Zinc and diarrheal disease: current status and future perspectives

Mechanism of metal ion-induced cell death in gastrointestinal cancer

Gastrointestinal (GI) cancer is one of the most severe types of cancer, with a significant impact on human health worldwide. Due to the urgent demand for more effective therapeutic strategies against GI cancers, novel research on metal ions for treating GI cancers has attracted increasing attention. Currently, with accumulating research on the relationship between metal ions and cancer therapy, several metal ions have been discovered to induce cell death. In particular, the three novel modes of cell death, including ferroptosis, cuproptosis, and calcicoptosis, have become focal points of research in the field of cancer. Meanwhile, other metal ions have also been found to trigger cell death through various mechanisms. Accordingly, this review focuses on the mechanisms of metal ion-induced cell death in GI cancers, hoping to provide theoretical support for further GI cancer therapies.

Zinc Deficiency and Therapeutic Value of Zinc Supplementation in Pediatric Gastrointestinal Diseases

The benefits of zinc in treating certain gastrointestinal (GI) diseases have been recognized for over two decades. This review aims to explore zinc deficiency (ZD) and the potential therapeutic value and safety of zinc supplementation in pediatric GI diseases. A systematic review of published articles on ZD and zinc as adjuvant treatments for GI diseases was conducted using various databases. Children with inflammatory bowel disease (IBD), celiac disease, and those receiving long-term proton pump inhibitor treatments are particularly susceptible to ZD. ZD in children with celiac disease and IBD is attributed to insufficient intake, reduced absorption, and increased intestinal loss as a result of the inflammatory process. Zinc plays a crucial role in maintaining the integrity of the gastric mucosa and exerts a gastroprotective action against gastric lesions. Although considerable evidence supports the use of zinc as adjuvant therapy for certain GI diseases in adults, its use is unspecified in children except for infectious diarrhea. Current evidence suggests that zinc supplementation with well-documented dosages helps reduce the duration of diarrhea in children with acute or persistent diarrhea, while there are no specific guidelines for zinc supplementation in children with IBD and celiac disease. Zinc supplementation appears to be beneficial in peptic ulcer disease or gastroesophageal reflux disease. The available evidence highlights the need for intervention programs to enhance zinc status and reduce the morbidity of certain GI diseases in children.

Association of Copper and Zinc Intake with Inflammatory Bowel Disease and Fecal Incontinence Symptoms: Evidence from the National Health and Nutrition Examination Survey

The associations between copper and zinc intake with the risk of inflammatory bowel disease (IBD) and fecal incontinence symptoms in the general population are not well understood. This study aims to evaluate the associations of zinc and copper intake with the risk of IBD and fecal incontinence symptoms in adults aged ≥ 20 years using data from the 2009-2010 National Health and Nutritional Examination Surveys (NHANES) (N = 5593). The presence of IBD was analyzed from the NHANES data, directly querying the presence or absence of ulcerative colitis (UC) and Crohn's disease (CD). Fecal incontinence symptoms including accidental bowel leakage of gas, mucus, liquid, or solid stool were determined by using the bowel health questionnaire. Multivariable logistic regressions models were performed controlling for confounding factors (dietary, lifestyle, psychological, and health conditions). No associations between either zinc or copper intake with IBD were found. However, zinc intake was independently associated with increased risk of bowel leakage of gas or liquid. Compared with quartile 1, the multivariate-adjusted ORs (95%CI) of bowel leakage of gas across quartiles 2-4 of zinc intake were 1.41 (1.15-1.71), 1.30 (1.00-1.68), and 1.61 (1.16-2.23). Likewise, there was a trend for higher odds of bowel leakage of liquid among participants in the higher zinc intake. Compared with quartile 1, the multivariate-adjusted ORs (95%CI) of bowel leakage of liquid across quartiles 2-4 of zinc intake were 3.55 (0.94-13.41), 3.65 (1.27-10.47), and 5.06 (1.25-20.50). Future prospective studies are warranted to confirm these findings.

