± 0.08 Tomatoes 1.1 ± 0.40 Veal meat 0.64 ± 0.56 Rumi cheese 0.68 ± 0.18 Moatkhef et al. Journal of the Egyptian Public Health Association (2020) 95:15 Page 5 of 9 Table 1 Selenium content in various foods (μg/g) (Continued) Onions 1.3 ± 0.24 Cow’s kidney 1.48 ± 0.70 Raw milk 0.94 ± 0.05 Orange 1.3 ± 0.32 Beef 1.8 ± 0.07 Full-cream milk 1.25 ± 0.13 Carrots 1.6 ± 0.28 Sheep meat 2.2 ± 0.38 Full-cream yogurt 2.12 ± 0.36 Banana 2.3 ± 0.20 Cow’s liver 3.62 ± 0.71 Local yogurt 2.63 ± 0.31 Significant with drinks group Significant with nuts group Significant with sweetened group Significant with carbohydrate group Significant with protein-rich foods group Moatkhef et al. Journal of the Egyptian Public Health Association (2020) 95:15 Page 6 of 9 comparison to other studies, Se content in the present honeys were ranging from < 0.01 to 0.11 mg/g. This dif- study was higher than that given for fruits grown or pur- ference may be due to the influence of the geographical chased in eastern Croatia [22]. Meanwhile, Klapec et al. and botanical origin of the honeys. Prevalence of the dif- [22] results came in agreement with current results in ferent melliferous flowers and trees harvested by bees is descending order of selenium in fruits where Se values influenced by the soil composition in addition to the cli- in banana, orange, and apple were 0.203, 0.076, and matic conditions and difference in bees species. 0.088 μg/g, respectively. Concerning Se content in Egyptian rice, corn, and There is a remarkable increase in Se value in Egyptian local bread, it was found that Se values were 0.15, 2.1, fenugreek (4.3 μg/g) (Table 1). This value is not in agree- and 0.48 μg/g respectively as presented in Table 1. These ment with other researchers. Askar and Bielig [17]stated values were higher than those obtained by Choi et al. that Se content of Egyptian fenugreek was 0.29 μg/g; Kar- [19] who found that Se values in Korean rice, corn, and adas [23] stated that content of Se in fenugreek was zero, loaf bread were 0.050, < 0.001, and 0.216 μg/g, succes- and Al-Ahmary [24] stated that Se content in Saudi Ara- sively. Meanwhile, Se value in macaroni with whole grain bia’s fenugreek seeds was 0.022 μg/g. This may be attrib- 0.11 μg/g, versus buck wheat noodles in Choi et al. [19] uted to enrichment of Egyptian soil with minerals [25]. who demonstrated similar 0.110 μg/g Se value with the Regarding selenium content in nuts, it was found that ses- present study. ame seeds had the highest Se value 5.89 μg/g as presented in Results concerning Se content in rice was 0.15 μg/g, Table 1, and this finding is contradicted with Askar and Bie- which was higher than results in Saudi Arabia 0.072 μg/g lig [17] who stated that, sesame seeds revealed much lower [24], in Brazil 0.13 μg/g [26], as well as in Thailand Se content 0.38 μg/g, that maybedueto Askar study was 0.05 μg/g [30]. On the other hand, it was lower than that done in 1983, and also due to more sophisticated and ad- recorded in a Greek study 0.191 μg/g. This may be due vanced instrument was used in the present study. to the difference of selenium content in soils from one Lemire et al. [26] showed that Brazilian walnuts had country to another one [31, 32]. higher Se content than that detected in the present study Table 2 shows that protein-rich food contained the 4.22 μg/g. This confirms the theory of Brazilian walnuts highest mean Se 3.07 μg/g ± 2.17 compared to the rest are rich in Se content. These differences may be due to eight groups followed by nuts 2.29 μg/g ± 1.94 then fat geographical, climatologic differences which possibly re- group 1.74 μg/g ± 1.86, while food rich in carbohydrate flect differences in Se concentration in soil all over the had the lowest mean of Se 0.36 μg/g ± 0.64. There was a world [27, 28]. significant difference in Se content among the nine stud- Data concerning bee and black honey were 6.2 and ied groups (P < 0.005). 3.1 μg/g respectively as shown in Table 1. These findings Selenium content in fish is highly variable and depends are higher than Se value in the study of Costa-Silva et al. not only on fish species, but also on fish habitat and sea- [29] who stated that Se content of Portuguese unifloral son (Table 1)[33]. This statement came in line with the Table 2 Comparison between the nine studied groups according to selenium content (μg/g) Groups N Selenium content (μg/g) H p Min.