Enhancing delivery of minerals using multifunctional carriers

近年来，由于久坐不动的生活方式导致能量摄入减少，许多矿物质和维生素的摄入量已经下降。人们还认识到，这些营养素对最佳健康和减少慢性饮食相关疾病风险的需求可能高于为避免缺乏症而建议的需求。在像英国这样的工业化国家，缺铁仍然是一种相对常见的营养失调，特别是对于那些由于生长、失血或老年而需要高铁的人。铁、钙、锌和镁等矿物质的吸收往往因与其他膳食成分（如植酸盐和单宁）结合或氧化成不溶性形式而减少，从而严重减少吸收。因此，矿物质的吸收和吸收强烈地依赖于它们的形式。因此，如果有可能设计一种系统，在加工、储存和消化（胃）的早期阶段保护矿物质，然后将矿物质释放到小肠中，在那里它被身体吸收，我们应该能够增强矿物质的吸收。因此，该项目的目的是开发一种新的水溶性矿物质递送结构，该结构对与消化过程相关的pH值变化敏感。矿物（在这个项目中，我们将重点放在铁上）被安置在小凝胶微珠中(大约。0.1毫米直径)。这些珠子被生物聚合物层和不透水的脂质或蜡层包裹。生物聚合物是常用的食品成分，如果胶和蛋白质，当在这些结构中组装时，对pH值变化变得敏感。我们已经证明，它们在胃中遇到的酸性pH值下是稳定的，但当进入与小肠相关的较高pH值时，它们会降解。不可渗透的脂质层将被十二指肠中的酶降解，从而使铁从微球中释放出来，从而可供吸收。该项目被划分为若干任务，以实现以下主要目标。1. 创建和表征生物聚合物层的pH值和环境敏感性。利用可以测量这些分子层的质量和组成的技术，我们可以确定这些层对pH值变化的反应，并选择合适的系统。2. 组装微珠并涂上选定的生物聚合物层。在这里，我们将开发方法，使我们能够在不渗透的生物聚合物层中封装铁负载微珠。3. 测定稳定性、包封效率和铁释放性能。我们将测量在典型的加工和储存条件下，以及在模拟消化过程中，有多少铁从微珠中逸出，以确保它们在适当的条件下释放铁。我们还将利用细胞培养研究来观察释放出来的铁是否能被小肠内壁的细胞吸收。4. 测定从包覆的微珠中吸收铁的速率。装有微球的食物将被喂给人类志愿者，他们的血浆铁浓度将被监测。这将揭示这些结构在促进铁的输送方面究竟有多有效。如果成功，这个项目的结果可以应用于其他矿物质和水溶性营养素，其中强化是一个问题。这些方法可以广泛应用于各种食物，从而有助于增加这些重要膳食成分的摄入量。

The intake of many minerals and vitamins has fallen in recent years, due to reduced energy intake associated with a more sedentary lifestyle. It is also recognised that requirements of these nutrients for optimal health and reduction in the risk of chronic diet-related diseases may be higher than those recommended to avoid deficiency disorders. In industrialised countries such as the UK, iron deficiency is still a relatively common nutritional disorder, especially in individuals with a high requirement due to growth, blood loss or in old age. The absorption of minerals such as iron, calcium, zinc and magnesium is often reduced due to binding with other dietary constituents such as phytates and tannins, or oxidation into insoluble forms which severely reduce uptake. Therefore the absorption and uptake of minerals are strongly dependent on the form they are in. Therefore if is possible to design a system that will protect the mineral during processing, storage and the early stages of digestion (stomach), and then release the mineral into the small intestine, where it is absorbed by the body, we should be able to enhance mineral uptake. The aim of this project is therefore to develop a novel delivery structure for water soluble minerals that is sensitive to changes in pH that are associated with the digestion process. The mineral (in this project we will focus on iron) is housed in small gel micro-beads (approx. 0.1mm diameter). These beads are coated in layers of biopolymers and an impermeable layer of lipid or wax. The biopolymers are commonly used food ingredients such as pectin and proteins, and when assembled in these structures, become sensitive to pH changes. We have shown that they are stable at the acidic pH encountered in the stomach, but can degrade when the pass into the higher pH associated with the small intestine. The impermeable lipid layer will be degraded by enzymes in the duodenum, thus enabling the release of the iron from the micro-bead, and thus be available for absorption. The project has been divided up into tasks that will address the following main objectives. 1. Create and characterise the pH and environmental sensitivity of the biopolymer layers. Using techniques that can measure the mass and composition of these molecular layers, we can determine how the layers respond to changes in pH and select suitable systems. 2. Assemble micro-beads and coat in selected biopolymer layers. Here we will develop methods that will allow us to encapsulate iron loaded microbeads in the impermeable biopolymer layers. 3. Determine stability, encapsulation efficiency and iron release properties. We will measure how much iron escapes from the microbeads during typical processing and storage conditions, and during simulated digestion to ensure they will release the iron under appropriate conditions. We will also use cell culture studies to see if the iron that is released is in a form that can be absorbed by cells lining the small intestine. 4. Determine rates of iron uptake from the coated microbeads. Foods loaded with the micro-beads will be fed to human volunteers and their plasma iron concentrations will be monitored. This will reveal exactly how effective these structures are for enhancing the delivery of iron. If successful the results of this project could be applied to other minerals and water soluble nutrients where fortification is a problem. These approaches could be used in a wide range of foods thus helping to increase the intake of these vital dietary components.