Nutrition essential elements

J.L. Johnson, Handbook of Nutritionally Essential Elements, Marcel Dekker, New York (1997). 

The assessment of plant-available soil contents can frequently be achieved and validated by field experiments for nutritionally essential elements, and, for a few potentially toxic elements such as chromium, nickel and molybdenum, at the moderately elevated concentrations that can occur in agricultural situations. The validation of extraction methods, devised for agricultural and nutritional purposes, is much less easy to achieve when they are applied to heavy metals and other potentially toxic elements, especially at the higher concentrations obtained in industrially contaminated land. This is not surprising in view of the fact that for some heavy metals, for example lead, there is an effective root barrier, in many food crop plants, to their uptake and much of the metal enters plants not from the root but by deposition from the atmosphere on to leaves. In these circumstances little direct correlation would be expected between soil extractable contents and plant contents. For heavy metals and other potentially toxic elements, therefore, extraction methods are mainly of value for the assessment of the mobile and potentially mobile species rather than plant-available species. This assessment of mobile species contents may well, however, indicate the risk of plant availability in changing environmental conditions or changes in land use. 

Another application of slowly soluble phosphate glasses is in animal nutrition. Essential elements are incorporated in the glass (Table 12.26) which can then be swallowed in the form of a pill by ruminant animals. The glass pill remains lodged in the rumen for several months, from where it slowly releases the desired nutrient elements [16,17] (Section 12.3). Slowly soluble phosphate glasses containing pharmaceuticals may in the future be implanted in animals, or even humans, on a routine basis. Further developments in this area are awaited with interest (Section 12.13). 

Center for Disease Control and Prevention (CDC), U. S. Department of Health and Human Services. Physical Activity and Good Nutrition Essential Elements for Good Health, At-a-Glance 2000. Atlanta CDC, 2000... 

Minerals. Nuts are considered to be a good source of minerals essential for nutrition, supplying elements of copper, manganese, iron, and sulfur (see Mineral nutrients). The values for the mineral constituents of many nuts shown in Table 2 are averages of available analytical data. Values for the mineral content of the peanut kernel (28) and ash constituents in the macadamia kernel (29) and cashew (26) have also been reported. Chufa nuts have a high sihcon content. 

Chlorine. Nearly all chlorine compounds are readily soluble in water. As a result, the major reservoir for this element in Figure 1 is the ocean (5). Chloride, as noted earHer, is naturally present at low levels in rain and snow, especially over and near the oceans. Widespread increases in chloride concentration in mnoff in much of the United States can be attributed to the extensive use of sodium chloride and calcium chloride for deicing of streets and highways. Ref. 19 points out the importance of the increased use of deicing salt as a cause of increased chloride concentrations in streams of the northeastern United States and the role of this factor in the chloride trends in Lake Ontario. Increases in chloride concentration also can occur as a result of disposal of sewage, oil field brines, and various kinds of industrial waste. Thus, chloride concentration trends also can be considered as an index of the alternation of streamwater chemistry by human development in the industrialized sections of the world. Although chlorine is an essential element for animal nutrition, it is of less importance for other life forms. 

The toxicokinetic and toxicological behavior of lead can be affected by interactions with essential elements and nutrients (for a review see Mushak and Crocetti 1996). In humans, the interactive behavior of lead and various nutritional factors is particularly significant for children, since this age group is not only sensitive to the effects of lead, but also experiences the greatest changes in relative nutrient status. Nutritional deficiencies are especially pronounced in children of lower socioeconomic status however, children of all socioeconomic strata can be affected. 

Animal studies indicate that nutritional deficiencies in a number of essential elements (e.g., calcium, iron, zinc, copper, phosphorus) may impact the toxicokinetic and toxicological behavior of lead (ATSDR 1993 Chaney et al. 1989). In infants and children, lead retention has been shown to be inversely correlated with calcium intake (Johnson and Tenuta 1979 Sorrell et al. 1977 Ziegler et al. 1978). Zinc has been shown to have a protective effect against lead toxicity in a number of animal species (Goyer 1986 Haeger-Aronsen et al. 1976 Brewer et al. 1985 Cerklewski and Forbes 1976). 

In the control area, Lombador, the phosphorus, an essential element in plants nutrition, presents, in the relationsoil-plant, a different behavior from the other areas. This can be related to the substratum rock in the Lombador area which is composed of metassediments (turbidites) and are not included in Volcano Sedimentary Complex as the other areas where mining works have occurred. 

System 242. human nutrition, foodstuffs (XIV) balanced essential trace element daily intake for humans (XVI) human health (XVIII). Research should be carried out on the endemic diseases induced by deficient or excessive content in the biogeochemical food webs of different essential elements, like N, Cu, Se, I, F, Mo, Sr, Zn, etc. 

M. O. Schultze stated that cobalt is an essential element for the nutrition of sheep and cattle. Although it is not essential for the growth of the herbage plants, they nevertheless take it up from the soil and make it available for animal nutrition (106) To prevent anemia, even when the diet contains adequate amounts of iron, a small amount of cobalt (not more than four micrograms per day per kilogram of body weight of sheep) is required (124). It is an important constituent of vitamin B 2. 

L.-J. Proust detected manganese in the ash of the pine, the fig tree, the calendula, and other plants (144). In 1849 Prince Salm-Horstmar found it in the ash of the oat plant (45). According to A. T. Shohl, plants store manganese in their leaves and seeds, and use it as an essential element in their nutrition (146). 

