Prebiotics and the Bioavailability of Minerals and Trace Elements

Abstract

Promising evidence exists for a stimulatory influence of prebiotic carbohydrates (non‐digestible oligosaccharides (NDO) and lactulose) on the bioavailability of minerals and trace elements, although most information is available from rat experiments. Because the number of human studies is limited, additional research is needed, especially studies that focus on the long‐term effects of prebiotics on bone metabolism. The hypothesized mechanisms suggest that prebiotics that result in a strong pH reduction, a pronounced osmotic effect, a stimulation of the exchange of protons, an increased level of butyrate and calbindin, and an enlarged surface area in the colon may be promising candidates for increasing the absorption of minerals and trace elements. Because the place of colonic fermentation seems to be of influence in these mechanisms, the use of mixtures of different types of prebiotics is of special interest. Probiotics are involved in most prebiotic‐related mechanisms, possibly mediated in part by the production of polyamines. Therefore, the combined use of pre‐ and probiotics may yield promising results. More detailed information on the present state‐of‐the‐art concerning the effects of prebiotics on the bioavailability of minerals and trace elements in different life stages, discussed by study design and its underlying mechanisms, can be found in this review.     

Use of stable isotopes to assess the bioavailability of trace elements: a review

The bioavailability (utilization) of trace elements is very variable, depending on the characteristics of the element itself, composition of the diet, gastrointestinal conditions and other physiological factors. To derive dietary recommendations and make use of emerging information on diet-gene interactions relating to nutritional requirements for trace elements, methods for assessing bioavailability are required. The trace elements of particular interest include iron, zinc, selenium and copper because of problems of deficiency, purported links with chronic diseases, and the growing market in fortified foods and supplements. The absorption and subsequent metabolism of trace elements can be monitored using stable isotope tracers, but there are difficulties associated with this approach. Although radioisotopes offer many advantages over stable isotopes, their use is restricted due to safety and ethical issues. The difficulties and limitations of methodologies associated with labelling of trace elements in foods with stable isotopes, design of human studies to generate results that predict bioavailability, and detection and quantification of stable isotopes in biological samples are discussed.     

Intestinal bioavailability of minerals and trace elements from milk and beverages in humans

The intention of this review is to summarize the results of studies measuring the fractional absorption (in %) of minerals and trace elements from milk and beverages in humans. The absorption rates of the minerals calcium and magnesium and the essential trace elements iron, copper, zinc, and manganese are presented and discussed separately. The data given in this review have practical relevance especially in estimating the amount of a nutrient, which is absorbed from a liquid meal. Furthermore this paper also discusses dietary compounds modulating intestinal nutrient bioavailability at the luminal or 8 mucosal level.     

Intake of Pro- and/or Prebiotics as a Promising Approach for Prevention and Treatment of Colorectal Cancer

Colorectal cancer (CRC) is the third most common type of cancer, posing a serious threat to human life. It is widely believed that dietary factors may be crucial modifiers of CRC risk, with pro-and/or prebiotics being especially promising. In this review, a synthesis of CRC prevention and treatment of strategies relying on usage of pro- and/or prebiotics supplements is given, as well as discuss mechanisms underlying the contribution of pro-and/or prebiotics to the suppression of colonic carcinogenesis. Furthermore, a framework for personalizing such supplements according to the composition of an individual's gut microbiome is suggested. Various factors including diversity of one's intestinal microflora, integrity of their intestinal barrier, and the presence of mutagenic/carcinogenic/genotoxic and beneficial compounds are known to have a prominent influence on the development of CRC; thus, clarifying the role of pro- and/or prebiotics will yield valuable insight toward optimizing interventions for enhanced patient outcomes in the future.     

