This is a nutritional observational trial with two arms: 1) Intervention arm of Probiotic Yoghurt containing Lactobacillus rhamnosus yoba 2012 and 2) Control arm of milk. About 500 children in each arm will be enrolled. Children will be enrolled in the yoghurt or the milk arm, based on the preference of the school and the parents in response to a sensitization campaign of a non-governmental organization (NGO) in the region. This selection will therefore be non-randomized and non-blinded. Within one school, all children will be enrolled in the same arm. The children will be monitored for 3 weeks in the baseline. Subsequently, the children will consume either 100ml of yoghurt or 100ml of milk, once per day for five days per week for nine weeks, while being continuously monitored. The milk and the yoghurt will be locally sourced in the district where the schools are located.

This is an observational nutritional trial with two arms: 1) Intervention arm of Probiotic Yoghurt containing Lactobacillus rhamnosus yoba 2012 and 2) Control arm of milk. About 500 children in each arm will be enrolled. Children will be enrolled in the yoghurt or the milk arm, based on the preference of the school and the parents in response to a sensitization campaign of an NGO in the region. This selection will therefore be non-randomized and non-blinded. Within one school, all children will be enrolled in the same arm. The children will be monitored for 3 weeks in the baseline. Subsequently, the children will consume either 100ml of yoghurt or 100ml of milk, once per day for five days per week for nine weeks, while being continuously monitored. The milk and the yoghurt will be locally sourced in the district where the schools are located. Monitoring and data collection tools include:

1. Baseline, midline and end line questionnaire administered to parents to identify confounding factors (e.g. use of medication and diet from home) of treatment and control group.
2. Weight, height, mid-upper-arm circumference MUAC and head circumference measurements every 4 weeks for 3 months in both the treatment and control groups (total 4 times). One point measurement will be taken 6 months after the study.
3. Daily monitoring of the incidence of RTIs, diarrhoea, skin rashes or other diseases in treatment and control groups by teachers with confirmation of a nurse in a mobile app.

Children from pre-primary institutions in which both the management and the parents have recently decided to purchase either milk or yoghurt for the pupils on regular basis will be recruited. The study subjects (children) are recruited at these institutions. Only children from parents who have agreed to contribute to the consumption of milk / yoghurt and who have furthermore consented for their children to be measured and monitored for the purpose of the current study will be recruited. The parent is free to provide his/her child with milk / yoghurt, even if the parent does not consent for the child to take part in the study.

The study will start three weeks before either milk or yoghurt consumption commences, in order to establish a solid baseline. With the help of tablets and a specially designed app, nurses will keep track of their pupils' health by tracking incidence of diarrhoea, respiratory tract infections, skin rashes and other diseases. Teachers will keep track of the daily attendance of pupils.

Measurements of weight, height, MUAC and head circumference will be measured by a nurse every four weeks, starting three weeks prior to the start of the consumption of either milk or yoghurt. The measurements will be conducted with the help of Standard Operations Procedures as provided by Life Study and analysed with the help of World Health Organization (WHO) guidelines.

During these 3 months in which the children will be monitored, a questionnaire will be administered to the parents of the children at the start, middle and end of the study. The primary objective and content of the questionnaire is related to diet of the children outside school, in order to determine whether there are significant differences between the diets of the children in the treatment group and in the control group. The questionnaires will furthermore include questions about absenteeism and causes thereof, incidence of diarrhoea, Respiratory Tract Infections or any other diseases, and the use of any type of drug or treatment, in order to verify and supplement the information provided by the class-teacher.

Inclusion Criteria:

• During interactions with the pre-primary institutions prior to the study, the parents of the children have agreed to pay for their child to either take milk or probiotic yoghurt (100ml five times per week).
• Parents are willing to provide written consent for their child to participate in the study, and children are willing to provide assent

Exclusion Criteria:

• The child does not comply with the inclusion criteria
• The child has an aversion against yoghurt or milk
• The child is lactose-intolerant as indicated by the parent, or has any other medical condition that will prevent him/her from taking yoghurt or milk.

Children 3-6 years old attending pre-primary schools in the districts Kiruhura, Lyantonde, Sheema, Bushenyi, Mbarara, Isingiro or Ntungamo in Southwest Uganda. Children of all genders and all health statuses are enrolled.

Data will be uploaded to the online respiratory of the app as developed by Omnitech. This data will only be accessible to the researchers who have been granted the password. Besides, data will be primarily entered in excel, and analysed with the help of Statistical Package for Social Sciences (SPSS). Data will be cross validated by the different researchers involved. Data will be handled confidentially and anonymously, provided with a code and will be only accessible to the researchers.

The data collection app will create monthly health reports, which will be shared with parents to enable them to closely monitor the health and development of their children.