Aetiology of acute diarrhoea and antimicrobial usage among children aged under five years at health centres in Bahir Dar, Ethiopia

The aetiology of diarrhoea with Cryptosporidium species and pathogenic bacteria has not been identified in the Ethiopian primary healthcare system. Thus, antibiotic consumption for unconfirmed pathogenic diarrhoea is not infrequent. A total of 344 children aged <5 years with diarrhoea were included in the present study to determine protozoal or bacterial aetiology and antibiotic use. Overall, 47.1% of children with diarrhoea had either protozoan or bacterial pathogens. The prevalence of Cryptosporidium species was 12.8% while bacterial pathogens were 13.1%. Based on direct microscopic stool examination, 77.6% (267/344) of children with diarrhoea were treated with antimicrobials. Of these, 16.7%-51.4% of prescribed antimicrobials were appropriate. None of the children with Cryptosporidium diarrhoea were treated with the appropriate antimicrobial. Enteric bacterial pathogens showed a resistance of 51.6% to cotrimoxazole. Empirical treatments are not appropriate for the majority of child cases of diarrhoea.

The zinc sensing receptor, ZnR/GPR39, triggers metabotropic calcium signalling in colonocytes and regulates occludin recovery in experimental colitis

Impaired epithelial barrier function is a hallmark of inflammatory bowel diseases, such as colitis, contributing to diarrhoea and perpetuating inflammation. We show that the zinc sensing receptor, ZnR/GPR39, triggers intracellular Ca(2+) signalling in colonocytes thereby inducing occludin expression. Moreover, ZnR/GPR39 is essential for epithelial barrier recovery in the dextran sodium sulfate (DSS) ulcerative colitis model. Loss of ZnR/GPR39 results in increased susceptibility to DSS-induced inflammation, owing to low expression of the tight junction protein occludin and impaired epithelial barrier. Recovery of wild-type (WT) mice from the DSS insult was faster than that of ZnR/GPR39 knockout (KO) mice. Enhanced recovery of the epithelial layer and increased crypt regeneration were observed in WT mice compared with ZnR/GPR39 KO, suggesting that ZnR/GPR39 is promoting epithelial barrier integrity following DSS insult. Indeed, cell proliferation and apical expression of occludin, following the DSS-induced epithelial erosion, were increased in WT tissue but not in ZnR/GPR39 KO tissue. Importantly, survival following DSS treatment was higher in WT mice compared with ZnR/GPR39 KO mice. Our results support a direct role for ZnR/GPR39 in promoting epithelial renewal and barrier function following DSS treatment, thereby affecting the severity of the disease. We suggest ZnR/GPR39 as a novel therapeutic target that can improve epithelial barrier function in colitis.This article is part of the themed issue 'Evolution brings Ca(2+) and ATP together to control life and death'.

Antidiarrheal Drug Therapy

INTRODUCTION

Acute diarrhea often runs a self-limited course and little by way of treatment is needed except for oral rehydration therapy. Chronic diarrhea poses a longer-term problem. If not treatable with specific therapy aimed at the underlying pathophysiology, chronic diarrhea often needs long-term symptomatic therapy.

PURPOSE OF REVIEW

This paper aims to examine the options for symptomatic, nonspecific treatment of diarrhea.

RECENT FINDINGS

The most frequently used therapies are opiate antidiarrheal drugs. These drugs are effective for a wide variety of diarrheal conditions and generally can be used safely if monitored closely. They work by slowing motility and allowing more time for absorption. They vary in potency and in addictive liability. In recent years, a variety of other drugs have been developed, which provide more targeted therapy that can mitigate diarrhea in specific situations. These drugs work on other regulatory pathways in the gut or on mucosal absorptive mechanisms. There is evidence for efficacy for both traditional and newer agents used for the symptomatic management of diarrhea. Opiates are used most often for this indication. Other agents may benefit individuals, but further research is needed to establish indications and best practices.