Combating Mineral Malnutrition through Iron and Zinc Biofortification of Cereals

Iron and zinc are 2 important nutrients in the human diet. Their deficiencies in humans lead to a variety of health‐related problems. Iron and zinc biofortification of cereals is considered a cost‐effective solution to overcome the malnutrition of these minerals. Biofortification aims at either increasing accumulation of these minerals in edible parts, endosperm, or to increase their bioavailability. Iron and zinc fertilization management positively influence their accumulation in cereal grains. Regarding genetic strategies, quantitative genetic studies show the existence of ample variation for iron and zinc accumulation as well as inhibitors or promoters of their bioavailability in cereal grains. However, the genes underlying this variation have rarely been identified and never used in breeding programs. Genetically modified cereals developed by modulation of genes involved in iron and zinc homeostasis, or genes influencing bioavailability, have shown promising results. However, iron and zinc concentration were quantified in the whole grains during most of the studies, whereas a significant proportion of them is lost during milling. This makes it difficult to realistically assess the effectiveness of the different strategies. Moreover, modifications in the accumulation of toxic elements, like cadmium and arsenic, that are of concern for food safety are rarely determined. Trials in living organisms with iron‐ and zinc‐biofortified cereals also remain to be undertaken. This review focuses on the common challenges and their possible solutions related to agronomic as well as genetic iron and zinc biofortification of cereals.     

Prebiotics and Iron Bioavailability—Is There a Connection?

ABSTRACT: Poor bioavailability of dietary iron, especially from diets rich in cereals and legumes, is a major factor contributing to the high prevalence of nutritional iron deficiency in developing countries. Dietary modification to increase intake of components that promote iron absorption from low-bioavailability meals is an effective strategy for combating nutritional iron deficiency. Prebiotics are nondigestible oligosaccharides that selectively stimulate the growth and activity of specific species of bacteria in the colon with benefits to human health. Common prebiotics such as inulin and fructooligosaccharides occur naturally in a wide variety of plant-based foods and have recently been suggested to have an enhancing effect on iron absorption. The hypothesis that prebiotics enhance iron absorption is biologically plausible because fermentation of prebiotics by natural microflora present in the colon may decrease the pH of the luminal content, promote reduction of Fe(III) to Fe(II), stimulate proliferation of epithelial cells to expand the absorptive surface area, and potentially stimulate expression of mineral-transport proteins in epithelial cells. However, data available in the literature characterizing the enhancing properties of prebiotics on iron absorption are inconsistent, and mechanisms of actions involved are poorly understood. The notion that the colon can function as a significant site of iron absorption in response to stimulation by prebiotics, and the effect of long-term exposure to prebiotics on the iron status of iron-deficient subjects remain to be clarified. This review discusses the functional properties of prebiotics as a promising dietary factor that enhances iron absorption. Keywords: prebiotics, iron, colon, oligosaccharides, inulin     

果酸钙和其它钙源对预防骨质疏松症的比较研究

在10000年前的农业时代初期，人类学就认为人类一直是钙的高吸收者。如果现代人类与旧石器时代人类的基因完全相同，则现代人类饮食中的钙只能被吸收三分之一，钙撮入量明显不足，满足不了人体的生理需求。对钙和骨质的分析研究表明：青少年、成年人、老人以及绝经后的女性每日撮入500-1500mg钙有利于骨质生长。由于果酸钙具有较高的生物吸收利用性，已成为当前钙研究的主题。果酸钙对青春期女孩、青年和绝经后妇女都起了积极的作用，而且微量元素和Vo的存在更有利于人体增强骨密度，降低骨折发生率。     

Trace element food toxicology: An old and ever‐growing discipline

Food toxicology (FT) is an old science whose origins may go back to primitive humans. However, due to major environmental damage, daily market launches of new food products, and the analytical ability to detect ever smaller quantities of toxicants in foods, FT is also an ever‐growing science with an enormous task ahead. With respect to trace elements, current research trends can be encompassed under the headings of detection, control, and toxicological evaluation. Under the heading detection, quality, sensitivity, speed, automation, and specificity for each food type are the characteristics currently sought when developing new methodologies. Under control, there is a great need for constant monitoring, on an international level, of the levels of trace elements present in foods; and for development and application of new methodologies to guarantee product and process safety. Under toxicological evaluation, information about the bioavailability of trace elements and consequently studies of the chemical species present in foods have top priority. The work still outstanding in the study of trace element FT is immense, because it is necessary to achieve a profound understanding of the toxicological characteristics of food products in relation to trace elements; to give information to food manufacturers that they can use to adapt their production so that it meets the requirements of international legislation and demands for quality and innocuousness on the part of the market and consumers; and to develop standards regulating the maximum content of trace elements, according to the content of the various species.     

