Sample Size: 1200 children (400 in each group) Enrollment of eligible children and Base line information: Details of all eligible children will be obtained from the schools to be a part of the study and their parents will be contacted for an appointment either by telephone or sending a note. Consent for participation will be sought after evaluating inclusion and exclusion criteria and will be randomized to receive either fortified or non fortified yoghurt, similarly consent will be obtained from the parents of children from the non yoghurt area who will not be given any intervention. Baseline information on socioeconomic information, retrospective morbidity information of the child for the last 15 days, hospitalization, hygiene and sanitation information will be recorded. Baseline clinical assessments and anthropometric measurements will be conducted. 5 ml of venous blood sample (approx. one spoonful of blood) and mid stream urine sample will be obtained by a trained nurse/technician employed by the project. Developmental assessments measuring children's intelligence and executive functioning (WISC, KCPT, WCST) will be conducted using standardized tests. Blood/urine sampling will not be done for the children in the pure control group (no intervention).