Different age groups have varying nutritional needs based on factors such as growth, development, and metabolic rate. For instance, children require higher levels of certain nutrients, like calcium and iron, to support bone growth and cognitive development. Adults generally focus on maintaining health and preventing chronic diseases, often needing adequate fiber, vitamins, and minerals. Additionally, seniors may focus on preserving muscle mass and maintaining bone density, often requiring more protein and certain vitamins like D and B12. Overall, nutritional needs evolve throughout life stages.