Assessment of Serum Trace Elements in Diarrheic Yaks (Bos grunniens) in Hongyuan, China

Diarrhea is one of the main causes of animal deaths especially in neonatal calves. The objective of this study was to investigate the blood serum for cobalt (Co), copper (Cu), iron (Fe), magnesium (Mg), manganese (Mn), Molybdenum (Mo), selenium (Se), and zinc (Zn) concentrations in yak serum samples by inductively coupled plasma mass spectrometry (ICP-MS) from 35 yaks consisting of 10 healthy and 25 diarrheic ones. Our observations indicated that the concentrations of Mn, Zn, and Fe in yak affected with diarrhea had statistically significant reduced levels as compared to the control group (P < 0.05). The mean concentration of Cu in blood serum of diarrheic yaks was found significantly higher than the normal ones (P < 0.05). The Mn and Zn in the serum of diarrheic groups were observed significantly different (P < 0.05) with different ages. These findings can provide for some valuable information for the investigation on relationship between trace elements in the serum of normal and diarrheic yaks.

The potential for zinc stable isotope techniques and modelling to determine optimal zinc supplementation

It is well recognised that zinc deficiency is a major global public health issue, particularly in young children in low-income countries with diarrhoea and environmental enteropathy. Zinc supplementation is regarded as a powerful tool to correct zinc deficiency as well as to treat a variety of physiologic and pathologic conditions. However, the dose and frequency of its use as well as the choice of zinc salt are not clearly defined regardless of whether it is used to treat a disease or correct a nutritional deficiency. We discuss the application of zinc stable isotope tracer techniques to assess zinc physiology, metabolism and homeostasis and how these can address knowledge gaps in zinc supplementation pharmacokinetics. This may help to resolve optimal dose, frequency, length of administration, timing of delivery to food intake and choice of zinc compound. It appears that long-term preventive supplementation can be administered much less frequently than daily but more research needs to be undertaken to better understand how best to intervene with zinc in children at risk of zinc deficiency. Stable isotope techniques, linked with saturation response and compartmental modelling, also have the potential to assist in the continued search for simple markers of zinc status in health, malnutrition and disease.

Zinc deficiency alters host response and pathogen virulence in a mouse model of enteroaggregative Escherichia coli-induced diarrhea

Enteroaggregative Escherichia coli (EAEC) is increasingly recognized as a major cause of diarrheal disease globally. In the current study, we investigated the impact of zinc deficiency on the host and pathogenesis of EAEC. Several outcomes of EAEC infection were investigated including weight loss, EAEC shedding and tissue burden, leukocyte recruitment, intestinal cytokine expression, and virulence expression of the pathogen in vivo. Mice fed a protein source defined zinc deficient diet (dZD) had an 80% reduction of serum zinc and a 50% reduction of zinc in luminal contents of the bowel compared to mice fed a protein source defined control diet (dC). When challenged with EAEC, dZD mice had significantly greater weight loss, stool shedding, mucus production, and, most notably, diarrhea compared to dC mice. Zinc deficient mice had reduced infiltration of leukocytes into the ileum in response to infection suggesting an impaired immune response. Interestingly, expression of several EAEC virulence factors were increased in luminal contents of dZD mice. These data show a dual effect of dietary zinc in benefitting the host while impairing virulence of the pathogen. The study demonstrates the critical importance of zinc and may help elucidate the benefits of zinc supplementation in cases of childhood diarrhea and malnutrition.

Zinc treatment ameliorates diarrhea and intestinal inflammation in undernourished rats

BACKGROUND

WHO guidelines recommend zinc supplementation as a key adjunct therapy for childhood diarrhea in developing countries, however zinc's anti-diarrheal effects remain only partially understood. Recently, it has been recognized that low-grade inflammation may influence stunting. In this study, we examined whether oral zinc supplementation could improve weight, intestinal inflammation, and diarrhea in undernourished weanling rats.

