Zn In Food Research Articles

Assessment of public health risk associated with consumption of dominant edible animal species of the Lagos Lagoon, Nigeria

Heavy metals bio-accumulated in edible aquatic animal species pre-dispose final consumers to adverse health effects of these toxins. Edible animal species were collected from the Lagos lagoon, Nigeria where elevated concentrations of heavy metals have been documented over the years. The concentrations of heavy metals in the animal species were determined and the potential health risk to three age groups of the population, associated with consumption of these species was assessed by calculating Daily Intake of Metals (DIM) and Health Risk Index (HRI). The levels of heavy metals recorded in the tissues of the animal species were below Food and Agricultural Organization (FAO) recommended limits in food, except for Zn (47.60 ppm) in Tympanotonus fuscatus . FAO recommended limits for Zn in food is 30.00 ppm. The DIM and HRI for all heavy metals analyzed were < 1 (unity) in the three animal species and for all age groups indicating that utilization of the species as a protein source does not currently pose serious health risk to consumers. The relative safety associated with utilization of edible animal species from the Lagos lagoon as a protein source reported in this study can only be maintained if heavy metal concentrations in the lagoon are kept within acceptable limits by setting effective effluent limitation standards and enforcing the set standards. Keywords: Bio concentration, Heavy Metals, Pollution, Risk indices, Public Health

Nutrients Removed from the Soil Decide the Nutritional Security of a Nation:The Case of Iron and Zinc in India

National iron (Fe) and zinc (Zn) balance were computed using theoretical mean daily per capita dietary Fe and Zn requirement and composition of Fe and Zn in foods in agriculture, horticulture, animal husbandry and fisheries sectors. The analyses imply a satisfactory situation that the intake of Fe and Zn through food sources by the Indian population is adequate. Despite sufficient availability of Fe and Zn through food, there is widespread Zn and Fe deficiency in our population. Ours is a vegetarian-dominant society. The phytate content of our foods is relatively high as the phytate content of vegetarian diets is high. This may be the main cause of the low absorption of Zn and Fe from the foods we eat. A sector-wise contribution indicated a major share of the agriculture sector, followed by the animal husbandry sector. Surprisingly, horticulture sector contributed a small portion (9.1% Zn and 12.9% Fe). The fisheries sector contributed the least. Given the multiple sources of uncertainty in following this method, caution must be exercised in interpreting the estimated figures for prevalence. Since our food sources are supplying enough Fe and Zn, our research efforts should therefore be diverted towards bioavailability rather than bio-fortification.

Comparison of chemical modifiers for direct determination of Cd, Cu and Zn in food stuffs by solid-sampling-ETAAS

In this work, the capability of different chemical modifiers (Pd, Pd/Mg(NO3)2, Pd/NH4NO3, NH4H2PO4, NH4H2PO4/Mg(NO3)2) to eliminate the matrix effects in the direct determination of Cd, Cu and Zn in food-stuffs by solid sampling-electrothermal atomic absorption spectrometry was compared. The alternative analytical lines were used for determination of Cu (327.4nm) and Zn (307.6nm) in order to allow the introduction of reasonably high sample mass into the furnace. Mixed modifiers containing palladium were useful to eliminate the matrix effect in Cd determination. For Cu and Zn determination the application of Pd shows satisfactory analytical performance. In the determinations of Cd and Zn the phosphate containing modifiers shows elimination of matrix effects only when applying them to a partially pyrolysed sample (at 400°C). The achievable limits of detection for Cd, Cu and Zn in solid samples were 0.279ngg−1; 0.020μgg−1 and 2.04μgg−1, respectively.

Survey and risk assessment of trace elements in foods from Taiwan containing red mould rice (Monascus) by ICP-MS

The concentrations of seven trace elements (As, Cd, Cr, Pb, Se, Cu and Zn) in 93 red mould rice (Monascus) food samples in Taipei, Taiwan, were determined by inductively coupled plasma-mass spectrometry (ICP-MS) after wet digestion. The results, calculated in mg kg−1 (wet weight) for each sample, revealed the general scenario of food safety in Taiwan: As (0.005–12.04), Cd (<0.0005–2.22), Cr (0.014–6.95), Cu (0.012–8.70), Pb (0.001–0.64), Se (<0.001–1.29) and Zn (0.020–67.02). Three food samples were identified with As concentrations higher than regulatory limits: a dietary supplement sample and a seaweed sample with As concentrations that exceeded the limit of Taiwan's health food standard of 2 mg kg−1, and a canned eel sample with an As concentration that exceeded the limit of Canada's fish standard of 3.5 mg kg−1. This study suggests that the estimated intakes of these seven trace elements from the consumption of foods containing Monascus pose little risk, as the trace element contents in the majority of samples were lower than the permissible/tolerable intakes per week according to the guidelines recommended by the Food and Agricultural Organization/World Health Organization (FAO/WHO). Moreover, their concentrations in foods containing Monascus differ widely for different food varieties, suggesting that external contaminants and raw materials are the main sources of trace elements. This study shows that ICP-MS is a simple method proposed for the determination of As, Cd, Cr, Pb, Se, Cu, and Zn in foods containing Monascus.

