• Weight gain during the 12-month follow-up (in grams)
  

• Length gain during the study period (cm)
  
• Cognitive and motor developmental score at the end of trial
  
• Change in blood haemoglobin concentration during the study period (g/l)
  
• Change in serum ferritin concentration during the study period (µg/l)
  
• Mean change in anthropometric indices (weight-for-age z-score [WAZ], weight-for-height z-score [WHZ] and height-for-age z-score [HAZ])
  
• Incidence of undernutrition, stunting and wasting (WAZ, WHZ or HAZ < -2.0)
  

Childhood undernutrition is very common in rural Malawi, like in many other countries in Sub-Saharan Africa. Usually, undernutrition develops between 6 and 24 months of age. By two years of age, 30-50% of all children in rural Malawi are undernourished, predisposing them to subsequent morbidity, developmental delay and mortality. Urgent interventions are needed but the magnitude of the problem precludes a hospital-based management strategy. Therefore, emphasis must be on prevention and early home-based rehabilitation of children with mild-to-moderate malnutrition. However, the options for community based approaches are not as developed as those for institutional management of undernutrition.

The present study tests a recently developed nutrient -dense spread, ready-to use- therapeutic food (RUTF), which offers a potential solution to home based nutrition rehabilitation. The concept has previously been shown to work not only in therapeutic feeding of undernourished children in nutrition rehabilitation units in Malawi but also home based supplementation of undernourished children in Mangochi District, southern Malawi. In the present study the investigators will test the efficacy in growth promotion and other health benefits of this product when provided as a complementary food to infants between 6 and 18 months of age.

The study will be conducted in Lungwena area, Mangochi District, rural Malawi. A total of 180 6-month old infants will be enrolled and randomised to three groups receiving different daily food supplements for 12 months. Children in group-one (control group) will receive 75g of maize/soy flour daily. Children in group-two will receive 25g RUTF daily and children in group-three will receive 50g RUTF daily for a period of 12 months. The food supplements will be delivered to the participant's home at weekly intervals.

All children will undergo medical and anthropometric examinations at 4-monthly intervals and disease symptoms monitoring every week. Dietary intake assessments will be conducted at 12 and 15 months of age. A random sample of 36 children will undergo breast milk intake assessments before the start of food supplementation and during food supplementation. A blood sample will be collected at the beginning and end of the study to measure blood haemoglobin and serum ferritin concentrations and test human immunodeficiency virus [HIV] (at 6 and 18 months).

The impact of the dietary interventions will be primarily assessed by comparing weight gain in the three intervention groups. Secondary outcomes include length gain, incidence of moderate underweight, stunting and wasting, cognitive and motor development at the end of trial and changes in blood haemoglobin and serum ferritin concentration. The study will also produce descriptive data on morbidity and intake of breast milk and other foods during the intervention.