Size exclusion chromatography coupled to an ICP-QMS with an octopole collision cell was employed for the multi-elemental speciation of essential elements (P, S, Cr, Mn, Fe, Co, Cu, Zn, Br, Se and I) and Al as a toxic element in premature human milk.28 Comparison of speciation results demonstrates that premature human mothers milk differs significantly from formula milks in terms of the element binding pattern to the biomolecules. It was found that premature human milk is very rich in high molecular weight species associated with metals. The authors concluded that more attention must be paid to the chemical form in which essential elements are added to the formulas, particularly those used for the nutrition of premature babies.28... 

What is the likelihood that other elements will be found essential Consider a human red blood cell, an object of volume 80 pm3 and containing about 3 x 108 protein molecules (mostly hemoglobin). About 7 x 105 atoms of the "trace metal" copper and 105 atoms of the nutritionally essential tin are present in a single red cell. Also present are 2 x 104 atoms of silver, a toxic metal. Its concentration, over 10 7 M, is sufficient that it could have an essential catalytic function. However, we know of none and it may simply have gotten into our bodies from handling money, jewelry, and other... 

Nickel as an essential element in ruminant nutrition has not been proved conclusive as of tile early 1980s. However, with nonruminants, some evidence indicates that certain species fed low-nickel diets have a greater infant mortality rate and a general degradation of the reproductive process (Nielsen, 1975 A nice et al., 1973). 

Compared to a number of other metals, vanadium appears to be relatively innocuous when ingested in low concentrations by animals however, it is by no means certain that this will be true for chronic exposure, as toxic effects have been reported [80], The nutrition community treats vanadium as a member of the ultra trace metals, which have a nutritional requirement of less than 1 mg/kg diet and are present in tissues in the range of micrograms per kg [81]. Although evidence suggests that vanadium is beneficial to human health, its mechanism of action remains obscure. No specific dietary recommendations have been made, in part, because there is controversy surrounding whether or not vanadium is an essential element. 

Sodium is an essential element and additions of sodium chloride to soils can provide increased yields of some plants. There is some degree of overlap in the roles of sodium and potassium in plant nutrition. Both Na and Rb are beneficial in K-deficiency. 

Zinc is easily taken up by plants from the soil where it accumulates in the shoots. It is an essential element for plant nutrition (Marschner, 1986) and is important in both carbohydrate metabolism and protein synthesis. 

Element uptake from soil and transfer into the edible parts of plants have been addressed in several other studies. Soil-to-plant transfer factors in fruit and vegetables grown in various agricultural conditions have been determined for, for example, Pt [100], T1 [101], and various other metal contaminants [102], In a study on stable isotopes of fission product elements (Ce, Cs, Sr), an in vitro enzy-molysis method has been applied to investigate the solubilization of the analytes from fodder in a simulated ruminant digestion [103], The effect of inhibitors of fission product solubility was also considered and essential elements were determined simultaneously to evaluate potential nutrition problems for the animals from the use of such inhibitors. Selective leaching of individual classes of metal complexes with different ligands and sequential enzymolysis have been recently applied to estimate the potential bioavailability to humans of Cd and Pb in cocoa powder and related products [104]. 

Inductively Coupled Plasma Atomic Emission Spectrometry ICP-AES is a technique half-way between FAAS and ET-AAS in terms of detection power. Among all ICP-AES features its robustness against matrix effects and its ability to carry out multielemental analysis predominate as the most advantageous [76-80], Multielemental analysis has also been successfully used to establish reference values [6, 76, 81-84] for many major and trace essential elements in different matrices of biological and nutritional interest, particularly in milk samples [81-83], Reference values for minor and trace element in human milk are collected in Table 13.8. 

From a nutritional viewpoint, it is necessary to stress the current importance of carrying out the multielemental analysis of milk samples (either human, cow s, or formula milk) in order to establish the reference values of essential elements and quantify the levels of potentially toxic elements. This fact is more relevant to formula milk production for premature babies as some essential elements are not stored by the fetus during its development in the uterus. Attention has been already paid to the qualitative and quantitative composition (analysis) of proteins, lipids, carbohydrates, and, of course, essential elements. However, in the case of human nutrition, knowledge on the particular species (compounds) in which a given element is present (chemical speciation) is now urgently needed, because the absorption and bioavailability of the essential element will strongly depend on that particular chemical form. Thus, although only the total element daily requirements have been considered here, it is important to stress that more attention must be paid to the chemical form in which essential and potentially toxic elements are present in milk. Such aspects are dealt with in detail in Chapter 13 by B. Michalke et al. 

Human milk (or the substitute food, formula milk) is the only source of essential trace elements for newborns. To ensure the optimum development of the baby, mother s milk contains essential elements at the adequate levels. However, today it is well known that bioavailability, biological activity, nutritional value, as well as toxicity and metabolism of trace metals and metalloids strongly depend of their... 

Growth is rapid and many systems develop their adult cell number and composition throughout the first year of life. Optimal nutrition is thus most critical in this early period. Milk - the only source of food for the offspring of all mammals in the early months of life - cannot meet the demands of optimal growth later on in the first year of life. This is especially so with the essential elements such as iron and manganese whose low content in milk (18-23) does not meet the needs of a fast growing organism (24-27). 

Numerous trace elements are known to be nutritionally essential in man In order to assess the essentiality, dietary availability, and metabolic fate of these, means of labeling for subsequent identification are needed In animal studies, radioisotopes are often used for this purpose, but their use in human studies is generally contraindicated due to the radiation hazards An alternate method is to use stable isotopes of the elements, which overcomes this limitation A method will be described for conveniently measuring the stable isotopes of selenium, permitting their use as metabolic tags in tracer studies Using one stable isotope as the tracer and another as internal standard, one can quantitatively identify in a sample the tracer, natural (unenriched) selenium present with it, and total selenium Some of the kinds of information obtainable from metabolic tracer studies will be discussed ... 

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