The article by Prado and Dewey provides an overview of the impact of early nutrient deficiencies on long-term brain function, cognition, and productivity, focusing on research from low- and middle-income countries. It highlights the importance of adequate nutrition during pregnancy and infancy, which are critical periods for brain development. Animal studies have demonstrated that nutrient deficiencies can impair neurodevelopmental processes such as neuron proliferation and myelination. However, several factors influence whether these deficiencies lead to permanent cognitive deficits in humans, including environmental stimulation, the timing and degree of deficiency, and the possibility of recovery. The article discusses four key factors that influence the impact of undernutrition: 1. **Environmental Stimulation**: The quality and quantity of sensory and social input can affect neurodevelopmental processes. 2. **Timing of Deficiency**: Nutrient deficiencies during critical periods are more likely to impair brain development. 3. **Degree of Deficiency**: Severe to moderate deficiencies are more likely to cause impairments, while mild deficiencies may not. 4. **Possibility of Recovery**: Nutritional supplementation and enhanced environmental stimulation can help correct some of the negative effects of early undernutrition. The article also reviews human studies, particularly in low- and middle-income countries, where multiple nutrient deficiencies are prevalent. It examines the long-term consequences of undernutrition, the effectiveness of food and protein/energy supplementation, breastfeeding practices, essential fatty acids, and specific micronutrients. While some interventions have shown positive effects, the timing and degree of deficiency remain critical factors. The article emphasizes the need for further research to better understand the mechanisms and optimal timing of interventions to promote healthy brain development.The article by Prado and Dewey provides an overview of the impact of early nutrient deficiencies on long-term brain function, cognition, and productivity, focusing on research from low- and middle-income countries. It highlights the importance of adequate nutrition during pregnancy and infancy, which are critical periods for brain development. Animal studies have demonstrated that nutrient deficiencies can impair neurodevelopmental processes such as neuron proliferation and myelination. However, several factors influence whether these deficiencies lead to permanent cognitive deficits in humans, including environmental stimulation, the timing and degree of deficiency, and the possibility of recovery. The article discusses four key factors that influence the impact of undernutrition: 1. **Environmental Stimulation**: The quality and quantity of sensory and social input can affect neurodevelopmental processes. 2. **Timing of Deficiency**: Nutrient deficiencies during critical periods are more likely to impair brain development. 3. **Degree of Deficiency**: Severe to moderate deficiencies are more likely to cause impairments, while mild deficiencies may not. 4. **Possibility of Recovery**: Nutritional supplementation and enhanced environmental stimulation can help correct some of the negative effects of early undernutrition. The article also reviews human studies, particularly in low- and middle-income countries, where multiple nutrient deficiencies are prevalent. It examines the long-term consequences of undernutrition, the effectiveness of food and protein/energy supplementation, breastfeeding practices, essential fatty acids, and specific micronutrients. While some interventions have shown positive effects, the timing and degree of deficiency remain critical factors. The article emphasizes the need for further research to better understand the mechanisms and optimal timing of interventions to promote healthy brain development.