Nutritional deficiency is a condition in which the body has an insufficient supply or availability of one or more essential nutrients to support normal physiological functions, growth, development, and maintenance of health. It may involve macronutrients, such as proteins and essential fatty acids, or micronutrients, including vitamins and minerals. Nutritional deficiencies can result from inadequate dietary intake, impaired digestion or absorption, increased physiological requirements, excessive nutrient losses, or disturbances in nutrient metabolism and utilization ^[1][2]. Their severity ranges from subclinical depletion, which may be difficult to detect, to clinically apparent conditions associated with characteristic signs, symptoms, or impaired physiological function ^[2]. Assessment may involve dietary evaluation, clinical examination, and biochemical or other validated biomarkers, depending on the nutrient and clinical context ^[1]. Nutritional deficiency is distinct from general malnutrition, which also encompasses excessive nutrient intake, imbalances in nutrient consumption, and impaired nutrient utilization ^[3].