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

全世界估计有1.55亿5岁以下儿童长期营养不良。 特别是在生命的头1 000天，营养不良会造成有害的发育后果，如身体发育迟缓（“发育迟缓”）、免疫功能受损和认知发育受损，从而使儿童在成年后无法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，但两个主要的促成因素是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，以及2）不良的卫生和食品卫生习惯，导致反复的肠道感染或肠道的亚临床炎症状况，称为环境肠道功能障碍。解决营养不良问题的大多数干预措施都是针对营养摄入途径，但事实表明，仅针对营养的干预措施对发育迟缓的影响很小。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，但却很少受到关注。不卫生地准备和喂养受污染的食物往往使儿童面临摄入致病菌的风险，并发生肠道感染、腹泻、微生物群失调和环境肠道功能障碍。因此，努力的重点不仅应是确保有营养不良风险的幼儿获得足够数量的营养食品，而且还应确保这种食品的制备符合卫生标准，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幼儿环境肠道功能障碍的影响及其对儿童生长发育的后续影响。除了评估干预是否有任何效果外，我们还将调查这些效果是如何实现的。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的变化途径中的沿着因素，包括辅食的微生物污染、肠道病原体负荷、腹泻发作和肠道微生物群组成，以及它们之间的相互作用。该项目的研究结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.