Fast Determination of Cd, Fe, Pb, and Zn in Food using AAS

Analytical chemistry plays a fundamental role in proposing fast and reliable procedures to analyze food samples. Proper selection and introduction of complementary foods during the breastfeeding period and childhood reduce the vulnerability to micronutrient deficiencies. This study aimed to propose a sensitive approach for the promotion of adequate food supplements regarding Cd, Fe, Pb, and Zn content. These metals were determined using flame atomic absorption spectrometry (Fe and Zn) and thermospray flame furnace atomic absorption spectrometry (Cd and Pb). A simple procedure mixing the sample (100 mg) with 0.1 mol/L HCl was proposed. Cadmium and Zn showed suitable results when a bovine liver certified sample (SRM 1577b) was studied, and the Fe content was strongly correlated to the size of the particle. Cadmium and Pb were not found in the food samples studied.

Metrology in physics, chemistry, and biology

The association of physics and chemistry with metrology (the science of measurements) is well documented. For practical purposes, basic metrological measurements in physics are governed by two components, namely, the measure (i.e., the unit of measurement) and the measurand (i.e., the entity measured), which fully account for the integrity of a measurement process. In simple words, in the case of measuring the length of a room (the measurand), the SI unit meter (the measure) provides a direct answer sustained by metrological concepts. Metrology in chemistry, as observed through physical chemistry (measures used to express molar relationships, volume, pressure, temperature, surface tension, among others) follows the same principles of metrology as in physics. The same basis percolates to classical analytical chemistry (gravimetry for preparing high-purity standards, related definitive analytical techniques, among others). However, certain transition takes place in extending the metrological principles to chemical measurements in complex chemical matrices (e.g., food samples), as it adds a third component, namely, indirect measurements (e.g., AAS determination of Zn in foods). This is a practice frequently used in field assays, and calls for additional steps to account for traceability of such chemical measurements for safeguarding reliability concerns. Hence, the assessment that chemical metrology is still evolving.

In Vitro Availability of Calcium, Iron, and Zinc from First‐Age Infant Formulae and Human Milk

ABSTRACTBackgroundVariation in the bioavailability of calcium (Ca), iron (Fe), and zinc (Zn) occurs because of interactions of food components in the gastrointestinal microenvironment. Bioavailability is preferably determined by in vivo tests, but these are expensive, labor‐intensive, time consuming, and often unethical. As an alternative, in vitro methods can be used to predict bioavailability of nutrients from foodstuffs.MethodsA continuous‐flow dialysis model with preliminary intraluminal digestive phase, adapted to the gastrointestinal conditions of infants younger than 6 months, was used. Human milk was the reference standard. Ca, Fe, and Zn content of samples and dialysates after digestion were analyzed by atomic absorption spectrometry.ResultsCa availability is similar in human milk (13.1% ± 0.8%), whey (13.3% ± 1.2%), and soy‐based formulae (13.0% ± 1.2%;P &gt; 0.05), and higher in casein‐predominant formula (21.2% ± 0.6%;P &lt; 0.05). Availability of Fe is highest in human milk (8.12% ± 0.27%;P &lt; 0.05). Fe availability in whey (1.28% ± 0.28%) and soy formulae (1.48% ± 0.28%) is similar (P &gt; 0.05), but availability is lower in casein‐predominant formula (0.48% ± 0.22%;P &lt; 0.05). Zn availability is also highest in human milk (13.1% ± 0.7%;P &lt; 0.05). However, Zn availability is similar in whey (6.7% ± 0.6%) and casein formulae (8.5% ± 1.6%;P &gt; 0.05), but lower in soy formula (2.3% ± 0.4%;P &lt; 0.05).ConclusionsOur observations are in agreement with previous data from in vivo studies in term infants. This in vitro procedure is an inexpensive, simple, rapid, and reliable method that predicts the bioavailability of Ca, Fe, and Zn in foods.

