Zn2+ regulates human oxalate metabolism by manipulating oxalate decarboxylase to treat calcium oxalate stones

A high concentration of oxalate is associated with an increased risk of kidney calcium oxalate (CaOx) stones, and the degradation of exogenous oxalate mostly depends on oxalate-degrading enzymes from the intestinal microbiome. We found that zinc gluconate supplement to patients with CaOx kidney stones could significantly improve the abundance of oxalate metabolizing bacteria in humans through clinical experiments on patients also subjected to antibiotic treatment. The analysis of clinical samples revealed that an imbalance of Lactobacillus and oxalate decarboxylase (OxDC) was involved in the formation of CaOx kidney stones. Then, we identified that Zn²⁺ could be used as an external factor to improve the activity of OxDC and promote Lactobacillus in the intestinal flora, and this treatment achieved a therapeutic effect on rats with stones aggravated by antibiotics. Finally, by analyzing the three-dimensional structure of OxDC and completing in vitro experiments, we propose a model of the Zn²⁺-induced reduction of CaOx kidney stone symptoms in rats by increasing the metabolism of oxalate through the positive effects of Zn²⁺ on Lactobacillus and OxDC.

Novel and safe debranched starch-zinc complexes with endoconcave structure as zinc supplements

Zinc deficiency is a serious risk to human health and growth, especially in children. The development of zinc supplements can effectively reduce this harm. Here, a series of debranched starch‑zinc complexes (DS-Zn) were prepared, whose zinc complexation was inversely proportional to the amylopectin content in the debranched starch (DS). The physicochemical properties of DS-Zn were characterized using the conductivity, XRD, iodine staining and thermogravimetry. Combined with XPS, solid-state 13C NMR and IR, it was elucidated that the structure of DS-Zn is endoconcave structure with 2-O and 3-O of DS on the inner side and 6-O of DS on the outer side, where zinc is located. The DS-Zn exhibits good biosafety including blood, cellular and mutagenicity. In vitro simulations of digestion and zinc-deficient cellular models showed that DS-Zn was more tolerant to the gastrointestinal environment and more effective in zinc supplementation (increased by 33 %) than inorganic zinc supplements. Utilizing the compressibility of starch, DS-Zn was prepared as a more palatable oral cartoon tablet for children. This study will provide important support to advance the development and application of novel starch-based zinc nutritional supplements.

A Meta-analysis of Responses of Broiler Chickens to Dietary Zinc Supplementation: Feed Intake, Feed Conversion Ratio and Average Daily Gain

The importance of zinc (Zn) in broiler chicken nutrition is gaining attention due to the realization of its role in several enzymes and metabolic functions. This meta-analysis, therefore, aimed to synthesize pooled evidence on the effectiveness of Zn supplementation on enhancing feed intake, feed conversion ratio (FCR) and average daily gain (ADG) in broiler chickens. Thirty-seven peer-reviewed studies out of 436 identified from the search carried out in Scopus, Google Scholar and PubMed databases met the criteria for inclusion in this meta-analysis. Data were pooled and then disaggregated for moderators: broiler strains, sources of Zn, duration of Zn supplementation and Zn supplementation levels. All the analyses were conducted in Open Meta-analyst for Ecology and Evolution (OpenMEE) software. Pooled results indicate that Zn supplementation increased feed intake [standardised mean differences (SMD) = 0.34 g/bird/day; 95% confidence interval (CI) 0.27, 0.42)] and ADG (SMD = 0.43 g/bird/day; 95% CI 0.35, 0.50) in broiler chickens in comparison with the controls. Dietary Zn supplementation improves FCR (SMD =  - 0.16 g/g; 95% CI 0.20, - 0.11), taking heterogeneity and publication biases into account. Restricted subanalysis showed that studied moderators influenced the outcomes of the meta-analysis. Meta-regression revealed that moderators explain about 38% of the sources of variations in the present study. This meta-analysis suggests that dietary zinc supplementation had a positive effect on growth performance indices in broiler chickens.