–Max. Mean ± SD. Median * * Drinks 10 0.0–4.30 0.69 ± 1.44 0.02 21.808 0.005 Nuts 10 0.03–5.89 2.29 ± 1.94 2.19 Sweetened products 10 0.0–6.20 1.56 ± 1.92 0.78 Carbohydrate 10 0.01–2.10 0.36 ± 0.64 0.13 ad Protein-rich foods 10 0.26–6.80 3.07 ± 2.17 2.85 Fat 10 0.0–4.40 1.74 ± 1.86 1.03 Vegetables and fruits 10 0.02–2.30 1.06 ± 0.68 1.10 Meat 10 0.0–3.62 1.03 ± 1.22 0.58 Milk and dairy products 10 0.0–2.63 0.82 ± 0.93 0.58 H Kruskal–Wallis test pp value for comparing between the nine groups *Statistically significant at p ≤ 0.05 Significant with drinks group Significant with nuts group Significant with sweetened group Significant with carbohydrate group Significant with protein-rich foods group Moatkhef et al. Journal of the Egyptian Public Health Association (2020) 95:15 Page 7 of 9 present study, were mullet and tilapia had the highest Se selenium; possibly enriched animal feed and raw mate- content among other food items (3.9 and 3.30 μg/g re- rials of olive oil, corn oil, and local margarine are rich spectively) as shown in Table 1. Se content of Mediterra- with minerals. nean sea-fish in Alexandria had high levels compared with Results of the present study as regards garlic and the fish from tropical Brazilian coast. Seixas et al. [34] onion demonstrated that Se content was 0.98 and who reported that high Se content was found in both car- 1.3 μg/g respectively. These results highlighted that Al- nivorous and non-carnivorous fish (1.63 and 1.08 μg/g re- lium genus (onion, garlic) tends to accumulate Se prob- spectively). Se content in fish is high and that may be due ably because of their greater fraction of sulfur- to high protein content in fish. Fish can be in some cases containing amino acids [21], where adequate analogs of a poor source of available Se, due to its high content of these can be formed by substitution of sulfur with Se, mercury (Hg) and other heavy metals, which bind to Se resulting in high Se levels. These results were higher forming insoluble inorganic complexes [35]. Choi et al. than those reported by Askar and Bielig [17] in Egypt [19] in Korea revealed lower Se contents in shellfish and who found that Se values in garlic and onion were 0.52 their products ranging from 0.152 to 0.788 μg/g, when and 0.02 μg/g respectively. Choi et al. [19] in Korea re- compared with the present results. Seixas et al. [34]stated ported that, onions and garlic had 0.052 and 0.021 μg/g, that Se content in shrimp was 1.08 μg/g, and it is consid- respectively. Lemire et al. [26] in Brazil revealed lower ered lower than the present results (6.8 μg/g) that may be Se values in garlic and onion, 0.08 and 0.07 μg/g, re- due to difference in fish habitat and season [28]. spectively. It is known that garlic and onion tend to have Foods of animal origin are assumed to contain high higher Se concentrations. level of Se because selenium is an essential element for Results concerning Se content in beef meat were 1.8 μg/ the growth of animals [22]. This statement is in agree- g; this finding highlighted that Egyptian meat beef is a ment with the present results where Se value in eggs good source of Se, due to its high protein and mineral was 1.42 μg/g (Table 1). Fortunately, the present study contents. Data of the present study was higher than values exhibited higher Se value than the study of Yaroshenko reported in Yu et al's study [39] about Se geochemical dis- et al. [36] in eggs, which was 0.194 μg/g. Choi et al. [19] tribution in the environment and predicted human daily in Korea revealed that Se content in eggs was 0.267 μg/g; dietary intake which had reported higher soil concentra- Lemire et al. [26] also found that eggs (yolks and white) tions of Se. Furthermore, Choi et al. [19]reported that, had Se values 0.56 and 0.21 μg/g, respectively. Gao et al. meats had a range of 0.043–0.324 μg/g. These differences [37] reported that Se content in eggs in China was in Se concentration of meat products possibly reflect dif- 0.152 μg/g. Elevated results concerning eggs may be as a ferences in the Se concentration of the animals feed, result of enriched animal feed in Egypt [38]. where selenium is supplied in the animal diet either in Selenium content in various fat revealed that Se in natural organic form (mainly selenomethionine) or in the olive oil, corn oil, local margarine, and local butter were inorganic form (sodium selenite or selenate). Moreover, 3.4, 3.2, 4.1, and 4.4 μg/g respectively. These findings difference of Se concentrations in soil worldwide plays im- were much higher than that in Al-Ahmary [24] in Saudi portant role as well [33, 40]. Arabia, who found that Se values in olive oil, corn oil, Selenium values in raw milk, full cream milk, as well margarine, and butter were 0.002, 0.007, 0.002, and as skimmed milk were 0.94, 1.25, and 0.023 μg/g respect- 0.005 μg/g, respectively. Local products were rich in ively. These results are not expected because it is known Table 3 Significance and non-significance of differences between nine studied groups according to selenium content Groups Beverages Nuts Sweetened product Carbohydrate Protein-rich foods Fat Vegetables Meat Milk and milk and fruits products * * * * Beverages 0.003 0.048 0.697 < 0.001 0.044 0.055 0.281 0.260 Nuts 0.338 0.011 0.475 0.353 0.306 0.063 0.070 Sweetened 0.111 0.094 0.976 0.949 0.366 0.392 Carbohydrate 0.001 0.105 0.127 0.491 0.462 * * Protein-rich foods 0.100 0.082 0.010 0.011 Fat 0.925 0.351 0.376 Vegetables and fruits 0.402 0.428 Meat 0.962 Milk and dairy products The p value for Dunn’s multiple comparison test comparing between each two groups *Statistically significant at p ≤ 0.05 Moatkhef et al. Journal of the Egyptian Public Health Association (2020) 95:15 Page 8 of 9 that Se concentration in milk is negatively correlated Funding There was not any funding agency for this research. with its fat content. These findings are not in accordance with what was found in other studies [14, 26, 30]. Selen- Availability of data and materials ium ratio in milk may be lower than meat and egg due The data are available from the corresponding author on reasonable request. to the fact that milk contains less protein than meat and Ethics approval and consent to participate egg. Approval of the Ethics Committee of the High Institute of Public Health was th Results concerning local yogurt and full-cream yogurt obtained in 17 January 2018. The study carried out in compliance with the International Guidelines for Research Ethics. Consent to Participate is not were 2.63 and 2.12 μg/g respectively, while in free-fat applicable. yogurt, Se value was 0.096 μg/g. These findings are not in agreement with literature which highlighted that Se Consent for publication concentration in milk is negatively correlated with its fat Not applicable. content [26]. They were also higher than what found in Competing interests other studies; Pappa et al. [31] (2006) in Greek who The authors declare that they have no competing interests. stated reported that Se content was 0.02 μg in full- or Author details low-fat yoghurt compared to 0.03 μg/g in free fat one 1 2 Al-Thawra General Hospital, Al-Hadidiya, Yemen. Department of Nutrition, [31]. Choi et al. [19] in Korea reported that yoghurt had High institute of Public Health, Alexandria University, Alexandria, Egypt. 0.011 μg/g of Se. That may be due to different methods Received: 22 October 2019 Accepted: 5 June 2020 in preparing raw materials during yoghurt processing and also may be due to the presence of powdered milk in our yoghurt products. References On comparing the significance between the nine stud- 1. Grotto D, Carneiro MFH, de Castro MM, Garcia SC, Junior FB. Long-term excessive selenium supplementation induces hypertension in rats. Biol Trace ied food groups shown in Table 3, we found that there Element Res. 2018;182(1):70–7. was a significant difference between the majority of 2. Noël L, Chekri R, Millour S, Vastel C, Kadar A, Sirot V, et al. Li, Cr, Mn, Co, Ni, groups (p < 0.05), while there was a strong significant Cu, Zn, Se and Mo levels in foodstuffs from the Second French TDS. Food Chem. 2012;132(3):1502–13. difference between the following pairs: drinks versus 3. Ivory K, Nicoletti C. Selenium is a source of aliment and ailment: do we protein-rich foods and carbohydrate-rich foods versus need more? Trends Food Sci Technol. 2017;62:190–3. protein-rich foods as p < 0.001. 