The Adequacy of Micronutrients in Complementary Foods

The nutritional adequacy of micronutrients depends on their amount and bioavailability in the complementary foods. In many developing countries, cereals or starchy roots and tubers are used as a basis for complementary foods. They are usually prepared as thin gruels, and as a result, their energy and micronutrient content and density are likely to be low, but their content of phytic acid, polyphenols, and/or dietary fiber can be relatively high, all components that can inhibit absorption of certain micronutrients. Nevertheless, there have been very few in vivo isotope studies that have measured the bioavailability of micronutrients directly in complementary foods used in developing countries; some exist for Fe and Zn in complementary foods used in developed countries. Dietary components affecting the bioavailability of Fe and Zn in foods are well-documented.1 Hence, complementary foods can be classified as having high, moderate, or low bioavailability for iron (Fe) and zinc (Zn) based on certain criteria set by the Food and Agricultural Organization and/or the World Health Organization.2,3 Estimates for both Fe and Zn bioavailability depend first on the content in a meal of animal and fish protein relative to plant-based foods. Secondly bioavailability of iron also depends on the content of ascorbic acid, and, for some models, on the consumption of tea or coffee at the same time. For Zn, the calcium (Ca) content ( 1 g Ca/d), and the daily molar ratios of phytate to Zn ( 15) are also important; molar ratios above 15 compromise Zn status. Molar ratios for most complementary foods based on unrefined cereals and legumes probably range from 15 to 36; those based on rice tend to be lower (approximately 15).4 By contrast data on dietary components influencing the bioavailability of copper (Cu), manganese (Mn), selenium (Se), and iodine (I) …

Dynamics of accumulation and decontamination of cadmium and zinc in carnivorous invertebrates. 2. The centipede Lithobius mutabilis Koch.

Metals, being non-degradable, tend to accumulate in animals and hence long-term exposure even to low concentrations of metals may lead to harmful effects. From the physiological point of view, invertebrates may avoid metal poisoning either by retaining metals in inactivate forms, intracellular compartmentalisation or by discharging assimilated metals (Hopkin, 1989). Animals which represent the first strategy are able to concentrate elevated amounts of metals and are regarded as "macroconcentrators" (Dallinger, 1993). The second strategy is exhibited by animals possessing low concentrations of heavy metals, and these are termed “deconcentrators”. Consequently, numerous authors have reported that soil invertebrates belonging to the same trophic level exposed to the same environmental concentrations of metals often display different internal concentrations of metals and strategies for decontamination (e.g., Van Straalen and Van Wensem, 1986; Grodziska et al., 1987; Laskowski and Maryanski, 1993). In the trophic level containing predators, “macroconcentrators” are represented by spiders, “deconcentrators” by carabid beetles, whilst centipedes are regarded as being intermediate between these two extremes. Thus, an investigation comparing these three taxonomic groups in terms of kinetics of metals would be especially interesting. In the previous paper I have investigated the accumulation and decontamination dynamics of Zn and Cd in a carabid beetle Poecilus cupreus L. and showed that carabids exposed to elevated concentrations of Zn in food were able to maintain internal Zn concentrations at a constant level (Kramarz 1999). Although Cd concentrations increased in beetles fed Cd-contaminated food, its excess was quickly and efficiently excreted when switched to uncontaminated food. Additionally, zinc and cadmium did not affect each others uptake by P. cupreus (Kramarz, 1999). In this paper I report the results of the experiment on kinetics of the same metals, Zn and Cd in a centipede Lithobius mutabilis Koch.

Accumulation of Zn, Cu, Pb and Cd in the garden snail ( Helix aspersa): Implications for predators

Accumulation of Zn, Cu, Pb and Cd was studied in snails fed for 120 days on diets contaminated with each metal separately and with all metals mixed together. The concentrations of Zn in food were in the range 39 to 12 200 mg kg −1, Cu 9–1640 mg kg −1, Pb 0.4–12 700 mg kg −1, and Cd 0.16–146 mg kg −1 on a dry weight basis. At the highest concentrations of all metals the consumption rates decreased significantly. For the remaining concentrations, Zn and Cu were accumulated in soft tissue in proportion to their concentrations in food. The lowest treatments of Pb and Cd did not cause any increase in soft tissue concentrations of these metals but at average treatments, a clear increase was observed. Copper was accumulated especially efficiently, exceeding concentrations in food throughout the whole range of treatments. Except for the lower end of experimental treatments, Zn was accumulated approximately in direct proportion to its concentration in the diet. Lead was the most efficiently regulated metal, with soft tissue concentrations always substantially lower than in food. Approximately 60% of Zn, 90% of Cu, 43% of Pb and 68% of Cd on average was assimilated from food. The assimilation efficiency of food alone was ca 74%. The concentrations of metals in shells increased significantly with exposure, but (with one exception) the concentrations in shells did not exceed 5% of those found in soft tissue. We argue that snails are more important as agents of food-chain transport of Cu and Cd, than of Zn or Pb. Our results indicate also that snails are not able to deposit significant quantities of metals in their shells, at least during the time scale of our laboratory experiment.

