The World Health Organization (WHO) defines malnutrition as “the cellular imbalance between the supply of nutrients and energy and the body's demand for them to ensure growth, maintenance and specific functions". This imbalance includes both inadequate and excessive energy intake; the former leads to malnutrition in the form of wasting, stunting and underweight, while the latter leads to overweight and obesity. Macronutrient and micronutrient deficiencies negatively impact growth, body composition, muscle strength, intelligence, body development and quality of life in childhood. age range. In children, undernutrition manifests as underweight and stunting (short stature), while severely undernourished children exhibit the symptoms and signs that characterize conditions known as kwashiorkor, marasmus, or marasmic-kwashiorkor. Malnutrition generally involves undernutrition and refers to all deviations from adequate and optimal nutritional status in infants, children, and adults. Deficiencies of macronutrients such as proteins, carbohydrates and fats result in protein-calorie malnutrition (PCM) and, when combined with micronutrient deficiencies, are among the most important nutritional problems with hundreds of millions of pregnant women, the elderly and young children particularly affected. Malnutrition is one of the most important causes of infant mortality in developing countries, particularly during the first 5 years of life (Pelletier, DL, 1995), the main causes of which are poverty, world conflicts, lack of education , natural disasters and poor access to healthcare. PCM usually occurs early in children between 6 months and 2 years of age and is associated with early weaning, delayed...... mid-paper ......0.41. Malnutrition has lifelong implications because it severely reduces children's ability to learn and grow to their full potential and leads to less productive adults, poor performance, and wasted government resources. Some research and studies have shown that the relationship between infection and malnutrition is bidirectional 36,37. A variety of mechanisms cause a weakened immune system due to malnutrition, leading to increased susceptibility to infections. On the other hand, the infection causes the loss of important micro and macro nutrients which lead to alterations in nutritional levels. Malnourished children contract gastrointestinal and respiratory bacterial infections more frequently. 42. Malnutrition significantly compromises mucosal epithelial barriers in the gastrointestinal, respiratory and urogenital tracts which represent the first line of defense against infections.