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.