METHODS

Rats were undernourished using a northeastern Brazil regional diet (RBD) for two weeks, followed by oral gavage with a saturated lactose solution (30 g/kg) in the last 7 days to induce osmotic diarrhea. Animals were checked for diarrhea daily after lactose intake. Blood was drawn in order to measure serum zinc levels by atomic absorption spectroscopy. Rats were euthanized to harvest jejunal tissue for histology and cytokine profiles by ELISA. In a subset of animals, spleen samples were harvested under aseptic conditions to quantify bacterial translocation.

RESULTS

Oral zinc supplementation increased serum zinc levels following lactose-induced osmotic diarrhea. In undernourished rats, zinc improved weight gain following osmotic diarrhea and significantly reduced diarrheal scores by the third day of lactose intake (p < 0.05), with improved jejunum histology (p < 0.0001). Zinc supplementation diminished bacterial translocation only in lactose-challenged undernourished rats (p = 0.03) compared with the untreated challenged controls and reduced intestinal IL-1β and TNF-α cytokines to control levels.

CONCLUSION

Altogether our findings provide novel mechanisms of zinc action in the setting of diarrhea and undernutrition and support the use of zinc to prevent the vicious cycle of malnutrition and diarrhea.

Extreme population differences in the human zinc transporter ZIP4 (SLC39A4) are explained by positive selection in Sub-Saharan Africa

Extreme differences in allele frequency between West Africans and Eurasians were observed for a leucine-to-valine substitution (Leu372Val) in the human intestinal zinc uptake transporter, ZIP4, yet no further evidence was found for a selective sweep around the ZIP4 gene (SLC39A4). By interrogating allele frequencies in more than 100 diverse human populations and resequencing Neanderthal DNA, we confirmed the ancestral state of this locus and found a strong geographical gradient for the derived allele (Val372), with near fixation in West Africa. In extensive coalescent simulations, we show that the extreme differences in allele frequency, yet absence of a classical sweep signature, can be explained by the effect of a local recombination hotspot, together with directional selection favoring the Val372 allele in Sub-Saharan Africans. The possible functional effect of the Leu372Val substitution, together with two pathological mutations at the same codon (Leu372Pro and Leu372Arg) that cause acrodermatitis enteropathica (a disease phenotype characterized by extreme zinc deficiency), was investigated by transient overexpression of human ZIP4 protein in HeLa cells. Both acrodermatitis mutations cause absence of the ZIP4 transporter cell surface expression and nearly absent zinc uptake, while the Val372 variant displayed significantly reduced surface protein expression, reduced basal levels of intracellular zinc, and reduced zinc uptake in comparison with the Leu372 variant. We speculate that reduced zinc uptake by the ZIP4-derived Val372 isoform may act by starving certain pathogens of zinc, and hence may have been advantageous in Sub-Saharan Africa. Moreover, these functional results may indicate differences in zinc homeostasis among modern human populations with possible relevance for disease risk.

The micronutrient zinc inhibits EAEC strain 042 adherence, biofilm formation, virulence gene expression, and epithelial cytokine responses benefiting the infected host

Enteroaggregative Escherichia coli (EAEC) is a major pathogen worldwide, associated with diarrheal disease in both children and adults, suggesting the need for new preventive and therapeutic treatments. We investigated the role of the micronutrient zinc in the pathogenesis of an E. coli strain associated with human disease. A variety of bacterial characteristics-growth in vitro, biofilm formation, adherence to IEC-6 epithelial cells, gene expression of putative EAEC virulence factors as well as EAEC-induced cytokine expression by HCT-8 cells-were quantified. At concentrations (≤ 0.05 mM) that did not alter EAEC growth (strain 042) but that are physiologic in serum, zinc markedly decreased the organism's ability to form biofilm (P<0.001), adhere to IEC-6 epithelial cells (P<0.01), and express putative EAEC virulence factors (aggR, aap, aatA, virK) (P<0.03). After exposure of the organism to zinc, the effect on virulence factor generation was prolonged (> 3 h). Further, EAEC-induced IL-8 mRNA and protein secretion by HCT-8 epithelial cells were significantly reduced by 0.05 mM zinc (P<0.03). Using an in vivo murine model of diet-induced zinc-deficiency, oral zinc supplementation (0.4 µg/mouse daily) administered after EAEC challenge (10 (10) CFU/mouse) significantly abrogated growth shortfalls (by>90%; P<0.01); furthermore, stool shedding was reduced (days 9-11) but tissue burden of organisms in the intestine was unchanged. These findings suggest several potential mechanisms whereby physiological levels of zinc alter pathogenetic events in the bacterium (reducing biofilm formation, adherence to epithelium, virulence factor expression) as well as the bacterium's effect on the epithelium (cytokine response to exposure to EAEC) to alter EAEC pathogenesis in vitro and in vivo. These effects may help explain and extend the benefits of zinc in childhood diarrhea and malnutrition.

