Vitamin E. Vitamin D, or cholecalciferol, functions as both a vitamin and a hormone. It is required for the absorption and utilization of calcium and helps calcium to be deposited in your bones. Even marginal or slight deficiencies of vitamin D can increase your risk of osteoporosis and deterioration of the joints.itamin D, or cholecalciferol, functions as both a vitamin and a hormone. It is required for the absorption and utilization of calcium and helps calcium to be deposited in your bones. Even marginal or slight deficiencies of vitamin D can increase your risk of osteoporosis and deterioration of the joints.