Zinc supplementation is a critical adjunct therapy for managing acute childhood diarrhoea, particularly in low-income countries (LICs) and lower middle-income countries (LMICs). However, adherence to the recommended zinc regimen remains a major challenge, limiting its effectiveness in real-world settings. This systematic review and meta-analysis aimed to estimate the pooled adherence rates to zinc supplementation for diarrhoea in children under 5 and identify key determinants of adherence. A comprehensive search of PubMed, Embase, Scopus, Google Scholar, ProQuest, and CINAHL was conducted between 2000 and 2024. A total of 10 observational studies were included, with pooled adherence of 63.45% (95% CI: 51.62–75.28) for 10 days regimen and 34.58% (95% CI: 7.08–62.09) for 14 days regimen, along with high heterogeneity. Sensitivity analysis confirmed robustness of these estimates. Key factors associated with adherence included caregiver education, provider counselling, medication acceptability, and economic constraints related to caregiver buying capacity. Doi plot asymmetry suggested possible publication bias for 10 and 14 days regimen. Overall, adherence to zinc therapy remains sub-optimal, particularly for 14 days regimen compared to 10 days regimen. Targeted interventions addressing behavioural, provider, and formulation related barriers are urgently needed to optimize zinc adherence and improve diarrhoea outcomes globally.

Masters athletes tend to have higher intakes of calcium, magnesium, iron, and zinc when compared to Australian national population data from similar age groups(1). However, little is known about the diets of New Zealand Olympians as they get older. This study aimed to describe the micronutrient intakes of New Zealand Olympic and Commonwealth Games athletes over the age of 60 years and make comparisons with National Nutrition Survey data. Thirty-three individuals (mean age 76±8 years, n=27 male) who had represented New Zealand at an Olympic or Commonwealth Games participated in this study. Dietary intake was assessed using three 24-h diet recalls. The first recall was conducted face to face in the participant’s home and the second and third were completed over a voice or video call on non-consecutive days following this. All recalls were performed using a multiple-pass technique and entered into FoodWorks dietary analysis software (Version 9, Xyris Software Ltd., Brisbane, Australia). Mean intakes across the three recalls were used to represent the intake of each individual.This study was approved by the University of Otago Ethics Committee (Health; H23/054, April 2023).The mean intakes of iron (males 13.3±5.1 mg, females 9.9±1.9 mg) and zinc (males 10.7±4.0 mg, females 9.6±1.9 mg) in Olympians were similar to those reported in those over 70 y in the 2008/09 New Zealand Adult Nutrition Survey, but more than 60% of Olympians had intakes below the estimated average requirements for these nutrients. Intakes of calcium (males 1048±474 mg, females 810±139 mg) and selenium (males 66.7±49.1 µg, females 48.4±17.7 µg) were higher in Olympians when compared to the 2008/09 New Zealand Adult Nutrition Survey data, however 39% and 61% of Olympians still had intakes below the estimated average requirements, respectively. While this group of older New Zealand Olympians did have higher intakes of some nutrients than a representative sample of their peers, a marked number are still at risk of inadequate intakes and may benefit from a nutrition intervention to improve the overall quality and adequacy of their diet.

Entomophagy (eating edible insects) could potentially address human deficiencies of iron, zinc and vitamin B12. This article aims to summarise available evidence about the iron, zinc and vitamin B12 content of raw and processed edible insects and compare these with the nutritional needs of different human life stages. A systematic literature search using specific keywords (edible insects, iron content, zinc content, vitamin B12 content and nutritional composition) in Web of Science and Scopus databases was performed. Forty-six studies were reviewed. To ensure standardised comparisons, articles with nutrient-enriched edible insects were excluded. The quality of records was assessed using standardised protocols. Results indicate that edible insects are generally either ‘sources of’ or ‘rich in’ iron, zinc and vitamin B12 required for optimal nutrition and health of different human life stages. Moreover, iron, zinc and vitamin B12 contents of edible insect species were generally either comparable to or higher than that of (lean) beef, (lean) pork, poultry and kidney beans. Most insect species were oven processed with little/no species-specific data for other processing methods. Variations in micronutrient content existed between processing methods and among oven-processed edible insects. Data inaccuracies, poor data quality control and lack of insect-specific official analytical methods contributed to fairly high variations and made comparisons difficult. Based on available data, edible insects can potentially address human deficiencies of iron, zinc and vitamin B12 despite the observed variations, data gaps and lack of edible insect matrix-specific official methods, in addition to limited human bioavailability and efficacy studies.