Zinc and other micronutrients supplementation through the use of sprinkles: impact on the occurrence of diarrhea and respiratory infections in institutionalized children

OBJECTIVE

To evaluate the incidence of diarrheal disease (DD) and acute respiratory infection (ARI) in children undergoing supplementation of zinc and other micronutrients through the use of sprinkles, as well as their acceptance by these patients.

METHOD

This was a randomized double-blinded clinical trial of 143 healthy institutionalized children, aged 6 to 48 months. They were randomized into two groups and received daily zinc and micronutrients - test group (sprinkles), or micronutrients without zinc - control group. Children were supplemented for 90 days and followed regarding the outcomes of DD and ARI.

RESULTS

Of the randomized children, 52.45% belonged to the test and 47.55% to the control group. The incidence of DD in the test group was 14.7% and was 19.1% in the control group. The test group showed a lower risk of developing DD when compared to controls, but this finding was not statistically significant (RR=0.77 [0.37 to 1.6], p=0.5088). ARI had high incidence in both groups, 60% in the test group and 48.5% in the control group, with an increased risk of developing the disease in the test group, but with no statistical significance (RR=1.24 [0.91 to 1.68], p=0.1825). Regarding acceptance, the mean percentage of consumption, in days, of the entire content of the sachets containing sprinkles was 95.72% (SD=4.9) and 96.4% (SD=6.2) for the test and control groups, respectively.

CONCLUSIONS

Zinc supplementation through the use of sprinkles did not reduce the incidence of DD or ARI among the evaluated children. The sprinkles were well accepted by all study participants.

Effects of zinc on epithelial barrier properties and viability in a human and a porcine intestinal cell culture model

Zinc is an essential trace element with a variety of physiological and biochemical functions. Piglets are commonly supplemented, during the weaning period, with doses of zinc above dietary requirements with positive effects on health and performance that might be attributed to anti-secretory and barrier-enhancing effects in the intestine. For a better understanding of these observations increasing zinc sulfate (ZnSO4; 0-200μM) concentrations were used in an in vitro culture model of porcine (IPEC-J2) and human (Caco-2) intestinal epithelial cells and effects on barrier function, viability, and the mRNA expression of one selected heat shock protein (Hsp) were assessed. When treated apically with zinc sulfate, the transepithelial electrical resistance (TEER) did not change significantly. In contrast, cell viability measured by lactate dehydrogenase (LDH) leakage, by ATP and by WST-1 conversion in postconfluent IPEC-J2 monolayers was affected after a 24-h treatment with 200μM ZnSO4. Caco-2 cells were more resistant to Zn. ZnSO4 did not induce any effect on viability, except when it was used at the highest concentration (200μM), and only in preconfluent cells. Furthermore, ZnSO4 induced Hsp70 mRNA expression at 200μM and was more pronounced in preconfluent cells. The observed dose-related effects of zinc are cell-line specific and depended on the differentiation status of the cells. The IPEC-J2 cell line appears to be a suitable in vitro model to characterize specific effects on porcine intestinal cells.

