A group of fat-soluble, prohormone vitamin, the two major forms of which are vitamin D2 (or ergocalciferol) and vitamin D3 (or cholecalciferol). Vitamin D obtained from sun exposure, food, and supplements is biologically inert and must undergo two hydroxylations in the body for activation. Vitamin D is essential for promoting calcium absorption in the gut and maintaining adequate serum calcium and phosphate concentrations to enable normal growth and mineralization of bone and prevent hypocalcemic tetany. Deficiency causes rickets and osteomalacia. Vitamin D has other roles in human health, including modulation of neuromuscular and immune function, reduction of inflammation and modulation of many genes encoding proteins that regulate cell proliferation, differentiation, and apoptosis.
Soluble in fat, stable to heat and oxidation, and formed from irradiation of sterols. Essential for enhancement of calcium and phosphorous from the intestinal tract, prevents rickets (chiefly affecting bones and teeth). Found in cod liver oil, halibut fish, sardines, mackerel, and other canned fish.
A vitamin occurring in the body as or provitamin. Provitamin D is a form of cholesterol occurring in animals and ergosterol in plants and is changed to vitamin D upon exposure to ultraviolet light.
A vitamin which is soluble in fat and is found in butter, eggs and fish. It is also produced by the skin when exposed to sunlight. It helps in the formation of bones, and lack of it causes rickets in children.
A fat-soluble vitamin, chemically called calciferol, important for bone formation, and in ensuring calcium deposition in bones. It can be produced in the skin by exposure to the sun and is present in fish liver oils.
Like vitamin A, vitamin D is not a single compound. There is no D1 because when the vitamins were originally isolated and identified, the compound identified as D1 turned out to be a mixture of the other D vitamins rather than a separate entity.
The active form of vitamin D, a fat-soluble vitamin synthesized from cholesterol, is known as calcitriol or 1,25-dihydroxycholecalciferol. Vitamin D is important for cell differentiation and immune function but is primarily known for its roles in calcium metabolism. These roles include enhancing calcium absorption at the small intestine, increasing calcium retention by the kidney, and elevating calcium mobilization from the bone. Vitamin D deficiency is linked to bone demineralization, which can produce rickets in children and osteomalacia and possibly osteoporosis in adults. Much of our requirement for vitamin D can be acquired by exposure of the skin to sunlight, which allows for production of an inactive form of vitamin D from cholesterol that can be metabolized by the liver and then kidney to the active form. Vitamin D is found in some fatty animal foods, but the majority of dietary vitamin D is obtained from fortified dairy foods. There are no known mechanisms by which vitamin D supplementation may enhance performance of athletes. Furthermore, vitamin D is considered quite toxic at high doses.
A vitamin existing in several forms, some from plant sources, some from animals, all of which are vital to the absorption of calcium and phosphorus for bone formation. In the body, vitamin D is converted to a substance that acts something like a hormone. Severe lack of the vitamin in children leads to the deficiency disease called rickets, which results in skeletal deformities, including bowed legs, deformed spine, “pot-belly” appearance, and flat feet; in adults, vitamin D deficiency leads to osteomalacia. Excess vitamin D is stored in the body, and too much of it can cause nausea, weight loss, weakness, excessive urination, and, more seriously, hypertension, calcification (hardening) of soft tissues, including the blood vessels and kidneys, and often bone deformities and multiple fractures. Vitamin D is abundant in canned and fresh fish (especially from salt water), egg yolk, and foods fortified with the vitamin, such as milk and margarine. Such fortified foods are especially important to infants and children with chronic illnesses; others who have normal outside activities usually have enough vitamin D, since it is formed in the skin by ultraviolet rays.
Several chemicals (e.g., calciferol) contained naturally in fish-liver oil and egg yolk, and essential to health, especially the absorption of calcium and phosphorus.
Cholecalciferol, a fat-soluble vitamin essential for the formation of bones and teeth and for the absorption of calcium and phosphorus. A deficiency of vitamin D can cause bone diseases such as osteoporosis and rickets. Good dietary sources of vitamin D include organ meats, fish liver oils, egg yolks, and saltwater fish such as salmon, sardines, and herring. Because relatively small amounts of vitamin D are naturally available, dairy products, cereals, and breads are usually fortified with it. Exposure to sunlight enables the skin to manufacture vitamin D. As little as lo minutes of exposure to sunlight may produce sufficient quantities of vitamin D to maintain bone strength.
A fat-soluble vitamin that enhances the absorption of calcium and phosphorus from the intestine and promotes their deposition in the bone. It occurs in two forms: ergocalciferol (vitamin D2, calciferol), which is manufactured by plants; when the sterol ergosterol is exposed to , ultraviolet light, and cholecalciferol (vitamin D3), which is produced by the action of sunlight on 7-dehydrocholesterol, a sterol widely distributed in the skin. A deficiency of vitamin D, either from a poor diet or lack of sunlight, leads to decalcified bones and the development of rickets and osteomalacia. Good sources of vitamin D are liver and fish oils. The recommended daily intake is 10 μg for a child up to five years and 2.5 μg thereafter. Vitamin D is toxic and large doses must therefore be avoided.
One of several vitamins having antirachitic activity. The vitamin D group, which is fat-soluble, includes D2 (calciferol), D3 (irradiated 7-dehydrocholesterol), D4 (irradiated 22-dihydroergosterol), and D5 (irradiated dehydrositosterol). It is essential in calcium and phosphorus metabolism; consequently, it is required for normal development of bones and teeth. The recommended daily allowance is 10 pg. The stability of this vitamin is not affected by oxidation; heat, unless over 100°C (212°F); or long-continued cooking. A deficiency of vitamin D causes imperfect skeletal formation, bone diseases, rickets, and caries.
Enables the body to properly absorb and use calcium, the element needed for proper bone development and maintenance. Vitamin D also promotes rapid healing of the skin.
Vitamin D, an essential group of fat-soluble nutrients, plays a vital role in maintaining the health of bones, teeth, and various physiological processes. This particular vitamin can be derived from certain food sources, as well as synthesized within the body through the influence of ultraviolet radiation.
The umbrella term for a set of compounds that assist in maintaining the equilibrium of phosphate and calcium levels in the body, facilitate the absorption of calcium in the digestive tract, and support the development of robust bones and teeth.
Rich sources of vitamin D encompass oily fish, liver, and the yolk of eggs, and the vitamin is additionally fortified in margarines. Within the body, vitamin D is produced when ultraviolet light interacts with a specific chemical found in the skin.
A lack of vitamin D can arise in people with inadequate diets, in prematurely born infants, and in those who have limited exposure to sunlight. It can also be due to issues with nutrient absorption. Additional contributing factors can be liver or kidney diseases and certain genetic anomalies. Extended use of specific medications, like the anticonvulsant phenytoin, may also induce a deficiency. In young children, this deficiency can result in the bone condition known as rickets, while long-term deficiency in adults can lead to osteomalacia.
Consuming too much vitamin D can result in hypercalcemia, a condition characterized by unusually high levels of calcium in the blood. This could also lead to irregular deposits of calcium in soft tissues, kidneys, and the walls of blood vessels. In children, excessive vitamin D intake may hinder normal growth.
This vitamin, present in cod liver oil and milk, is essential in the diet, particularly for growing children. Its deficiency can lead to the development of rickets.
This vitamin is present in cod liver oil and milk. Insufficient intake of this vitamin in one’s diet, particularly among growing children, can lead to the development of rickets.