Effectiveness of small-quantity versus medium-quantity lipid-based nutrient supplements for prevention of undernutrition in young children: protocol for an individually randomised, parallel-group, non-inferiority trial.

introductionUndernutrition during the first 2 years of life remains a major public health challenge in Pakistan. Lipid-based nutrient supplements (LNS) are widely used to prevent growth faltering in nutritionally at-risk populations. Evidence shows that small-quantity LNS (SQ-LNS, 20 g/day) is effective in preventing undernutrition; however, evidence comparing SQ-LNS with medium-quantity LNS (MQ-LNS, 50 g/day) under programmatic conditions (especially in food-insecure poor households) remains limited. Given that the MQ-LNS daily dose may be too large for older infants to consume fully, comparative effectiveness evidence is needed to inform the national stunting prevention programme. This study compares the effectiveness of SQ-LNS versus MQ-LNS in reducing undernutrition (stunting, wasting and underweight) and anaemia among children aged 6-12 months enrolled in the Benazir Nashonuma Programme (BNP), a government-led nutrition-sensitive social protection programme. METHODS AND ANALYSIS: This will be an individually randomised, parallel-group, non-inferiority trial conducted within BNP facilitation centres in Dadu and Peshawar districts. Eligible children aged 6-7.5 months will be randomised 1:1 to receive either 20 g/day SQ-LNS or 50 g/day MQ-LNS for 6 months. The primary outcome is stunting assessed using the WHO's Child Growth Standards. Secondary outcomes are wasting, underweight, anthropometric z-scores, morbidity and anaemia. The required sample size is estimated at 1060 (530 per arm) for Dadu and 508 (254 per arm) for Peshawar. Analyses will follow a non-inferiority framework using a mixed-effects logistic regression model adjusted for relevant covariates. Additionally, we will assess utilisation and acceptability of the intervention among beneficiaries. ETHICS AND DISSEMINATION: Ethical approval has been obtained from the Aga Khan University Ethical Review Committee (2025-11806-38699) and the National Bioethics Committee of Pakistan (NBCR-1380). We will obtain written informed consent from mothers of eligible children. Findings will be disseminated through engagement with government stakeholders and implementing partners, as well as through peer-reviewed publications and scientific forums. TRIAL REGISTRATION NUMBER: NCT07451951.