Recommended Dietary Allowances (RDAs) are scientifically established nutrient intake levels designed to meet the nutritional needs of nearly all healthy individuals in a specific age, sex, and physiological group. They serve as an essential guide for planning balanced diets, promoting health, preventing nutrient deficiencies, and reducing the risk of diet-related diseases. In community nutrition, RDAs provide a practical framework for assessing dietary adequacy, formulating nutrition policies, designing feeding programmes, and educating individuals and communities about healthy eating practices. They represent the average daily dietary intake level sufficient to meet the nutrient requirements of approximately 97–98 percent of healthy individuals in a defined population group. The concept of Recommended Dietary Allowances emerged from the recognition that human beings require specific amounts of nutrients for normal growth, development, maintenance of body functions, reproduction, and physical activity. Since nutrient needs vary according to age, sex, body size, activity level, physiological conditions such as pregnancy and lactation, and environmental factors, a single dietary recommendation cannot be applied universally. Therefore, RDAs are developed separately for different population groups, ensuring that recommendations are both scientifically valid and practically useful. The primary objective of RDAs is to ensure optimal nutritional status rather than merely preventing deficiency diseases. Earlier nutritional recommendations focused mainly on preventing conditions such as scurvy, rickets, pellagra, beriberi, and night blindness. Modern RDAs, however, aim to support overall health, maximize growth and development, strengthen immunity, enhance cognitive performance, improve physical efficiency, and reduce the long-term risk of chronic diseases such as obesity, diabetes, cardiovascular diseases, hypertension, and osteoporosis. The formulation of RDAs is based on extensive scientific research involving clinical studies, metabolic experiments, epidemiological investigations, dietary surveys, and nutrient balance studies. Scientists determine the average nutrient requirement of a population group and then add a safety margin to account for biological variability among individuals. This safety margin ensures that almost all healthy individuals in that group receive sufficient nutrients when consuming diets meeting the RDA. Several factors influence the determination of Recommended Dietary Allowances. Age is one of the most significant determinants because nutrient needs change throughout the life cycle. Infants require nutrients that support rapid growth and brain development. Children need adequate protein, calcium, phosphorus, iron, and vitamins for physical growth and cognitive development. Adolescents require increased energy and nutrients due to rapid growth spurts and hormonal changes. Adults need nutrients to maintain body tissues and physiological functions, while older adults may require adjustments in nutrient intake because of changes in metabolism, digestion, and nutrient absorption. Sex also influences nutrient requirements. Men generally require higher energy intake because of greater lean body mass and higher basal metabolic rate. Women have increased requirements for iron during reproductive years because of menstrual blood loss. Pregnancy and lactation significantly increase the need for energy, protein, calcium, iron, folic acid, iodine, zinc, and several vitamins to support fetal growth, maternal tissue expansion, milk production, and infant development. Physical activity is another important determinant of RDAs. Individuals engaged in sedentary occupations require less energy than those involved in moderate or heavy physical labour. Athletes and manual workers require higher energy, protein, and fluid intake to compensate for increased energy expenditure and tissue repair. Body size and composition also affect nutrient requirements. Larger individuals generally require more energy than smaller individuals. Lean body mass influences metabolic rate and protein requirements. Environmental conditions such as climate may alter energy expenditure and water needs. Cold environments increase energy requirements for maintaining body temperature, whereas hot climates increase fluid and electrolyte requirements because of excessive sweating. Health status influences nutrient needs considerably. During illness, infection, trauma, burns, surgery, and recovery periods, the body's metabolic demands often increase. Although RDAs are intended primarily for healthy individuals, healthcare professionals use modified nutrient recommendations for patients with specific medical conditions. The process of establishing Recommended Dietary Allowances involves determining the Estimated Average Requirement (EAR), which represents the average nutrient intake estimated to meet the needs of half the healthy individuals