In the United Kingdom, as many as 60% of institutionalized people who are not taking vitamin D supplements may be deficient. Both impaired mineralization and a hyperparathyroidism-related increase in bone turnover have been identified in the presence of vitamin D deficiency. Recent interventional data have confirmed the role of vitamin D deficiency in the pathogenesis of senile osteoporosis and indicated the need to maintain serum cholecalciferol levels within the normal range in elderly people.