There is increasing recognition that nutrition strongly influences the risk of age-related chronic diseases and mortality. In older adults, inadequate calcium intake and vitamin D deficiency contribute to sarcopenia and osteoporosis. While calcium supplementation alone offers limited fracture protection, vitamin D combined with calcium significantly reduces hip and fragility fractures, particularly in individuals over 70 and those institutionalized, and may also improve muscle function and reduce falls. Beyond skeletal health, low vitamin D levels have been linked to higher risks of dementia, diabetes, cancer, and infections, although further high-quality studies are needed to clarify its broader preventive and therapeutic roles in older persons.