The purpose of this study is to assess the effect of a mixture of prebiotics included in a food supplement on microbiota diversity and functionality, and to explore its subsequent effects on linear growth velocity and morbidity.

The central role of gut microbiota in immunity and nutritional homeostasis is now acknowledged, albeit not fully understood. Gut microbiota composition imbalances have been found in malnourished children, which were not restored by nutritional interventions as currently conducted. Therefore, the necessity to design more complete nutritional interventions that include gut health has been advised by expert committees.

Prebiotics are compound that selectively enhance the growth of beneficial gut bacteria. They have been recommended and used in infant formula and weaning cereals resulting in gut microbiota resembling that of breastfed infants in formula fed infants in developed countries. A healthy gut microbiota was shown to be associated with enhanced growth patterns and decreased morbidity in children in developed countries. Evidence of such outcome is lacking in developing countries, yet such results would be particularly valuable for children from these settings, living in rather poor sanitary conditions in an environment characterized with high infectious disease load, conditions that mostly explain the high prevalence of chronic malnutrition. This study aims to assess the effect of a 6 months' supplementation with a lipid based nutrient supplement fortified with fructo-oligosaccharides and inulin on microbiota diversity and functionality in rural Burkinabe infants, and to explore its subsequent effects on linear growth velocity and morbidity.

Inclusion Criteria:

• 6-6.5 month old infants
• Weight for height and height for age z-score above -2
• Permanent resident of the area and not intending to move for the next 6 months for more than a week
• No chronic antibiotic treatment
• Exempt of any current serious illness
• Still breastfed.

Exclusion Criteria:

• Moderate or severe malnutrition (weight for height or height for age z-score below -2)
• non-permanent residence in the study area,
• the presence of any congenital anomalies in the child or mental/physical disease of the mother that can interfere with child feeding
• a chronic antibiotic treatment i.e. more than 6 weeks treatment at the time of enrolment
• a history of allergy to a constituent of the supplement
• a serious current illness

Upon publication of the main findings, data will be shared on a public repository and made publicly available on request as per recently published guidance and regulations (BMJ 2016;352:i255)