Efficacy of a multi-micronutrient dietary intervention based on haemoglobin, hair zinc concentrations, and selected functional outcomes in rural Malawian children

OBJECTIVE: To investigate the efficacy of enhancing the content and bioavailability of micronutrients in diets of stunted rural Malawian children on their growth and body composition, morbidity, anaemia and hair zinc concentrations. DESIGN: A quasi-experimental design with non-equivalent control group involving 410 intervention and 220 control children aged 30-90 months. SETTING AND SUBJECTS: Children from two intervention and two control villages in Mangochi District, Southern Malawi participated in a 6 month dietary intervention. Anthropometry, malarial screening, haemoglobin, and hair zinc were measured at baseline and after 12 months, as well as socio-economic status at baseline, and common infections monthly post-intervention. RESULTS: Groups were comparable at baseline. Post-intervention children had greater Z-scores for lean body mass (mid-upper arm circumference -0.75 vs -1.05; arm muscle area: 0.63 vs -1.03, P<0.001) than controls but Z-scores for weight-for-height and height-for-age were similar. After controlling for baseline variables, mean haemoglobin was higher (107 vs 102 g/l, P<0.01), whereas the incidence of both anaemia (62 vs 80%) and common infections (based on a median overall illness score for fever, diarrhoea, upper and lower respiratory infections) were lower in intervention compared to controls, with no change in hair zinc concentrations or malaria status post-intervention. CONCLUSION: Improvements in the micronutrient adequacy of diets of post-intervention children were associated with a favourable increase in indices of lean body mass and reductions in the incidence of anaemia and common infections in these rural Malawian stunted children.