Nutrition, immune response, and outcome

The immune system plays a key role in the body's ability to fight infection and reduce the risk of developing tumors, autoimmune and degenerative disease. Nutritional deficiencies and excesses influence various components of the immune system. Early studies investigating the association between nutrition and immunity focused on generalized protein-energy malnutrition, particularly in children in developing countries. The extent of immunological impairment depends not only on the severity of malnutrition but on the presence of infection and on the age of onset of nutritional deprivation, among other factors. In industrialized nations, immune function has been shown to be compromised in many malnourished hospitalized patients, small-for-gestational age infants, and the elderly. Obesity also may adversely influence immune function. Imbalances of single nutrients are relatively uncommon in humans, and investigations of protein and amino acids and specific vitamins, minerals, and trace elements generally are carried out in experimental animals. Deficiencies of protein and some amino acids, as well as vitamins A, E, B6 and folate, are associated with reduced immunocompetence. In contrast, excessive intake of fat, in particular polyunsaturated fatty acids (e.g. linoleic and arachidonic acids), iron, and vitamin E are immunosuppressive. Trace elements modulate immune responses through their critical role in enzyme activity. Both deficiency and excess of trace elements have been recognized. Although dietary requirements of most of these elements are met by a balanced diet, there are certain population groups and specific disease states which are likely to be associated with deficiency of one or more of these essential elements. The role of trace elements in maintenance of immune function and their causal role in secondary immunodeficiency is increasingly being recognized. There is growing research concerning the role of zinc, copper, selenium, and other elements in immunity and the mechanisms that underlie such roles. The problem of interaction of trace elements and immunity is a complex one because of the frequently associated other nutritional deficiencies, the presence of clinical or subclinical infections which in themselves have a significant effect on immunity, and finally the altered metabolism due to the underlying disease. There are many practical applications of our recently acquired knowledge regarding nutritional regulation of immunity.(ABSTRACT TRUNCATED AT 400 WORDS)     

Association between the gut microbiota and mineral metabolism

The aim of this review is to present the most recent scientific evidence of interactions between the intestinal microbiota and minerals, and the effect of this interaction on the health of the host. The Web of Science database from the years 2013–2017 on this topic was reviewed. Numerous in vitro studies have shown that iron significantly affects the intestinal microbiota. However, Bifidobacteriaceae are capable of binding iron in the large intestine, thereby limiting the formation of free radicals synthesized in the presence of iron, and thus reducing the risk of colorectal cancer. Animal studies have revealed that supplementation with probiotics, prebiotics and synbiotics has a significant effect on bone calcium, phosphate and bone metabolism. The dynamic interaction between microbiota and zinc was shown. Human studies have provided evidence of the influence of probiotic bacteria on parathormone, calcium and phosphate levels and thus on bone resorption. Recent studies have produced new information mainly on the impact of the intestinal bacteria on the metabolism of calcium and iron. From a scientific perspective, the most urgent fields that remain to be investigated are the identification of all human gut microbes and new therapies targeting the interaction between intestinal bacteria and minerals. © 2017 Society of Chemical Industry     

Mineral and trace element concentrations in cultivars of tomatoes

The concentrations of minerals (P, Na, K, Ca and Mg) and trace elements (Fe, Cu, Zn and Mn) were determined in 167 tomato samples belonging to five cultivars (Dorothy, Boludo, Dunkan, Dominique and Thomas) produced on the island of Tenerife. The contribution to the intake of minerals and trace elements was in general low, with special emphasis on the contributions of K and Mg. The cultivar, cultivation method, period of sampling and region of production in the island influenced the concentrations of minerals and trace elements of the tomatoes. Trace elements seemed more influenced by the cultivar than the minerals, and the cultivation method affected mineral contents more than trace element contents. The period of sampling had an important influence on the mineral and trace elements. Many correlations were observed between the minerals and trace elements studied. Applying discriminant analysis, the tomato samples tended to be classified according to the cultivation method, period of sampling and region of cultivation.     

