Child Health, Agriculture and Integrated Nutrition (CHAIN): a Randomized Trial to Close the Nutrient Gap in Rural Zimbabwe

Linear growth failure (stunting) in childhood is the most prevalent form of undernutrition globally. Diets in rural sub-Saharan Africa have low dietary diversity and a reliance on white maize, which is high in starch and low in other nutrients. Improving infant and young child feeding (IYCF) during the period of complementary feeding from 6-24 months of age, including use of daily small-quantity lipid-based nutrient supplements (SQ-LNS), has a modest impact on linear growth. However, despite intensive IYCF interventions, infants often still have nutrient gaps. Furthermore, three key biological barriers (environmental enteric dysfunction, dysbiosis of the gut microbiota, and systemic inflammation) limit nutrient uptake and utilisation.

The overarching goal of this trial is to fill key nutrient gaps among infants in rural sub-Saharan Africa through an improved IYCF intervention using locally available foods that can ultimately be self-sustaining through agriculture. Addressing intake, uptake and utilization of nutrients in tandem, through use of 'functional foods' could ultimately improve growth and development in young children.

CHAIN is an open-label, individually randomized trial of improved infant and young child feeding (IYCF) versus "IYCF-plus" among 192 infants enrolled between 5-6 months of age in Shurugwi district, rural Zimbabwe. Interventions comprise sequential behaviour-change interventions delivered by village health workers together with food supplements. In the IYCF arm, infants will receive white maize and small-quantity lipid-based nutrient supplement (SQ-LNS) daily from 6 months of age. In the IYCF-plus arm, infants will receive orange pro-vitamin A-biofortified maize, and daily SQ-LNS, plus additional foods that are nutrient-rich, culturally acceptable and locally sustainable: NUA-45 biofortified sugar beans, moringa leaf powder and whole egg powder. For the duration of the trial, these foods will be provided as dried powders, which can be added to infant porridge as point-of-use fortificants. Together, these food supplements have the added plausible benefit of improving the microbiota and gut barrier function and reducing intestinal and systemic inflammation.

The primary outcome will be the proportion of infants in each trial arm reaching daily energy requirements at 9 months of age (visit window 9-11 months of age). Secondary outcomes are intake of protein, iron, zinc and folate; height-for-age Z score, weight-for-age Z-score, and weight-for-height Z-score; and haemoglobin. Tertiary outcomes are laboratory measures of microbiome composition, environmental enteric dysfunction, inflammation, innate immune function, circulating choline and essential amino acids, and urinary metabolic profile. Two qualitative substudies will explore i) the feasibility and acceptability of the IYCF-plus intervention; and ii) the influence of migration on household food consumption and production.

Trained research nurses will collect baseline data on maternal and infant demographics, nutritional status and household characteristics. Infants will have anthropometry measurements undertaken, and baseline infant stool, urine and blood samples will be collected by the research nurse.