4. Leonard K. The association of selenium levels with markers of cardiovascular disease. [Dissertation]. USA: University of Pittsburgh; 2016. 5. Shi L, Ren Y, Zhang C, Yue W, Lei F. Effects of organic selenium (Se-enriched 4 Conclusions and recommendations yeast) supplementation in gestation diet on antioxidant status, hormone profile and haemato-biochemical parameters in Taihang Black Goats. Anim Protein rich foods had the highest sources of Se in Egyp- Feed Sci Technol. 2018;238:57–65. tian products, followed by nuts. On the other hand, soft- 6. Notsek M, Gorchakova N, Belenichev I, Puzyrenko A, Chekman I. drinks and milk products represented the lowest sources Nanoselenium and selenium: role in the body and application in medical practice. Ukrainian Sci Med Youth J. 2015;4(91):129–33. of Se. Generally, the richest sources of Se in the Egyptian 7. Schloss J. Cancer treatment and nutritional deficiencies. In: Erkekoǧlu P, diet were bee honey, fenugreek, sesame, local margarine editor. Nutritional deficiency: InTech. 2016;173–96. https://www.intechopen. and butter, ducks, fish, and olive oil. Meanwhile, some com/books/nutritional-deficiency/cancer-treatment-and-nutritional- deficiencies. foods contained lower proportion of Se but consumed in 8. Franca C, Nogueira C, Ramalho A, Carvalho A, Vieira S, Penna A. Serum large quantities such as carbohydrate, vegetables, and levels of selenium in patients with breast cancer before and after treatment fruits, as well as milk and milk products. There are no of external beam radiotherapy. Ann Oncol. 2010;22(5):1109–12. 9. Deng FE, Shivappa N, Tang Y, Mann JR, Hebert JR. Association between concerns about the expectation of Se deficiency among diet-related inflammation, all-cause, all-cancer, and cardiovascular disease Egyptians since no estimation of dietary reference intake mortality, with special focus on prediabetics: findings from NHANES III. Eur J was performed. The researchers recommend further study Nutr. 2017;56(3):1085–93. 10. Otieno SB. Selenium an essential micronutrient for human health. EC to cover the other unstudied Egyptian food samples. Nutrition. 2017;7:261–3. 11. Wang Y, Lin M, Gao X, Pedram P, Du J, Vikram C, et al. High dietary Acknowledgements selenium intake is associated with less insulin resistance in the Authors are grateful to thank laboratories’ manager in Holding Company of Newfoundland population. PloS one. 2017;12(4):e0174149. Water and Sanitation in Cairo for facilitating the analysis of samples using 12. Rocourt CR, Cheng W-H. Selenium supranutrition: are the potential benefits ICP-MS. of chemoprevention outweighed by the promotion of diabetes and insulin resistance? Nutrients. 2013;5(4):1349–65. Authors’ contributions 13. Silva VM, Boleta EHM, Lanza MGDB, Lavres J, Martins JT, Santos EF, et al. FM was responsible for the major contribution of this work including; Physiological, biochemical, and ultrastructural characterization of selenium sampling, laboratory work, statistical part, interpretation of data, and helped toxicity in cowpea plants. Environ Exp Botany. 2018;150:172–82. in preparation of research paper. HI was responsible for supervising the 14. Morris JS, Crane SB. Selenium toxicity from a misformulated dietary interpretation of final data. NA was responsible for analyzing and supervising supplement, adverse health effects, and the temporal response in the nail laboratory work and supervising data interpretation. SA guided the biologic monitor. Nutrients. 2013;5(4):1024–57. researcher in choosing the research point, guided the student in all the 15. Greger JL, Smith SA, Snedeker SM. Effect of dietary calcium and phosphorus stages of the research and wrote the research paper. All authors read and levels on the utilization of calcium, phosphorus, magnesium, manganese, approved the final manuscript. and selenium by adult males. Nutr Res. 1981;1(4):315–25. Moatkhef et al. Journal of the Egyptian Public Health Association (2020) 95:15 Page 9 of 9 16. Toth RJ, Csapo J. The role of selenium in nutrition: a review. Acta Univ Publisher’sNote Sapient Alimentar. 2018;11(2):128. Springer Nature remains neutral with regard to jurisdictional claims in 17. Askar A, Bielig HJ. Selenium content of food consumed by Egyptians. Food published maps and institutional affiliations. Chem. 1983;10(3):231–4. 