Malnutrition is a global health issue concerning children and pregnant women in low- and middle-income countries (LMICs). The aim of this review was to assess the health-impact outcomes of interventions addressing food security, water quality and hygiene in order to address the improvement of the nutritional status in children below five years and pregnant women in LMICs. Using PRISMA procedures, a systematic review was conducted by searching in biomedical databases clinical trials and interventions for children and pregnant women. Full articles were screened (nf = 252) and critically appraised. The review included 27 randomized and non-randomized trials and interventions. Based on the analysis, three agents concerning nutritional status were identified. First, exclusive breastfeeding and complementary feeding were fundamental elements in preventing malnutrition. Second, provision of sanitation facilities and the promotion of hygienic practices were also essential to prevent infections spread and the consequent deterioration of nutritional status. Finally, seasonality was also seen to be a relevant factor to consider while planning and implementing interventions in the populations under study. In spite of the efforts conducted over last decades, the improvement in food insecurity rates has remained insufficient. Therefore, the development of global health programs is fundamental to guide future actions.