|
Vitamin A is one of the most versatile vitamins, with roles in such diverse functions as vision, immune defenses, maintenance of body linings and skin, bone and body growth, normal cell development, and reproduction.
Vitamin A helps form and maintains healthy teeth, skeletal and soft tissue, mucous membranes, and skin. Thus vitamin A and related nutrients may collectively be important in protecting against conditions related to oxidative stress, such as aging, air pollution, arthritis, cancer, cardiovascular disease, cataracts, diabetes mellitus and infection.
Vitamin A is essential to normal growth. Vitamin A is necessary for cell growth and cell differentiation - the process by which a cell changes its structure and develops specific functions.
It plays important roles in resproduction, bone growth and tooth development. The primary functions of vitamin D are stimulation of calcium and magnesium absorption, two minerals that are essential for strong bones.
Vitamin D3 is necessary for the ultilization of calcium and phosphorus, and for the assimilation of vitamin A.
Cholecalciferol increases the serum calcium concentrations by increasing GI absorption of phosphorus and calcium, increasing osteoclastic resorption, and increasing distal renal tubular reabsorption of calcium.
Proper levels are necessary to maintain bone mineral density and serum (blood) calcium levels. This is especially true among the very young where it is used to treat rickets and in combination with vitamin A for the treatment of osteoporosis in the elderly, particularly post menopausal women who are often subject to fractures due to loss of bone density.
|