18. Adamczyk-Szabela D, Anielak P, Wolf WM. Influence of digestion procedure and residual carbon on manganese, copper, and zinc determination in herbal matrices by atomic absorption spectrometry. J Analytical Methods Chem. 2017;2017:6947376. 19. Choi Y, Kim J, Lee HS, Kim C, Hwang IK, Park HK, et al. Selenium content in representative Korean foods. J Food Compost Anal. 2009;22(2):117–22. 20. Kirkpatrick LA, Feeney BC. A simple guide to IBM SPSS statistics for version 20.0. Student ed. Belmont, Calif.: Wadsworth, Cengage Learning. 2013. 21. Şlencu B, Ciobanu C, Cuciureanu R. Selenium content in foodstuffs and its nutritional requirement for humans. Clujul Med. 2012;85(2):139–45. 22. Klapec T, Mandić ML, Grgić J, Primorac L, Perl A, Krstanović V. Selenium in selected foods grown or purchased in eastern Croatia. Food Chem. 2004; 85(3):445–52. 23. Karadas F. Scientific data on selenium status in Turkey. Agricl Sci. 2014;5(2): 87–93. 24. Al-Ahmary KM. Selenium content in selected foods from the Saudi Arabia market and estimation of the daily intake. Arabian J Chem. 2009;2(2):95–9. 25. McNeal JM, Balistrieri LS. Geochemistry and occurrence of selenium: an overview. In: Jacobs LW, editor. Selenium in agriculture and the environment. Madison, Wisconsin: SSSA Special Publication; 1989. 26. Lemire M, Fillion M, Barbosa F Jr, Guimaraes JR, Mergler D. Elevated levels of selenium in the typical diet of Amazonian riverside populations. Sci Total Environ. 2010;408(19):4076–84. 27. Saha U, Fayiga A, Sonon L. Selenium in the soil-plant environment: a review. Int J Appl Agric Sci. 2017;3(1):1–18. 28. Shaheen SM, Frohne T, White JR, DeLaune RD, Rinklebe J. Redox-induced mobilization of copper, selenium, and zinc in deltaic soils originating from Mississippi (U.S.A.) and Nile (Egypt) River Deltas: a better understanding of biogeochemical processes for safe environmental management. J Environ Manage. 2017;186(Pt 2):131–40. 29. Costa-Silva F, Maia M, Matos CC, Calçada E, Barros AIRNA, Nunes FM. Selenium content of Portuguese unifloral honeys. J Food Compos Anal. 2011;24(3):351–5. 30. Sirichakwal PP, Puwastien P, Polngam J, Kongkachuichai R. Selenium content of Thai foods. J Food Compost Anal. 2005;18(1):47–59. 31. Pappa EC, Pappas AC, Surai PF. Selenium content in selected foods from the Greek market and estimation of the daily intake. Sci Total Environ. 2006; 372(1):100–8. 32. Favorito JE. An investigation into selenium geochemistry in phosphate mine soils. [Doctoral Dissertations]. Faculty of the Virginia Polytechnic Institute and State University; 2017. 33. dos Santos M, da Silva Júnior FMR, Muccillo-Baisch AL. Selenium content of Brazilian foods: a review of the literature values. J Food Compost Anal. 2017; 58:10–5. 34. Seixas TG, Moreira I, Malm O, Kehrig HA. Mercury and selenium in a top- predator fish, Trichiurus lepturus (Linnaeus, 1758), from the tropical Brazilian Coast, Rio de Janeiro. Bull Environ Contam Toxicol. 2012;89(2):434–8. 35. Johnston JN, Savage GP. Mercury consumption and toxicity with reference to fish and fish meal. Nutr Abstr Rev. 1991;61:73–116. 36. Yaroshenko FA, Dvorsaka YE, Surai P, Sparks NH. Selenium-enriched eggs as a source of selenium for human consumption. Food Sci Policy. 2003;1:13–23. 37. Gao Y, Walder K, Sunderland T, Kantham L, Feng HC, Quick M, et al. Elevation in Tanis expression alters glucose metabolism and insulin sensitivity in H4IIE cells. Diabetes. 2003;52(4):929–34. 38. European Food Safety Authority (EFSA) Panel on Additives Products or Substances used in Animal Feed. Safety and efficacy of selenium compounds (E8) as feed additives for all animal species: sodium selenite, based on a dossier submitted by Todini and Co SpA. EFSA Journal. 2016; 14(3):4442. 39. Yu D, Liang D, Lei L, Zhang R, Sun X, Lin Z. Selenium geochemical distribution in the environment and predicted human daily dietary intake in northeastern Qinghai. China. Environ Sci Pollut Res Int. 2015;22(15):11224–35. 40. Fairweather-Tait SJ, Bao Y, Broadley MR, Collings R, Ford D, Hesketh JE, et al. Selenium in human health and disease. Antioxid Redox Signal. 2011;14(7): 1337–83.

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