Selective spectrofluorimetric determination of Zn with 5,7-dibromo 8-quinolinol and its application to food and biological samples analysis.

5,7 dibromo-8-quinolinol (L) with Zn(II) (M) forms a ML 2 fluorescent complex extractable into ether (λ exc=410 nm,λ em= 550nm). This complex is used to provide a sensitive method for determination of Zn. The optimum pH is within 5.5 –7.5 and calibration graph is linear up to 1.0 ppm of Zn. The limit of detection is 6 ng ml −1. The method has been employed to determine Zn in food and biological samples.

Zinc nutriture in the elderly in relation to taste acuity, immune response, and wound healing

A comprehensive review is presented concerning the role of zinc (Zn) nutrition in taste acuity, immunity and wound recovery in the elderly. Specific attention is given to Zn in foods, Zn bioavailability, evidence of Zn deficiency, and the need for Zn in immune function. It was concluded that the mean daily Zn intake in groups of US elderly ranges from 7-13 mg. Dietary Zn intake appears to be related to energy intake. An apparently adequate Zn intake can be achieved for $1.50-2.00/day with careful food selection; hence, people spending below $1.50/day for food have limited ability to satisfy dietary Zn requirements. Further Zn bioavailability should be considered in the food selection process. Evidence suggests that some elderly individuals have a deficient Zn nutriture, but available data are insufficient to ascertain the frequency of this deficiency. Most instances of hypogensia in the elderly, however, are unrelated to Zn nutriture. Deficient Zn nutriture seems to contribute to poor healing in the elderly, but, again, the data are too few to ascertain frequency. Self-treatment with Zn greater than the RDA may be unwise. (wz)

Cadmium and zinc accumulation and elimination by freshwater crayfish.

A theoretical compartment model for the uptake of Cd and Zn by the freshwater crayfish, Procambarus acutus acutus (Girard), was constructed, and included a factorially designed experiment to study the relative importance of food and water as uptake vectors for 109Cd and 65 Zn. Food and water were important pathways for Cd accumulation and the two uptake vectors were first order, independent, and additive. The rate of Cd elimination was not significantly different from zero during either the uptake or depuration phases. Rate constants for uptake from 5 and 10 micrograms Cd . L-1, calculated on a concentration basis, were 0.84 +/- 0.031 and 0.83 +/- 0.029 day-1, respectively. Although there was not measurable Cd elimination, crayfish reached a steady state concentration of about 12.5 micrograms Cd . g-1, dry weight. A small amount of Zn was accumulated via food, relative to that accumulated from water; the former had a much longer retention time than the latter, which was lost rapidly. When Zn in food was the only source, steady state was reached rapidly; Zn accumulation from food and water was not additive. Zn accumulated from water, reached no steady state. Zn uptake was proportional to water concentrations within the fed treatment groups and those not fed Zn-contaminated food. Zn elimination was first order to Zn concentration in the crayfish. Rate constants for Zn accumulation from 50 and 100 micrograms Zn . L-1 when fed Zn-contaminated food were 1.34 +/- 0.064 and 1.46 +/- 0.073 day-1 (estimate +/- 95% CI based on concentration), respectively, while rate constants for Zn elimination were 0.034 +/- 0.0021 and 0.05 +/- 0.0032, respectively.

Cadmium, lead, copper and zinc in food, feces and organs of humans. Interrelationships in food and feces and interactions in the liver and the renal cortex.

The concentrations of Cd, Pb, Cu and Zn in food, feces and organs were analyzed in order to study the interrelationships among these metals in humans. Correlation coefficients and the ratio of all 4 metals in these media were calculated, and the following results were obtained: the ratios of Cd to Cu and Cd to Zn in the renal cortex showed 100 times higher and those ratios in the liver showed 10 times higher than those in food and feces. How-ever, Pb/Cu and Pb/Zn ratios did not vary in these media. Intimate correlations between Cd and Zn were found in the organs in spite of the fact that they showed no correlation in food and feces. Cu and Zn indicated high correlations in food, feces and renal cortex, but not in the liver. Thus this study indicates that the proportions of the metals ingested via food and excreted in feces are almost the same, i.e., the absorption rates are not greatly different. However, once absorbed, the relationships among the metals are markedly altered, suggesting different metabolism by individual metal and/ or possibly metal-metal interactions in the human organs, particularly in the renal cortex and the liver.