Modification of an in-vitro method for estimating the bioavailability of zinc and calcium from foods

A continuous flow in-vitro method for estimating the bioavailability of minerals and trace elements was modified. This modified method includes a simulated gastric digestion with pepsin, gradual pH change during the first 30 min of dialysis in an Amicon stirred cell, and a further 2 h of continuous dialysis accompanied by intestinal digestion with pancreatin-bile extract. The percentage of continuously dialysed minerals or trace elements (dialysability) is used to express the bioavailability. Comparison of different in-vitro methods by using the dialysability of zinc and calcium from milk- and soy-based formula samples revealed that with the modified method the results are closer to the in-vivo situation and could be used as a relative index for predicting the bioavailability of some minerals and trace elements.

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Modifikation einer in-vitro-Methode zur Bestimmung der Bioverfügbarkeit von Zink und Calcium aus Lebensmitteln

Zusammenfassung Eine continuous-flow-Methode zur in-vitro-Bestimmung der Bioverfügbarkeit von Mineralien und Spurenelementen wurde verbessert. Die Proben werden mit Pepsin in einer Dialysezelle verdaut, der pH-Wert dabei graduell verändert und bei der nachfolgenden Verdauung mit Pankreas-Galle-Extrakt die freigesetzten Mineralstoffe kontinuierlich durch Dialyse abgezogen. Der dialysierbare Anteil gilt als Maß für die Bioverfügbarkeit. Ein Vergleich der so erhaltenen Daten für Zink und Calcium aus Milch- und Soja-Formulanahrung zeigt gute Übereinstimmung mit in-vivo-Messungen. Die Methode dürfte sich zur Vorhersage der Bioverfügbarkeit für Mineralstoffe eignen.

     

Modulation of chelating factors,trace minerals and their estimated bioavailability in Italian and African sorghum (Sorghum bicolor (L.) Moench) porridges

Factors able to modulate chelating factors, trace minerals and their bioavailability were investigated in porridges of five sorghum (Sorghum bicolor (L.) Moench) varieties: from Nigeria, Senegal, Burkina Faso and two from Italy. Effects of variety and traditional fermentation and cooking were assessed on iron‐binding phenolic groups, phytates and iron and zinc content and bioavailability. Chelating factors, trace elements as well as the effect of processing (mainly fermentation) were modulated by variety. Fermentation decreased iron‐binding phenolic groups until 49% and phytate content until 72% as well as increased phytase activity 3.4–16.4 fold, leading to enhancement of iron and zinc estimated bioavailability. Cooking alone had almost no effect. The lowest chelating factors content and the highest trace minerals bioavailability were shown by fermented Senegal landrace, whereas the Italian varieties overall showed the worst results. The results indicate that selection of traditional varieties and appropriate processing methods can improve sorghum nutritional value.     

益生素、益生菌与结肠癌

介绍了益生素和益生菌及其作用机理。在动物模型中，有大量的数据证实益生素和益生菌能够预防癌症．而在人体内还没有直接实验证据。它们抑制癌症的确切机理目前尚不清楚，其抑制机理可能是：肠道菌群代谢活动的改变，肠道理化环境的改变，潜在的致癌物质的黏附和降解，肠道菌群的改变、抗癌或抗诱变物质的形成、提高宿主的免疫应答、影响宿主的生理活动以及发酵不能被消化的食物并形成有益代谢产物。     

A review of the effects and mechanisms of polyphenolics in cancer

This paper is a comprehensive review of the effects of bioactive polyphenolic compounds commonly found in many fruits and vegetables on cancer. These include the pheniolic acids, anthocyanins, catechins, stilbenes and several other flavonoids. We have attempted to compile information from most of the major studies in this area into one source. The review encompasses the occurrence and bioavailability of the polyphenolics, the in vitro and in vivo evidence for their effects on cancer, both positive and negative, and the various mechanisms by which the chemicals may exert their effects. Although most of the work done to date indicates a chemopreventative activity of these compounds, there are some studies that show cancer-inducing or no effects. There are several common mechanisms by which these chemicals exert their effects that could be conducive to additive, synergistic, or antagonistic interactions. These include effects on cellular differentiation, proliferation, and apoptosis, effects on proteins and enzymes that are involved in these processes at a molecular level, and other various effects through altered immune function and chemical metabolism.     