Role of zinc in pediatric diarrhea

Zinc supplementation is a critical new intervention for treating diarrheal episodes in children. Recent studies suggest that administration of zinc along with new low osmolarity oral rehydration solutions / salts (ORS), can reduce the duration and severity of diarrheal episodes for up to three months. The World Health Organization (WHO) and UNICEF recommend daily 20 mg zinc supplements for 10 – 14 days for children with acute diarrhea, and 10 mg per day for infants under six months old, to curtail the severity of the episode and prevent further occurrences in the ensuing -two to three months, thereby decreasing the morbidity considerably. This article reviews the available evidence on the efficacy and safety of zinc supplementation in pediatric diarrhea and convincingly concludes that zinc supplementation has a beneficial impact on the disease outcome.

Childhood diarrhoea: failing conventional measures, what next?

BACKGROUND

Diarrhoea is one of the leading causes of infant mortality. This article analyzes its contribution towards the realization of millennium development goal number 4 (MDG-4).

METHODS

A PubMed search using keywords acute infant diarrhea together with prevalence, management, or prevention 23 of the 634 generated articles were reviewed for inclusion.

RESULTS

WHO first expressed concern about diarrhoeal mortality in 1979. Two decades later it reported diarrhoea as the second leading cause of infant mortality worldwide. The annual death toll of 1.5 million is greater than AIDS, malaria and measles combined. Short term repercussions (dehydration, electrolyte imbalance, malnutrition, shock, death) plus long-term diminished fitness index, cognitive function, and school performance have major impact on society. Ever since its 1971 success, Oral Rehydration Therapy has been the cornerstone treatment of diarrhoea. Decreased compliance has been recorded worldwide with Kenya ranking first. Intravenous therapy is useful in preventing complications while anti-diarrhoeals and anti-microbials, are indicated in severe cases. Zinc supplementation has also proven effective, and is recommended along with rehydration. Furthermore, immunization and good hygiene prevent faecal-oral transmissions.

CONCLUSION

MDG-4 aims to reduce childhood mortality by 2/3 by 2015. Studies, however, show minimal progress, and the target is likely to be missed. Efforts must therefore be made to review existing strategies and formulate newer ones. Research priorities need to move away from perceived 'killer diseases' since far more children die in a day than have ever died from avian influenza for example.

Recent Advances of Oral Rehydration Therapy (ORT)

Diarrheal disease is one of the leading causes of worldwide morbidity and mortality, especially in children. It causes loss of body fluid, which may lead to severe dehydration, electrolyte imbalance, shock and even to death. The mortality rate from acute diarrhea has decreased over the last few decades. This decline, especially in developing countries is largely due to the implantation of the standard World Health Organization-oral rehydration solution (WHO-ORS). However, the use of standard ORS has been limited by its inability to reduce fecal volume or diarrhea duration. Subsequently, this has led to various attempts to modify its compositions. And these modifications include the use of reduced osmolarity ORS, polymer-based ORS and zinc supplementation. Some of these variations have been successful and others are still under investigation. Therefore, further trials are needed to progress toward the ideal ORS. In this article, we briefly reviewed the pathophysiologic basis of the ORS, followed by the standard WHO-ORS and several modifications to improve the ORS.

The traditional antidiarrheal remedy, Garcinia buchananii stem bark extract, inhibits propulsive motility and fast synaptic potentials in the guinea pig distal colon

BACKGROUND

Garcinia buchananii bark extract is a traditional African remedy for diarrhea, dysentery, abdominal discomfort, and pain. We investigated the mechanisms and efficacy of this extract using the guinea pig distal colon model of gastrointestinal motility.

METHODS

Stem bark was collected from G. buchananii trees in their natural habitat of Karagwe, Tanzania. Bark was sun dried and ground into fine powder, and suspended in Krebs to obtain an aqueous extract. Isolated guinea pig distal colon was used to determine the effect of the G. buchananii bark extract on fecal pellet propulsion. Intracellular recording was used to evaluate the extract action on evoked fast excitatory postsynaptic potentials (fEPSPs) in S-neurons of the myenteric plexus.