Children and adolescents diagnosed with autism spectrum disorder (ASD) present feeding problems that may influence food acceptance and refusal. However, data regarding dietary intake variability in this population are either not available in the literature or not well-known. This cross-sectional study aimed to identify the within-person and between-person variability, and the number of days needed for a 24-hour recall (24HR) to estimate the usual intake of children and adolescents with ASD. Data were collected from 284 patients assisted at a public neuropediatric health service in the city of Pelotas, Southern Brazil. Food consumption was assessed using three non-consecutive 24HR. Within-person (S2w) and between-person (S2b) variances, the variance ratio (VR) and the distribution of energy, macronutrients and micronutrients were obtained using the Multiple Source Method® (version 1.0.1). The number of days of 24HR needed was calculated for correlation coefficients of 0·7, 0·8 and 0·9. For most nutrients, S2w was greater than S2b, resulting in VR > 1, except for age-group analyses where children up to 5 years old showed VR < 1. Two to three days of 24HR were estimated for most nutrients, considering a correlation coefficient of 0·8. Differences were observed according to sex and age group, with adolescents requiring more days of 24HR. These findings indicate the need to assess dietary variability among individuals with ASD according to the characteristics of this investigated population.

The present study investigated whether dietary n-3 very-long-chain PUFA (n-3 VLC-PUFA) could increase skin and bone mineralisation in Atlantic salmon (Salmo salar) in vivo and examined their potential effects on human osteoblast proliferation and differentiation in vitro. Atlantic salmon were fed different dietary levels of n-3 VLC-PUFA, and changes in tissue n-3 VLC-PUFA composition, skeletal morphology, skin and bone mineral content, bone mineral density (BMD) and gene expression patterns were examined. Additionally, in vitro experiments using human foetal osteoblast cells were conducted to investigate the potential influence of n-3 VLC-PUFA supplementation on cell proliferation, osteogenic differentiation and cytokine expression. The results demonstrated that increasing the dietary levels of n-3 VLC-PUFA increased the mineral content of vertebrae and BMD in salmon, with subtle yet significant impacts on the expression of genes involved in bone-related processes. Furthermore, in vitro experiments showed a potential contextual influence of n-3 VLC-PUFA supplementation on gene expression of osteogenic markers and cytokine expression. Our findings indicate for the first time that n-3 VLC-PUFA may influence processes related to bone mineralisation.

Selenium (Se) deficiency among populations in Ethiopia is consistent with low concentrations of Se in soil and crops that could be addressed partly by Se-enriched fertilisers. This study examines the disease burden of Se deficiency in Ethiopia and evaluates the cost-effectiveness of Se agronomic biofortification. A disability-adjusted life years (DALY) framework was used, considering goiter, anaemia, and cognitive dysfunction among children and women. The potential efficiency of Se agronomic biofortification was calculated from baseline crop composition and response to Se fertilisers based on an application of 10 g/ha Se fertiliser under optimistic and pessimistic scenarios. The calculated cost per DALY was compared against gross domestic product (GDP; below 1–3 times national GDP) to consider as a cost-effective intervention. The existing national food basket supplies a total of 28·2 µg of Se for adults and 11·3 µg of Se for children, where the risk of inadequate dietary Se reaches 99·1 %–100 %. Cereals account for 61 % of the dietary Se supply. Human Se deficiency contributes to 0·164 million DALYs among children and women. Hence, 52 %, 43 %, and 5 % of the DALYs lost are attributed to anaemia, goiter, and cognitive dysfunction, respectively. Application of Se fertilisers to soils could avert an estimated 21·2–67·1 %, 26·6–67·5 % and 19·9–66·1 % of DALY via maize, teff and wheat at a cost of US$129·6–226·0, US$149·6–209·1 and US$99·3–181·6, respectively. Soil Se fertilisation of cereals could therefore be a cost-effective strategy to help alleviate Se deficiency in Ethiopia, with precedents in Finland.

Osteoarthritis (OA), a disease with a multifactorial aetiology and an enigmatic root cause, affects the quality of life of many elderly patients. Even though there are certain medications utilised to reduce the symptomatic effects, a reliable treatment method to reverse the disease is yet to be discovered. Zinc is a cofactor of over 3000 proteins and is the only metal found in all six classes of enzymes. We explored zinc’s effect on the immune system and the bones as OA affects both. We also discussed zinc-dependent enzymes, highlighting their significant role in the disease’s pathogenesis. It is important to note that both excessive and deficient zinc levels can negatively affect bone health and immune function, thereby exacerbating OA. The purpose of this review is to offer a better understanding of zinc’s impact on OA pathogenesis and to provide clarity regarding its beneficial and detrimental outcomes. We searched thoroughly systematic reviews, meta-analysis, review articles, research articles and randomised controlled trials to ensure a comprehensive review. In brief, using zinc supplementation in the treatment of OA may act as a doubled-edged sword, offering potential benefits but also posing risks.

