Vitamin D: Understanding the Benefits.

Vitamin D is the general name given to a group of fat-soluble compounds that are essential for maintaining mineral balance in the body. It is also known as calciferol and antirachitic Vitamin D. The main forms are known as vitamin D2 (ergocalciferol: of plant origin) and vitamin D3 (cholecalciferol: of animal origin).

Given that cholecalciferol is synthesized in the skin through the action of ultraviolet light on 7-dehydrocholesterol, a cholesterol derivative widely distributed in animal fat, vitamin D does not conform to the classic definition of a vitamin, now being considered a pre-hormone.

Nevertheless, given the number of factors influencing synthesis, such as latitude, season, air pollution, exposed skin area, pigmentation, age, etc., vitamin D is recognized as an essential dietary nutrient.

Rich natural sources of vitamin D include fish liver oils and saltwater fish, such as sardines, herring, salmon, and mackerel. Eggs, meat, milk, and butter also contain small amounts. Plants are poor sources, and fruits and nuts contain no vitamin D. The amount of vitamin D in human milk is insufficient to cover infant needs.

Vitamin D is relatively stable in foods; storage, processing, and cooking have little effect on its activity, although in fortified milk, up to about 40% of added vitamin D may be lost as a result of light exposure.

Cholestyramine (a resin used to stop the reabsorption of bile salts) and mineral oil-based laxatives inhibit the absorption of vitamin D from the intestine. Corticosteroids, anticonvulsant drugs, and alcohol can affect calcium absorption by reducing the response to vitamin D. Animal studies also suggest that anticonvulsant drugs stimulate liver enzymes, leading to increased breakdown and excretion of this vitamin.

Patients treated with thiazide diuretics or magnesium-containing antacids should avoid taking high doses of vitamin D due to the increased risk of hypercalcemia or hypermagnesemia, respectively. It has also been found that women taking oral contraceptives have slightly elevated blood calcitriol levels.

Vitamin D is essential for homeostasis. Classically, it is known to be necessary for the absorption of calcium and phosphorus in the large intestine, for their mobilization from bones, and their reabsorption in the kidneys. Through these three functions, vitamin D plays an important role in ensuring the proper functioning of muscles, nerves, blood clotting, immunity, cell growth, and energy utilization. It is thought that mineral deposition in the skeleton is the result of high concentrations of calcium and phosphorus in the blood, thus being only indirectly due to the action of vitamin D.

To perform its biological functions, calcitriol - ACTIVE VITAMIN D, like other hormones, binds to specific receptors on target cells. Such receptors have been found in a wide variety of tissues. It has been proposed that vitamin D is also important for insulin and prolactin secretion, immune and stress responses, melanin synthesis, and for the differentiation of skin and blood cells.

Modern medicine daily discovers new functions for the distinguished vitamin D, now possessing hormonal characteristics, and if deficient, it should be replenished. Learn more in Preventive Medicine.

Among the first symptoms of vitamin D deficiency are reduced serum calcium and phosphorus levels and increased alkaline phosphatase activity. This can be accompanied by muscle weakness (e.g., leg pain) and tetany, as well as increased infection risks. Children may show nonspecific symptoms such as restlessness, irritability, excessive sweating (hyperhidrosis), and decreased appetite. Hypovitaminosis D contributes to brittle bones in the elderly and the development of osteoporosis.

The most widely recognized manifestations of vitamin D deficiency are rickets (in children) and osteomalacia (in adults). Both are characterized by mineral loss from bones, resulting in skeletal deformities, such as bowed legs in children. The ends of the long bones in both arms and legs are involved, and growth may be retarded. Rickets also results in inadequate mineralization of tooth enamel and dentin.

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