The Role of Plant Cell Walls in Regulating Starch and Lipid Bioaccessibility from Plant Foods: In Silico In Vitro and In Vivo Studies

大多数人通常吃富含淀粉的植物性食物，特别是谷物产品（如面包，米饭），以及一些富含脂肪的食物（如树坚果）。然而，人们对这些食物如何在人体肠道中释放淀粉和脂肪以及这反过来如何影响消化并最终影响营养物质的吸收知之甚少。提高我们对这些过程的理解对于研究食物在肠道中的行为及其对新陈代谢的影响的基础科学家来说非常重要。对于担心过度食物消费和日益严重的肥胖问题以及相关的心脏病和糖尿病问题的卫生专业人员和政策制定者来说，这也很重要。此外，淀粉和脂肪消化和吸收到血液中的速度和程度是改变心脏病风险的重要因素。从植物性食物中释放脂肪和淀粉以及身体对这些营养素的消化和吸收是非常复杂的过程。我们在理解这些过程方面的进展受到植物性食物和单个营养素的极其复杂的结构和性质的阻碍。我们的项目提案汇集了来自不同机构和学科的世界专家的独特组合。这些专家组成了一个庞大的团队，以提高我们对可食用植物在肠道中的行为以及肠道如何对可供消化的淀粉和脂肪作出反应的知识。例如，了解植物性食物在肠道中沿着移动时释放营养物质的速率是很重要的，因为这会影响消化和吸收的时间进程。这反过来又会影响营养物质在体内代谢的方式。我们目前正在研究杏仁和谷物，例如小麦，以了解脂肪和淀粉如何从植物组织中释放出来。淀粉，脂肪和其他营养物质存在于构成植物组织的许多细胞中，例如杏仁种子含有约5000万个细胞。这些细胞的尺寸非常小，通常直径小于约十分之一毫米。似乎影响植物细胞释放营养素的一个重要因素是细胞壁的存在，在营养学中更常被称为“膳食纤维”。淀粉和脂肪是如何从这些细胞中释放出来的，人们对此知之甚少。初步研究将涉及检查细胞壁作为物理屏障在控制营养物质释放和消化中的作用，使用各种方法在细胞尺度上检查植物组织。一种新的方法是使用最近建立的“动态胃模型”，这是一种计算机控制的人体胃消化模拟。我们还将用富含脂肪和淀粉的相同植物性食物喂养人类志愿者，以确定加工和咀嚼对营养释放和消化的影响，以及消化的营养物质输送到血液中的速度。最后，我们还将对脂肪和淀粉如何在消化过程中从可食用植物组织中释放出来进行数学描述。据设想，在未来，数学的使用将使研究科学家能够预测类似食物在肠道中的行为，而无需进行如此多的实验室实验。这项工作将有助于食品工业生产新的食品或成分，这些食品或成分在肠道中控制淀粉和脂肪的释放，例如，这可能有助于降低心脏病的风险。事实上，大型食品制造商Premier Foods已同意与我们合作，并提供科学和技术专业知识。Premier Foods还同意提供谷物（如小麦）和用这些谷物制成的食品，所有这些产品都经过特别准备，以控制淀粉释放。这些原材料和食品将用于我们的项目，以研究它们在肠道中的行为，并评估它们在降低心脏病风险方面的潜在益处。

Most people commonly eat plant foods rich in starch, notably cereal products (e.g. bread, rice), and also some that are rich in fat (e.g. tree nuts). However, little is known about how such foods release starch and fat in the human gut and how, in turn, this may influence digestion and ultimately the absorption of nutrients into the body. Improving our understanding of these processes is important for basic scientists studying the behaviour of foods in the gut and their effects on metabolism. It is also important for health professionals and policy makers that are worried about excessive food consumption and the growing problem of obesity and associated problems of heart disease and diabetes. Moreover, the rate and extent of starch and fat digestion and absorption into the blood stream are important factors in altering the risk of heart disease. The release of fat and starch from plant foods and the digestion and absorption of these nutrients by the body are highly complex processes. Our progress in understanding these processes is impeded by the hugely complex structure and properties of plant foods and individual nutrients. Our project proposal brings together a unique combination of world experts from different institutions and disciplines. These experts have formed a large team in order to improve our knowledge of how edible plants behave in the gut and how the gut reacts to the starch and fat available for digestion. For example, it is important to know about the rate at which nutrients are released from plant foods as they move along the gut, since this will affect the time course of digestion and absorption. This in turn will influence the way the nutrients are metabolised within the body. We currently study almond nuts and cereals, e.g. wheat, to see how fat and starch are released from plant tissues. Starch, fat and other nutrients are found inside numerous cells that make up the plant tissue, e.g. an almond seed contains about 50 million cells. Such cells are very small in size, often with a diameter of less than about one tenth of a mm. One significant factor that seems to affect nutrient release from plant cells is the presence of cell walls, more commonly referred to in nutrition as 'dietary fibre'. How starch and fat are released from these cells is poorly understood. Initial studies will involve examining the role of cell walls as physical barriers in controlling the release and digestion of nutrients, using various methods to examine plant tissue at a cellular scale. One novel method will be the use of a recently established 'Dynamic Gastric Model', a computer-controlled simulation of digestion in the human stomach. We will also feed human volunteers with the same plant foods rich in fat and starch, to determine the effects of processing and mastication on nutrient release and digestion and the rate at which digested nutrients are transported into the blood stream. Finally, we will also produce a mathematical description of how fat and starch are released from edible plant tissues during digestion. It is envisaged that in the future, the use of mathematics will allow research scientists to predict the behaviour of similar foods in the gut without having to do so many laboratory experiments. This work will help the food industry to produce new food products or ingredients that have a controlled release of starch and fat in the gut, which could, for example, help to reduce the risk of heart disease. Indeed, Premier Foods, a large food manufacturer, has agreed to collaborate with us and provide scientific and technological expertise. Premier Foods has also agreed to provide cereals (e.g. wheat) and food products made with these cereals, all of which have been specially prepared to control starch release. These raw materials and food products will be used in our project to study how they behave in the gut and assess their potential benefits in reducing the risk of heart disease.