Although the relationship between dyslipidaemia (DL) and coronary artery disease (CAD) or between trace minerals intake and CAD is well known separately, the exact nature of this relationship remains unknown. We hypothesize that the relationship between trace mineral intake and CAD may differ depending on whether or not the individual has DL. The present study analysed the relationships among trace mineral intake, DL, and CAD in middle-aged and older adults living in Shika town, Ishikawa prefecture, Japan. This study included 895 residents following the exclusion of those with genetic risk carriers for familial hypercholesterolemia. Trace mineral intake was evaluated using the brief-type self-administered diet history questionnaire. Interactions were observed between DL and CAD with zinc (p = 0.004), copper (p = 0.010), and manganese intake (p < 0.001) in a two-way analysis of covariance adjusted for covariates such as sex, age, body mass index, and current smokers and drinkers. Multiple logistic regression analysis showed that zinc (odds ratio (OR): 0.752; 95% confidence interval (CI): 0.606, 0.934; p = 0.010), copper (OR: 0.175; 95% CI: 0.042, 0.726; p = 0.016), and manganese (OR: 0.494; 95% CI: 0.291, 0.839; p = 0.009) were significant independent variables for CAD in the dyslipidaemic group. The present results suggest that DL with a low trace mineral intake is associated with CAD. Further longitudinal studies are required to confirm this relationship.

Zn- and Ca-adsorption equilibria of five Ca-saturated halloysite samples were measured at equilibrium Zn concentrations up to 10−2 M in 10−4 to 10−2 M CaCl2. The results were interpreted on KCaZn vs. [Zn]/CEC (%) plots, where KCaZn is the selectivity coefficient (= [Zn][Ca]/[Ca][Zn]), Zn and Ca represent the adsorbed species, and CEC is the cation-exchange capacity. All Zn adsorption occurred at cation-exchange sites, and 0.77 to 36.0 meq Zn/100 g clay, which constitutes 9 to 83% of the CEC, was adsorbed with “high selectivities” (KCaZn > 10). The higher values were found for two spherical and one “filmy” halloysites, whereas the lower values were found for two tubular halloysites. The magnitude of their 001 intensity, hydration in interlayer space, CEC, and “free” iron oxide content did not correlate with the selective Zn adsorption, but a good correlation was found between the proportion of “high selectivity” sites for Zn and proportion of “high affinity” sites for H+. The adsorption of Zn at the “high selectivity” sites was not completely reversible, and KCaZn values >1000 were recorded in 0.5 M CaCl2 for Zn which occupied 10–40% of the exchange sites. Selective Zn adsorption decreased with decreasing pH, and all adsorbed Zn was extracted with 0.1 M HCl.

The effect of pH, time and temperature on the interaction of zinc with acid and base saturated dickites has been investigated. Increase in pH resulted in an increase in adsorption of zinc in the higher concentration range. The adsorption increased rapidly and then slowly with increase in the time of interaction. The variation of rate constants and the half times of reaction suggested an exchange process controlled by film and possibly particle diffusion and thereafter fixation processes. The inferences found support from the nature of adsorption isotherms. Temperature affected adsorption with exothermic interactions. The activation energy of adsorption of zinc on Na-dickite was 14.0 kcal mole−1.

Hydrotalcite-like compounds, described by the formula [Zn1-xAlx(OH)2][(CO3)x/2 · nH2O], were prepared by coprecipitation methods at 80°C and characterized by bulk chemical analysis, X-ray powder diffraction (XRD), nuclear magnetic resonance (NMR), and scanning-transmission electron microscopy (STEM). An x value of 0.33 was previously assumed to be an upper limit, but recently, Al-rich hydrotalcite-like compounds have been prepared with x as large as 0.44 by hydrothermal synthesis. In the Zn-Al system, Al-rich hydrotalcite was synthesized at normal pressure by coprecipitation. Zn-Al hydrotalcite-like compounds were obtained in the range of x = 0.3 to 0.4. An Al-rich hydrotalcite-like compound with x = 0.44 was formed in mixtures containing large amounts of a poorly crystalline Zn-Al phase. A continuous contraction of the hydrotalcite-like structure occurred as x increased, both the a and c lattice parameters decreasing for x values as large as 0.44. This study illustrates the advantages of using quantitative analytical electron microscopy with high spatial resolution to complement conventional (and bulk) characterization techniques for correlating structural and compositional characteristics of finely divided materials.

