Vitamin D is a prohormone (a broken-open steroids called a secosteroid), that is converted in the liver and kidney to become the hormone 1,25-D (physiologically active form of a protein bound vitamin D). Vitamin D3 (Cholecalciferol) is the natural dietary secosteroid to our body's internal 1,25-Hydroxyvitamin D3.
A major biologic function of Vitamin D is to maintain normal blood levels of calcium and phosphorus. Promotes strong bones and teeth, prevents rickets, works to maintain good health and vitality. Protects against muscle weakness. Helps regulate the heart (through calcium absorption). Aids calcium absorption and helps build bone mass and prevents bone loss.
Vitamin D exists in several forms, each with a different activity. Some forms are mostly inactive in the body, and have limited ability to function as a vitamin. The liver and kidney help convert vitamin D to its active hormone form.
Vitamin D aids in the absorption of calcium, helping to form and maintain strong bones. It promotes bone mineralization in concert with a number of other vitamins, minerals, and hormones. Without vitamin D, bones can become thin, brittle, soft, or misshapen. Vitamin D prevents rickets in children and osteomalacia in adults, which are skeletal diseases that result in defects that weaken bones.
Exposure to sunlight is an important source of vitamin D. Ultraviolet (UV) rays from sunlight trigger vitamin D synthesis in the skin. Season, latitude, time of day, cloud cover, smog, and suncreens affect UV ray exposure. For example, in Chicago from November through February, the average amount of sunlight is insufficient to produce significant vitamin D synthesis in the skin. Sunscreens with a sun protection factor of 8 or greater will block UV rays that produce vitamin D, but it is still important to routinely use sunscreen whenever sun exposure is longer than 10 to 15 minutes. It is estimated that individuals with skin phototype II (fairer-skinned) need five minutes of noontime summer sun exposure two-to-three times per week to satisfy the body’s requirement for vitamin D, darker-skinned people will need more exposure to produce the same results. It is important for individuals with limited sun exposure to include good sources of vitamin D in their diet.
Technicals: Vitamin D helps maintain normal blood levels of calcium and phosphorus. Works with minerals to create strong bones and teeth, prevents colds used along with vitamins A and C, aids in absorption of vitamin A. One microgram of Vitamin D as cholecalciferol has 40 IU of vitamin D activity
Vitamin D acts more like a hormone than like a vitamin: The source of vitamin D is either through the diet or by the action of ultraviolet light on the precursor molecules in the skin. Vitamin D is converted to an intermediate form in the liver, then to an active form in the kidneys. From there it acts in the intestine, facilitating calcium absorption there. Vitamin D moves into the bone to assist normal bone formation and mineralization. testing
A dietary deficiency of vitamin D inhibits the production of a protein that binds calcium in the intestines, that prevents calcium from being absorbed, even in the presense of adequate calcium intake. Deficiencies of vitamin D are often found in the elderly and in women who have low intake of milk and receive inadequate exposure to sunlight.
Sources: Most people derive vitamin D from incidental exposure to ultraviolet rays from the sun. Egg yolk, fish, fish liver, tuna, milk, dairy products and fortified foods.
Synergist: Vitamin A, Choline, Vitamin C, Calcium, Phosphorus. Its precursor from plants are called ergosterol and the precursor from eating animal tissues is called 7-dehydrocholesterol.
Deficiencies Caused by: A deficiency of can occur when dietary intake is inadequate, when there is limited exposure to sunlight, when the kidney cannot convert it to its active form, or when someone cannot adequately absorb it from the gastrointestinal tract.
Signs or Symptoms of a Deficiency: Osteomalacia in adults; rickets in children. In children, its deficiency causes rickets, which results in skeletal deformities. In adults, its deficiency can lead to osteomalacia, which results in muscular weakness in addition to weak bones, deformity of bone and pathologic fractures..
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