Vitamin D, calciferol, is a fat-soluble vitamin. It is found in food, but also can be made in your body after exposure to ultraviolet rays from the sun. Vitamin D exists in several forms, each with a different activity. Some forms are relatively 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.
The major biologic function of vitamin D is to maintain normal blood levels of calcium and phosphorus. 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 -- skeletal diseases that result in defects that weaken bones.
Vit B Complex
Key Functions of Vitamin D
Vitamin D is crucial for the development of healthy bones and teeth. Without it, the body cannot build or maintain strong bones.
Vitamin D is a fat-soluble vitamin that plays a role in controlling calcium absorption, which affects bone development and is also essential for blood clotting.
When vitamin D is in short supply in the body, less calcium is absorbed from food, and blood levels have to be maintained by taking calcium from the bones.
Food Sources of Vitamin D
milk (fortified)
Cod liver oil
cheese
whole eggs
liver
salmon
herring
mackerel
sardines
tuna
fortified margarine
The skin can synthesize vitamin D if exposed to enough sunlight on a regular basis.
Recommended Daily Usage of Vitamin D
The Recommended Dietary Allowance (RDA) is the average daily dietary intake level that is sufficient to meet the nutrient requirements of nearly all (97-98%) healthy individuals in each life-stage and gender group. Unlike many other nutrients, there is insufficient evidence to establish an RDA for vitamin D.
Ages 19-50: 200 International Units (IU) Ages 51-69: 400 IU Age 70 and older: 600 IUThe best way to get the daily requirement of essential vitamins is to eat a balanced diet that contains a variety of foods from the food guide pyramid.
Vitamin D is also known as the "sunshine vitamin" because the body manufactures the vitamin after being exposed to sunshine. Ten to 15 minutes of sunshine 3 times weekly is enough to produce the body's requirement of vitamin D.
Specific recommendations for each vitamin depend on age, gender, and other factors (such as pregnancy). In general, those over age 50 need slightly higher amounts of vitamin D than younger persons.
Nutritional Safety
A deficiency of vitamin D can occur when dietary intake of vitamin D is inadequate, when there is limited exposure to sunlight, when the kidney cannot convert vitamin D to its active form, or when someone cannot adequately absorb vitamin D from the gastrointestinal tract.
Vitamin D deficiency can lead to osteoporosis in adults or rickets in children.
Too much vitamin D can make the intestines absorb too much calcium. This may cause high levels of calcium in the blood. High blood calcium can lead to calcium deposits in soft tissues such as the heart and lungs. This can reduce their ability to function.
Kidney stones, vomiting, and muscle weakness may also occur if you have too much vitamin D.
My next article entitled "The Function of Vitamin K in our Life" will examine the role of Vitamin K in good nutrition.
See you on the Beaches of the World,
Kevin McNabb