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岁以下儿童患有慢性营养不良。特别是在出生后的头1000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，从而阻碍儿童在成年后充分发挥其潜力和生产力。营养不良的潜在原因是多方面的，但主要有两个因素：1)营养食物摄入不足，含有蛋白质、必需脂肪酸、维生素和矿物质；2)卫生条件差和食品卫生习惯差，导致反复肠道感染或肠道亚临床炎症状态，称为环境肠功能障碍。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，然而，仅针对营养的干预措施已被证明对发育迟缓只有很小的影响。相比之下，食品微生物污染虽然在低收入环境中非常普遍，但受到的关注相对较少。不卫生地制备和喂养受污染的食品常常使儿童面临摄入致病菌和发生肠道感染、腹泻、微生物群失调和环境肠道功能障碍的风险。因此，努力的重点不仅应放在确保有营养不良风险的幼儿获得足够数量的营养食品上，而且应放在确保这些食品的制备卫生上，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联合干预对孟加拉国农村幼儿环境肠功能障碍发展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究竟是如何实现的。因此，我们将研究从干预到环境肠功能障碍发展和生长结局的变化路径上的因素，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及其相互作用。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方法和政策，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.