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| Space-filling of the cholecalciferol molecule (vitamin D3), C 27 H 44 O, as found in the crystal structure. X-ray crystallographic data from J. Org. Chem. (1976) 41, 3476–3478. Model constructed in CrystalMaker 8.1. Image generated in Accelrys DS Visualizer. (Photo credit: Wikipedia) |
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| English: Overview of calcium regulation (See Wikipedia:Calcium in biology). To discuss image, please see Talk:Human body diagrams References Page 1094 (The Parathyroid Glands and Vitamin D) in: Walter F., PhD. Boron (2003). Medical Physiology: A Cellular And Molecular Approaoch, 1300, Elsevier/Saunders. (Photo credit: Wikipedia) |
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| In some countries, milk and cereal grains are fortified with vitamin D. (Photo credit: Wikipedia) |
Vitamin D is the common name for a group of sterol compounds with biological activity of cholecalciferol. Is fat soluble, resistant to high temperature oxidation in an alkaline environment, but is decomposed under the influence of excessive UV radiation.
A SOURCE OF VITAMIN D
From a nutritional point of view, the two most important forms of prowitaminowe is cholecalciferol - present in animal products, especially fatty fish, and milk and milk products, and ergocalciferol - formed under the influence of sunlight in plant foods (mainly in yeast and fungi). Their biological activity is the same.
Cholecalciferol can also be produced in the skin from 7-dehydrocholesterol under the influence of exposure to sunlight, specifically ultraviolet B (UVB). Its endogenous synthesis in favorable conditions can provide 80-90% of the daily requirement of the body. Perhaps as much as 10 - to 15-minute exposure of the entire surface of the body is sufficient to synthesize adequate amounts of vitamin. D, cholecalciferol, however, the skin is formed only when it is directly exposed to the UV rays. Leather covered even thin clothing or sunscreen application of high blocking this mechanism.
Unfortunately, Poland is located in the geographical area in which the synthesis of the skin may be insufficient, especially in autumn and winter (October to May). When the days are short and cloudy, the outdoor temperature low enough that the residence time in the fresh air is limited, and warm clothes tightly opatula body - skin synthesis drops to zero. Even in the warm and sunny summer days cutaneous synthesis depends on air pollution limiting penetration of radiation through the atmosphere, the use of sunscreen and skin pigmentation.
Exposure to sunlight is limited as in the case of elderly people with mobility problems, patients staying in hospitals and detention centers. Part of the problem also applies to children.
The biologically active form of vitamin D, necessary for intestinal calcium transport system is 1,25 (OH) 2 D (calcitriol), which is synthesized by a two-step hydroxylation of food and provitamins endogenous synthesis-ergokalcyferolu (D 2) and cholecalciferol (D 3). The first stage of the biosynthesis of the active form of vitamin. D takes place in the liver, where the enzymatic hydroxylation of the 25th carbon atom, and the next - the kidneys, the first carbon atom and is formed calcitriol (1,25-dihydroxycholecalciferol).
THE ROLE OF VITAMIN D
Vitamin D is primarily required for proper absorption of calcium and phosphate from the gastrointestinal tract, and also inhibits their loss from the body by the kidneys, and that determines the strong bones and healthy teeth. In addition, regulates the level of calcium in the blood, maintains optimal bone mineral density, it is also essential for the proper functioning of the muscular, nervous, immune and endocrine systems.
EFFECTS OF DEFICIENCY or overdose
When the body lacks wit. D, calcium absorption in the intestinal tract is very low and to keep the blood level of normal body begins to take calcium from the bones, which leads to rickets. Rickets is formed between 3 and 24 months of age, and the most at risk are children born prematurely, the children who are growing fast, little staying in the open air and have a poor appetite, making vitamin intake. D and calcium and phosphorus is deficient.
The first symptoms of rickets are irritability, anxiety, sweating head during feeding and lack of appetite. Longer-term vitamin deficiency. D leads to the softening of the occipital bone, delayed fouling ciemiączek, emphasize the frontal, the distortion of the ribs. Arched legs bent in the shape of the letter X or O, there is a delayed eruption of teeth and deterioration resistance. But keep in mind that no single symptom can not be the basis for the diagnosis of rickets. Always require a doctor's decision on the basis of the relevant research and biochemical analysis, among others. assessment of the concentration of 25 (OH) D levels (as the best indicator of the amount of substrate available for synthesis of active hormone calcitriol in the kidney and other tissues), calcium and phosphorus in the blood.
Vitamin A deficiency. D in adolescents and adults, leading to osteomalacia and osteoporosis. The excessive intake of vitamin D can cause kidney stones, kidney failure, constipation, nausea, easy fatigue is excessive thirst and renal excretion. In children, vitamin overdose. D leads to a delay in development.
WAY TO HEALTHY BONES AND TEETH - FROM EARLY Childhood
. D vitamin is essential for life, but especially to take care of the proper intake and appropriate supplementation during active growth and development, they grow and strengthen the bones and teeth. The infant is born with a supply of wit. D for 4-5 weeks, it has a much smaller stocks. Breastfed infants vitamin supplementation. D starts from 3 weeks of age and given prophylactically throughout the year, regardless of the weather. Modified milk-fed infants usually receive a sufficient dose of wit. D, provided that they receive the right amount of milk.In our climate, with limited exposure to the sun - especially in autumn and winter, in the cities, where the degree of exposure to the sun is limited due to the high installation and greater air pollution, skin synthesis of cholecalciferol is sufficient. There should be sufficient dose of wit. D, preferably supplied from a food or as a supplement in pharmaceutical preparations.
FOOD RICH IN WIT. D
The main natural sources of vitamins. D is oily fish (eg salmon, mackerel, herring, sardines), milk and dairy products, butter, egg yolk and liver, but vitamin intake. D of the food products is not sufficient.
In the traditional, well-balanced diet, vitamin intake. D can be as high as 3.75 to ALG / day, provided that frequent consumption of oily fish. Keep in mind that the contents of wit. D in products such as milk, butter and egg yolk may be subject to seasonal fluctuations.
The research conducted by the Institute Danone in 2007 on a representative group of 400 children aged 4 years showed that the average daily intake of vitamins. D was 2.5 algae, ie only 25% of the recommended intake for this age. Major deficiency (vitamin D intake of less than 2/3 the recommended values) was observed in over 95% of children.
An important supplement to the diet of wit. D products are fortified with vitamin D. The vitamin . D is mainly supplemented infant products - milk and meal modified instant and margarine. You can also buy drinking milk fortified with certain vitamins and minerals, but in other European countries and the United States to supplement assortment wit. D in the diet is much broader. It is also added to fruit juices, cereals, and other popular foods.
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