During the last decades of colonial rule, Belgian colonial authorities, health agencies and researchers intensely engaged with kwashiorkor, a severe syndrome that was deemed widespread among young children in some parts of the Belgian Congo and Ruanda-Urundi and chiefly attributed to protein malnutrition. To fight kwashiorkor, the Belgian government, in the early 1950s, set up a joint milk distribution campaign with the United Nations International Children’s Emergency Fund, Food and Agriculture Organization and World Health Organization, the first of its kind in colonial Africa. Placing this campaign in the context of mounting international and inter-imperial concern about kwashiorkor and other nutritional problems in Africa and across the globe, this article explores its rationales, mechanisms and consequences, and in particular, how the campaign was shaped and publicised by FORÉAMI, one of the main health providers on the ground. It not only contributes to the history of European colonial medicine and nutritional policies, but also opens new perspectives on international health collaboration during late colonialism. It argues that Belgian authorities were wary of international interference in colonial policies, but that especially FORÉAMI also viewed and used the campaign as an opportunity to display its ‘mastery’ in rural and infant healthcare and control the narrative on Belgium’s colonial medicine.