The effect of microbial exposure and environmental enteric dysfunction on child growth – evaluation of a combined nutrition and food hygiene intervention in Bangladesh

在世界范围内，估计有1.55亿5岁以下儿童长期营养不良。特别是在生命的头1000天，营养不良可能导致有害的发育后果，如身体发育迟缓(“发育迟缓”)、免疫功能受损和认知发展受损，从而阻碍儿童在成年后充分发挥其潜力和生产力。营养不良的根本原因是多方面的，但两个主要原因是1)含有蛋白质、必需脂肪酸、维生素和矿物质的营养食物摄入不足，2)卫生和食品卫生做法差，导致反复肠道感染或肠道亚临床炎症状态，称为环境性肠道功能障碍。大多数解决营养不良问题的干预措施都是针对营养摄入的途径，但仅有针对营养的干预措施被证明对发育迟缓只有很小的影响。相比之下，食品的微生物污染虽然在低收入环境中非常普遍，但相对较少受到关注。不卫生的准备和喂养受污染的食物经常使儿童面临摄入病原菌的风险，并患上肠道感染、腹泻、微生物区系失调和环境肠道功能障碍。因此，努力不仅应侧重于确保有营养不良风险的幼儿获得足够量的营养食品，而且还应确保这些食品是以卫生的方式制作的，以防止微生物污染。在拟议的研究中，我们希望评估营养和食品卫生综合干预对孟加拉国农村地区幼儿环境肠道功能障碍发展的影响，以及随后对儿童生长发育的影响。除了评估干预是否有任何效果外，我们还将调查这些具体是如何实现的。因此，我们将研究从干预到环境肠道功能障碍发展和生长结果变化的过程中的因素，包括补充食物的微生物污染、肠道病原体负荷、腹泻发作和肠道微生物区系组成，以及它们之间的相互作用。该项目的成果将有助于制定可持续的营养和卫生综合干预办法和政策，以减少孟加拉国和其他低收入国家儿童的环境肠道功能障碍和营养不良。

Worldwide, an estimated 155 million children under 5 years suffer from chronic undernutrition. Particularly during the first 1000 days of life, undernutrition can cause detrimental developmental consequences, like stunted physical growth (“stunting”), compromised immune function and impaired cognitive development, thereby preventing the children from reaching their full potential and productivity in adulthood. Underlying causes of undernutrition are manifold, but two main contributing factors are 1) insufficient intake of nutritious food, containing protein, essential fatty acids, vitamins and minerals, and 2) poor sanitation and food hygiene practices, leading to repeated enteric infections or a subclinical inflammatory condition of the gut, termed environmental enteric dysfunction. Most interventions addressing the problem of undernutrition are tackling the pathway of nutrient intake, yet nutrition-specific interventions alone have been shown to have only a small effect on stunting. In contrast, microbial contamination of food, although highly prevalent in low-income settings, has received comparatively little attention. Unhygienic preparation and feeding of contaminated food frequently puts children at risk of ingesting pathogenic bacteria and to develop intestinal infections, diarrhea, microbiota dysbiosis and environmental enteric dysfunction. Therefore, efforts should focus not only on ensuring that young children at risk of undernutrition receive a sufficient amount of nutritious food but also on ensuring this food is prepared hygienically in order to prevent microbial contamination. In the proposed study we want to evaluate the effect of a combined nutrition and food hygiene intervention on development of environmental enteric dysfunction in young children in rural Bangladesh and its subsequent impact on child growth and development. In addition to assessing whether the intervention has any effects, we will also investigate how exactly these are achieved. Therefore, we will study factors along the pathway of change from intervention to environmental enteric dysfunction development and growth outcome, including microbial contamination of complementary food, intestinal pathogen load, diarrheal episodes, and intestinal microbiota composition, as well as their interplay. The project findings will contribute to the development of sustainable combined nutrition and hygiene intervention approaches and policies to reduce environmental enteric dysfunction and undernutrition in children in Bangladesh and other low-income countries.