Vitamin D (calciferolum) is an anti rickety vitamin, often called vitamin of the sun. Like vitamin A, belongs to a group of fat-soluble vitamins and it’s the only vitamin whose active form is a hormone. It is a regulator of calcium homeostasis in the body together with parathyroid hormone (RTN) regulates the concentration of calcium in plasma.
It can be synthesized by the body in the presence of sunlight; 7-dehidroholesterol that is present in the skin when exposed to sunlight is converted into vitamin D3. Further processing of this vitamin in the liver makes this vitamin active, and because it is fat soluble, it can be stored in fatty tissues and the liver.
Vitamin D improves the absorption of calcium and phosphates in the body, and is necessary for normal growth and bone mineralization. There are two main forms of vitamin D.
D2 – ergocalciferol
D3 – cholecalciferol
Ergosterol (provitamin for D2) has herbal origin, while 7 dehidrokalciferol (provitamin for D3) has animal origin.
Vitamin D is not only important in maintaining bone density; it plays an important role in many other neurological and cellular functions that require calcium, production of monocytes, as well as normal growth and development of children.
Importance of Vitamin D
The main role of vitamin D is to help the body use calcium and phosphorus, which are important for the health of bones and teeth. Its role is to control the quantity of absorbed calcium from food and how much of that amount will be incorporated into the bones.
Today it is known that this vitamin helps in the prevention and treatment of diseases such as:
High blood pressure,
It strengthens the immune system,
Maintain brain health in older years of life.
But recent studies show a much larger role in the health of vitamin D, described in 12 Little Known Benefits of Vitamin D.
How much vitamin D we need?
The required daily amount of vitamin D is expressed in the Adequate Intake (AI) and not with the RDA (recommended daily amount), due to the inability to accurately determine the production of this vitamin when our body is exposed to sunlight. (AI) determines the amount that should be entered with food to maintain normal body functions. Measured in international units it is 40 IU in microgram.
Daily recommended intake for vitamin D is 200-400 units (5-10μg). Pharmacological dose for each patient is individually determined.
Sources of vitamin D
Primary way for synthesis of vitamin D in the body is exposure to sunlight. In the food most vitamin D is found in fish oil and fish meat (Oleum jecoris aselli and Oleum jecoris hypoglossi), as well as it can be found in butter, eggs, milk and dairy products enriched with vitamin D, yeast, liver, gall bladder, etc., while on the market most of the supplements of vitamin D are in the form of ergocalciferol.
Vitamin D deficiency
Deficiency of this vitamin is characterized by hypercalcemia, hypophosphatemia or general demineralization of bone, bone pain, spontaneous fractures and muscle pain. Lack of vitamin D leads to decreased absorption of calcium and phosphorus. Children may get behind the growth and deformation of bones, especially the long bones, or the occurrence of a disease called rickets. Deficiency in adults is rare and occurs in the form of osteomalacia and muscle spasms.
Risk factors for vitamin D deficiency
Most likely reason for the lack of vitamin D is low exposure to sunlight. This occurs in people who do not go out often or where weather conditions do not allow appropriate exposure to sunlight.
Other risk factors are excessive use of alcohol, prematurely born babies, people with diseases of the liver and kidneys, people who take drugs as anticonvulsants, corticosteroids and cholestyramine, and others.
Vitamin D Toxicity
Acute or long-term use of vitamin D can lead to a number of clinical symptoms resulting from disorders of calcium metabolism. Initial signs and symptoms of vitamin D toxicity are associated with the occurrence of hypercalcemia (fatigue, headaches, digestive problems, weight loss, anemia, and sometimes depression and hypertension). Extra deposition of calcium in the body can also lead to kidney and pancreas diseases.
If active form of vitamin D is taken in excessive amounts, outcome can be fatal, and because of that hypervitaminosis with this vitamin is considered as one of the most toxic.