Human Development and Health Academic Unit, Faculty of Medicine, University of Southampton, Tremona Road, Southampton SO16 6YD, UK.
Proc Nutr Soc. 2013 Aug;72(3):299-309. doi: 10.1017/S0029665113001286. Epub 2013 May 21.
A well-functioning immune system is key to providing good defence against pathogenic organisms and to providing tolerance to non-threatening organisms, to food components and to self. The immune system works by providing an exclusion barrier, by identifying and eliminating pathogens and by identifying and tolerating non-threatening sources of antigens, and by maintaining a memory of immunological encounters. The immune system is complex involving many different cell types distributed throughout the body and many different chemical mediators some of which are involved directly in defence while others have a regulatory role. Babies are born with an immature immune system that fully develops in the first few years of life. Immune competence can decline with ageing. The sub-optimal immune competence that occurs early and late in life increases susceptibility to infection. Undernutrition decreases immune defences, making an individual more susceptible to infection. However, the immune response to an infection can itself impair nutritional status and alter body composition. Practically all forms of immunity are affected by protein-energy malnutrition, but non-specific defences and cell-mediated immunity are most severely affected. Micronutrient deficiencies impair immune function. Here, vitamins A, D and E, and Zn, Fe and Se are discussed. The gut-associated lymphoid tissue is especially important in health and well-being because of its close proximity to a large and diverse population of organisms in the gastrointestinal tract and its exposure to food constituents. Certain probiotic bacteria which modify the gut microbiota enhance immune function in laboratory animals and may do so in human subjects.
一个运作良好的免疫系统是提供对病原体良好防御的关键，也是对非威胁性生物体、食物成分和自身提供耐受性的关键。免疫系统通过提供排斥屏障、识别和消除病原体以及识别和耐受非威胁性抗原来源，并通过保持对免疫接触的记忆来发挥作用。免疫系统很复杂，涉及到分布在全身的许多不同的细胞类型和许多不同的化学介质，其中一些直接参与防御，而另一些则具有调节作用。婴儿出生时免疫系统不成熟，在生命的头几年完全发育。免疫能力会随着年龄的增长而下降。生命早期和晚期出现的免疫能力不足会增加感染的易感性。营养不良会降低免疫防御能力，使个体更容易感染。然而，感染的免疫反应本身也会损害营养状况并改变身体成分。几乎所有形式的免疫都受到蛋白质-能量营养不良的影响，但非特异性防御和细胞介导的免疫受到的影响最严重。微量营养素缺乏会损害免疫功能。在这里，讨论了维生素 A、D 和 E 以及 Zn、Fe 和 Se。肠道相关淋巴组织因其与胃肠道中大量和多样化的生物体的密切接近及其对食物成分的暴露而在健康和福祉中尤为重要。某些益生菌可以改变肠道微生物群，增强实验动物的免疫功能，在人类受试者中也可能如此。