Effect of plant cultivation methods on content of major and trace elements in foodstuffs and retention in rats

BACKGROUND: Many consumers perceive organic foods as more nutritious than conventional foods. However, the existing evidence is insufficient to support or refute this belief. The purpose of the present study was to investigate the effect of three different model cultivation systems on selected major and trace element contents of dried foodstuffs (carrots, kale, peas, potatoes and apples) grown in two consecutive years, as well as mineral retention determined in 36 rats (second generation in a multi‐generation study) fed diets based on these foodstuffs from one year. RESULTS: Overall, there was no evident trend towards differences in element content of foodstuffs or diets due to the use of different cultivation systems, and differences between harvest years exceeded those seen between cultivation methods. Also, no significant differences in the retention of elements in rats fed diets derived from different cultivation systems were seen, since higher intake resulted in correspondingly higher excretion. CONCLUSION: This study does not support the belief that organically grown foodstuffs generally contain more major and trace elements than conventionally grown foodstuffs, nor does there appear to be an effect on the bioavailability of major and trace minerals in rats. Copyright © 2008 Society of Chemical Industry     

Influence of manufacturing conditions and discrimination of Northern Spanish cheeses using multi‐element analysis

Thirty‐three samples of cheeses belonging to different Protected Designation of Origin (PDOs) located in Northern Spain were analysed with the aim of studying the influence of processing conditions on the minerals and trace elements content in cheeses. The use of sheep milk, animal rennet, salting by immersion in a brine bath and ripening in cheeses reported, in general, the highest levels of trace elements. Moreover, pattern recognition analysis of multi‐elemental data, based on mineral and trace element content, was used to determine geographical traceability and to detect possible imitations with a correct classification in 98.5% of cases.     

Bioavailability of dietary minerals to humans: the stable isotope approach

A number of minerals contained in foods are essential nutrients for humans, animals, and/or plants. While most vitamins are very well absorbed, most essential minerals are not. Usual absorption of minerals ranges from less than 1% to over 90%. The bioavailability of dietary minerals must be considered when determining whether the diet contains enough, too little, or too much. By using stable isotope tracers as labels, the metabolic fate of minerals in a specific day's diet, a specific meal, or a food can be distinguished from minerals from other sources and followed. A number of mass spectrometric methods have been used to measure stable isotopes. Magnetic sector, thermal ionization mass spectrometry (TIMS) is used routinely in our laboratory to study bioavailability of Zn, Cu, and Fe. Other mass spectrometric methods that are less precise, but useful for many applications requiring isotopic determinations include quadrupole TIMS, inductively coupled plasma mass spectrometry (ICP/MS), and fast atom bombardment mass spectrometry (FAB/MS). One of the major advantages of stable isotope studies is that multiple isotopes of the same mineral can be used simultaneously and multiple minerals can be studied simultaneously. The use of stable isotopes for studies of bioavailability of minerals in foods has gained widespread interest in recent years. The approach is expected to be applied to an increasing number of food science and nutrition problems in the future.     

Dietary factors affecting trace element bioavailability from human milk, cow's milk and infant formulas

Bioavailability of trace elements is affected by the type of diet in which they are presented. In general, absorption of the elements iron, zinc, copper, manganese and selenium appears to be higher from human milk than from cow's milk or cow's milk formula while absorption from soy formula appears to be lower than from milk-based products. The effects of individual components such as protein source, carbohydrate, phytate, organic acids and other cations on absorption need to be assessed and the integrated effects of individual dietary components need to be assessed in the intact diet. While ideally absorptive studies should be performed in human infants, there is a need for developing useful and valid models for assessing trace element bioavailability. Increased knowledge about trace element absorption from different infant diets and the factors involved will lead to a better understanding of trace element requirements of infants. This will help in the suggestion of ways to improve means of supplementation.