Interactions with bentonite are important in the chemical speciation and fate of heavy metals in soils and other ecosystems. The interactions of Zn with bentonite were studied using X-ray diffraction (XRD), dehydration, kinetic and sequential extraction procedures. The species and activity of Zn retained by bentonite were affected markedly by pH. The Zn(OH)+ was retained by bentonite prepared at pH ≥ 6.9. The extent of dehydration of Zn(OH)+-bentonite was higher than that for Zn-bentonite. At a relative humidity of 55.5%, the basal spacing of the Zn(OH)+-bentonite was from 1.21 to 1.26 nm with 1 water sheet and that of the Zn-bentonite was 1.51 nm with 2 water sheets. The greater affinity of Zn(OH)+ for bentonite than Zn was associated with a lower degree of hydration. When an aqueous suspension of Ca-bentonite was incubated with soluble Zn, the concentration of Zn retained by the Ca-bentonite was linearly related to the square root of time. The rate of the interaction was controlled probably by the interlayer diffusion and subsequently by the diffusion into the ditrigonal cavities in bentonite. The Zn retained by bentonite was dehydrated in situ so as to increase the bonding of Zn with surfaces of bentonite. With hydrothermal treatment the retained Zn could diffuse easily into the cavities and transform increasingly to the residual forms that are associated with the entrapped form.

Age-related macular degeneration (AMD) is one of the most prevalent eye diseases among the ageing population worldwide. It is a leading cause of blindness in individuals over 55, particularly in industrialised Western countries. The prevalence of AMD increases with age, and genetic factors and environmental influences are believed to contribute to its development. Among the environmental factors, diet plays a significant role in AMD. This review explores the association between dietary components, dietary patterns and AMD. Various nutrients, non-nutrient substances and dietary models that have the potential to counteract oxidative stress and inflammation, which are underlying mechanisms of AMD, are discussed. Consuming fruits, vegetables, fish and seafood, whole grains, olive oil, nuts and low-glycaemic-index foods has been highlighted as beneficial for reducing the risk of AMD. Adhering to the Mediterranean diet, which encompasses these elements, can be recommended as a dietary pattern for AMD. Furthermore, the modulation of the gut microbiota through dietary interventions and probiotics has shown promise in managing AMD.

Exploring the nutritional potential of underutilized legumes such as Dolichos bean (Lablab purpureus L.) is of great significance, particularly, in view of accomplishing the United Nation's Sustainable Development Goal number two, which emphasizes on improving food and nutrition security by 2030. A thorough understanding of genetic variability is crucial for developing biofortified cultivars of Dolichos bean. In this study, the Dolichos bean genotypes represented by pole and bush types (28 bush and 19 pole types) were assessed for genetic variability for Cu, Mn, Fe and Zn contents. Pole type genotypes had higher average contents for all micronutrients except manganese. Among micronutrients, Cu, Fe, Mn and Zn, content ranged from 10.10–19.95, 77.13–331.93, 22.78–46.40 and 42.03–102.85 mg kg−1 in pole type, and 8.2–18.5, 50.8–99.3, 25.65–53.25 and 37.15–63.25 mg kg−1 in bush type beans, respectively. Strong positive correlations between Cu, Fe and Zn concentrations occurred, which indicates the possibility of simultaneous improvement of these nutrients. Pod pigmentation was positively correlated with contents of Fe and Zn. There was an association of micronutrients with yield. The pole genotypes VRSEM-1000, VRDB-01 and VRSEM 109 and bush type genotypes VRBSEM-3, VRBSEM-35 and VRBSEM- 200 are good source of microelements and high yielders. Gene sources with enhanced nutrients may be used as cultivated forms or as input material for breeding nutritionally rich biofortified varieties of bean.