KEY RESULTS

Garcinia buchananii bark extract inhibited pellet propulsion in a concentration-dependent manner, with an optimal concentration of ∼10 mg powder per mL Krebs. Interestingly, washout of the extract resulted in an increase in pellet propulsion to a level above basal activity. The extract reversibly reduced the amplitude of evoked fEPSPs in myenteric neurons. The extract's inhibitory action on propulsive motility and fEPSPs was not affected by the opioid receptor antagonist, naloxone, or the alpha- 2 adrenoceptor antagonist, yohimbine. The extract inhibited pellet motility in the presence of gamma-aminobutyric acid (GABA), GABA(A) and GABA(B) receptor antagonists picrotoxin and phaclofen, respectively. However, phaclofen and picrotoxin inhibited recovery rebound of motility during washout.

CONCLUSIONS & INFERENCES

Garcinia buchananii extract has the potential to provide an effective, non-opiate antidiarrheal drug. Further studies are required to characterize bioactive components and elucidate the mechanisms of action, efficacy, and safety.

Acute and persistent diarrhea

Socially disadvantaged Indigenous infants and children living in western industrialized countries experience high rates of infectious diarrhea, no more so than Aboriginal children from remote and rural regions of Northern Australia. Diarrheal disease, poor nutrition, and intestinal enteropathy reflect household crowding, inadequate water and poor sanitation and hygiene. Acute episodes of watery diarrhea are often best managed by oral glucose-electrolyte solutions with continuation of breastfeeding and early reintroduction of feeding. Selective use of lactose-free milk formula, short-term zinc supplementation and antibiotics may be necessary for ill children with poor nutrition, persistent symptoms, or dysentery. Education, high standards of environmental hygiene, breastfeeding, and immunization with newly licensed rotavirus vaccines are all needed to reduce the unacceptably high burden of diarrheal disease encountered in young children from Indigenous communities.

Oral rehydration solutions in non-cholera diarrhea: a review

The use of oral rehydration solution (ORS) has revolutionized the management of acute diarrhea. The implementation of the standard World Health Organization ORS (WHO-ORS) has resulted in decreased mortality associated with acute diarrheal illnesses in children, although in general stool volume and diarrhea durations are not reduced. Decreased morbidity and mortality have occurred because of improved hydration status. Decreased morbidity has also been described in adults who used this therapy. Various modifications to the standard ORS have been derived. These modifications have included hypo-osmolar or hyperosmolar solutions, use of rice-based ORS, zinc supplementation, and the use of amino acids, including glycine, alanine, and glutamine. Some of these variations have been successful, some have not, and others are still under investigation. ORS has been used for travelers' diarrhea and to decrease intravenous (IV) fluid requirements in patients with short bowel syndrome (SBS) who require parenteral nutrition (PN). This paper reviews the standard WHO-ORS and its mechanism of action, followed by more contemporary reduced osmolarity ORS and rice-based ORS in non-cholera diarrhea. Various modifications to improve ORS are also discussed.

Zinc deficiency

PURPOSE OF REVIEW

Zinc plays an essential role in numerous biochemical pathways. Zinc deficiency affects many organ systems, including the integumentary, gastrointestinal, central nervous system, immune, skeletal, and reproductive systems. This article aims to discuss zinc metabolism and highlights a few of the diseases associated with zinc deficiency.

RECENT FINDINGS

Zinc deficiency results in dysfunction of both humoral and cell-mediated immunity and increases the susceptibility to infection. Supplementation of zinc has been shown to reduce the incidence of infection as well as cellular damage from increased oxidative stress. Zinc deficiency is also associated with acute and chronic liver disease. Zinc supplementation protects against toxin-induced liver damage and is used as a therapy for hepatic encephalopathy in patients refractory to standard treatment. Zinc deficiency has also been implicated in diarrheal disease, and supplementation has been effective in both prophylaxis and treatment of acute diarrhea.

SUMMARY

This article is not meant to review all of the disease states associated with zinc deficiency. Rather, it is an introduction to the influence of the many roles of zinc in the body, with an extensive discussion of the influence of zinc deficiency in selected diseases. Zinc supplementation may be beneficial as an adjunct to treatment of many disease states.