Hydrotalcite minerals are layered double hydroxides (LDH) which play an important role in immobilizing hazardous compounds to decontaminate industrial wastewaters. The stability of an LDH is mostly evaluated in terms of its low solubility in water. However, the solubility of divalent trace metals immobilized by Mg-Al-type LDHs is not well known. Hydrotalcites containing Zn in solid solution, (Mg+Zn)3-Al-LDH, were synthesized by alkaline co-precipitation. A series of eleven LDH phases with Zn mole fractions XZn = Zn/(Mg+Zn) of 0–1 were characterized by powder X-ray diffractometry (XRD), Fourier-transform infrared (FTIR) spectroscopy, thermogravimetry (TGA), scanning and transmission electron microscopy (SEM/TEM), Brunauer-Emmett-Teller (BET) surface area analysis, and inductively coupled plasma mass (ICP-MS) spectrometry. The XRD analysis provided sharp characteristic spacings for d003 and d006 which occurred for all samples, confirming a layered LDH structure. Cell parameters (a, c) obeyed Vegard’s law and confirmed the formation of a regular solid-solution series without a mixing gap. An aqueous equilibrium time was determined by kinetic dissolution experiments. Steady-state solubility occurred after 120 days, but the experiments continued up to 240 days. The XRD and SEM/TEM analyses indicated no phase changes during the long-term dissolution experiments; neither were phase impurities detected after 240 days. The solubility products of the Mg- and Zn-bearing endmember compositions were calculated from experimentally determined total cation and anion concentrations using the Visual Minteq code for considering element speciation and ion pairing. The solubility product decreased as the Zn mole fraction increased, suggesting that the Zn-bearing LDH phases were more stable than the pure Mg3-Al-LDHs. Solid-solution aqueous-solution thermodynamic equilibrium modeling using the Lippmann “total solubility product” approach and applying Lippmann diagrams with logarithmic x-axes revealed a log-linear decrease in aqueous Zn solubility. The results are promising for remediation of metal-bearing liquid wastes because the metals that co-precipitated with the LDH were more strongly retained and, therefore, less soluble than the hydroxides or carbonates of the trace metal.

Stevensite-like sauconite, with the general composition: ${\text{Si}}_4\left({\text{Zn}}_{3-x}{\square }_x\right){\text{O}}_{10}{\left(\text{OH}\right)}_2{R}_{2x}^{+}$\$\end{document}, where □ is a vacant site, was synthesized. The objective was to study the possible migration of some cations (Li+ and Zn2+) within such trioctahedral smectites, under heating, following the so-called ‘Hofmann-Klemen’ (HK) effect. The initial gel was divided into five aliquots and placed in teflon-coated hydrothermal reactors with distilled water, and these were hydrothermally treated at 80, 100, 120, 150, and 200°C, respectively, over 30 days. X-ray diffraction (XRD) analysis confirmed that the samples synthesized were smectites. The number of vacant sites (x) per half unit cell (O10(OH)2) ranged from nearly 0 to 0.23 but no simple relationship was established between x and the temperature of synthesis. The samples were Li+- and Zn2+-saturated, and heated overnight at 300°C (HK treatment). Cation exchange capacity measurements were made by Fourier transform infrared spectroscopy (FTIR) on ${\text{NH}}_4^{+}$\$\end{document}-saturated samples. After LiHK treatment, the structural formula of samples could be expressed as: ${\text{Si}}_4{\text{Zn}}_{\left(3-x\right)}{\text{Li}}_x{\text{O}}_{10}{\left(\text{OH}\right)}_2{\text{NH}}_{4x}^{+}$\$\end{document}, while after ZnHK treatment, it could be expressed as: Si4Zn3O10(OH)2. Analysis by XRD and FTIR showed that the samples moved from a Zn-stevensite-like structure to Zn-talc-like structure after treatment with ZnHK. These results are interpreted asevidence that Zn2+ (and Li+) migrated into the previously vacant sites under HK treatment.

Hydrotalcite-like layered double hydroxides (LDH), of the formulation M2Al(OH)6(CO3)0.5.H2O, where M = Mg, Zn, Co, Ni, have been prepared, the products characterized and their solubility products measured at ionic strengths of 0.0065 and 0.0128 M and at 25°C. Steady-state solubility was reached after 100 days. The solubility products have been formulated according to the following reaction: $M_2\text{Al}{\left(\text{OH}\right)}_{6}0.5{\text{CO}}_3\cdot {\text{H}}_2\text{O}+6{\text{H}}^{+}\to 2M^{2+}+{\text{Al}}^{3+}+0.5{\text{CO}}_3^{2-}+{\text{H}}_2\text{O}$ where

$K_{\text{SO}}=\frac{{\left[M^{2+}\right]}^2\left[{\text{Al}}^{3+}\right]{\left[{\text{CO}}_3^{2-}\right]}^{0.5}}{{\left[\text{H}\right]}^6}$

Average values of Kso for I = 0, estimated using the Davies equation, are 25.43, 20.80, 22.88 and 20.03 for Mg, Zn, Co and Ni, respectively. Model calculations reveal that the thermodynamic stability of the LDHs is greater than that of the corresponding divalent hydroxides for Zn, Co and Ni below a pH of ∼10, 9 and 8, respectively, and at least up to pH 12 for Mg.

The increasing levels of industrial wastewater released to the environment present a serious threat to human health, living resources, and ecological systems. Fe-modified zeolites were developed and tested for removal of Cu2+ and Zn2+ from contaminated water. The surfaces of the naturally occurring zeolite, clinoptilolite, were modified with Fe(III) oxyhydroxides using three different methods, denoted I, II, and III (FeCli1, FeCli2, and FeNaCli1, respectively). The oxyhydroxides were prepared in Method I using 0.1 M FeCl3·6H2O in an acetate buffer (pH = 3.6); in Method II, using 10ai] FeCl3·6H2O solution in 0.1 M KOH (pH = 10); and Method III was the same as Method I except the clinoptilolite was pretreated with NaCl. Newly synthesized materials from these three methods were then tested for their ability to enhance the sorption capacity for Cu and Zn compared to the natural sample (Cli). Powder X-ray diffraction measurements and the chemical composition of these modified samples confirmed that clinoptilolite maintained its structure while amorphous Fe3+ species were synthesized. The specific surface area (BET method) of both the natural and modified clinoptilolite increased by 2 and 7.5 times for Methods I and II, respectively. Scanning electron microscopy and energy dispersive X-ray spectroscopy revealed that CaO was formed during Method I (FeClii). Throughout the adsorption process, the hydrolysis of CaO and the release of OH− caused the precipitation of Cu and Zn hydroxide, which made the determination of the sorption capacity of FeClii impossible. This phenomenon was avoided in Method III (FeNaClii) because of the absence of exchangeable Ca2+. The adsorption experiments with Method II resulted in double-enchanced adsoprtion capacity. Laboratory batch experiments revealed that the sorption capacities increased in the following order: Cli < FeCli2 < FeNaCli1, for Cu: 0.121 mmol/g < 0.251 mmol/g < 0.403 mmol/g and for Zn: 0.128 mmol/g < 0.234 mmol/g < 0.381 mmol/g.

There is a clear gap in the understanding of the desorption patterns of metals sorbed on soils and clays, despite their importance in the mobility, transport and fate of metals in natural environments. In this study, we investigated the desorption behavior of Cd, Zn and Pb sorbed on montmorillonite (Mt) and on hydroxyaluminum (HyA)- and hydroxyaluminosilicate (HAS)-Mt complexes. At pH 6.5, 2.5 g L–1 of HyA-Mt and HAS-Mt sorbed almost all of the 10–6 M Cd, Zn or Pb, while Mt under the same condition sorbed ~48, 49 and 55% of the added Cd, Zn and Pb, respectively. Based on pH50 values, the selectivity of metal sorption on Mt was Pb > Zn > Cd, and on the complexes, it was Pb ≫ Zn = Cd. In general, larger fractions of sorbed metals were remobilized from Mt than from the complexes. Again, in comparison with Pb, larger fractions of sorbed Cd and Zn were remobilized from different clays. Reducing the pHs of the equilibrium sorption systems from a fixed point (6.5) to different points (6.0, 5.5, 5.0, 4.5, and 4.0) and from different points (6.5, 6.0, 5.5, 5.0, and 4.5) to a fixed point (4.0) both yielded hysteretic metal desorption patterns. The fractions of Cd and Zn desorbed through Na and Cu exchange from the clays, especially from the complexes, were very different, indicating the existence of cation exchangeable metal sorption sites of weak and strong affinities on the complexes. Based on the EDTA-extractable fractions of Cd and Zn from HAS–Mt and HyA-Mt, it appeared that HyA–metal bonds are stronger than the HAS–metal bonds. Compared with other agents, acetic acid remobilized the highest fractions of all metals irrespective of the type of clays, with a concomitant release of Al or Al + Si. The Pb-HyA/HAS-Mt bonds were, however, still much too strong to be broken substantially by this mechanism. The results accomplished in this study suggest further attention to the fundamental understanding of the mobility, fate, bioavailability and toxicity of the concerned metals in soils and related environments.