Vitamin D is perhaps the most discussed substance in both medicine and dietetics. The need for sufficient consumption occurs in a person before birth, because if the expectant mother is deficient in vitamin D, the newborn may later have serious health problems. And in adult life, this substance can not be replaced by any synthetic additives and pills. Of course, the modern pharmaceutical market offers tablet forms of an analog of the vitamin, however, its properties, metabolism, and functions are significantly inferior to natural ones, not to mention possible side effects, allergic reactions, overdoses, and other complications. Therefore, natural sources of vitamin D are mandatory in the daily diet of everyone who seeks to maintain their health for many years. Where does this substance, which is necessary for the normal functioning of the body, come from, how is it absorbed and what functions it performs?
Vitamin D: name and properties
Vitamin D is not one, but a whole group of substances similar in structure, function, and biological activity. This list includes:
- Ergocalciferol, or form D2. This vitamin was first isolated from yeast.
- Ergosterol, provitamin D2-can be found in extracted forms of yeast-like forms, fungi, etc.
- Cholecalciferol, or form D3. Perhaps the most common form of vitamin D is Synthesized in the tissues of living organisms (including, of course, humans) under the influence of the ultraviolet spectrum of sunlight.
- 22, 23-dihydroergosterol, or form D4.
- Sitocalciferol, or form D5. This vitamin is also known as 24-ethylcholecalciferol, extracted from wheat oil extract.
- Stigma-calciferol, or form D. Scientific name “22-dihydroethylcalciferol”.
In medicine, vitamin D has a generic name – “calciferols”. However, this term most often refers to two forms of this vitamin-D2 and D3. Despite the variety of forms, these two varieties are of particular importance to humans. If the first enters the human body from the outside, that is, with food, and only then is absorbed in the intestine and enters the blood, the second is synthesized by the body itself under the influence of sunlight. It is vitamin D3 that provides the body’s needs in most cases, however, in some cases, it is simply impossible to do without an additional supply of the D2 form.
Vitamin D in the body is absorbed only in combination with vegetable oils, since it belongs to the fat-soluble group of substances. Like all components that react with organic solvents, it is deposited in the liver and can be extracted from it in cases of temporary deficiency. This property is especially important in winter, when the amount of sunlight and natural sources of calciferol decreases; getting enough vitamin D in the summer, you can not worry about its deficit in winter.
What is vitamin D for?
The functions of calciferol in the body are simply huge. This versatility is explained by the fact that the substance acts not only as a vitamin, but also as a hormone. Entering the digestive tract, it is absorbed in the small intestine, reacting to the effects of bile. Most of the vitamin D is adsorbed in the middle part of the small intestine, while the rest remains in the iliac part.
The main function of calciferol is read from the context, because vitamin D has a rather “talking” name: normal mineral metabolism in General and the absorption of calcium in particular is impossible without a sufficient amount of this substance. Calciferol regulates the deposition of calcium in bone tissue, thereby preventing its softening and subsequent serious injuries of the musculoskeletal system. When the molecules of Ca, Mg and phosphates are metabolized, it accelerates all metabolic processes, and also has a positive effect on the permeability of intestinal epithelial cells for Ca and P. And if the lack of phosphorus is rare, then the lack of calcium in the body is a fairly common phenomenon and, unfortunately, significant.
As a hormone, vitamin D in the body also affects the metabolism of calcium: entering the cells of the small intestine, it inhibits the synthesis of a carrier protein, which subsequently binds to calcium and transports it, and in kidney and muscle cells acts as a catalyst in the processes of reabsorption of Ca molecules.
However, calcium metabolism is not the only function of this substance: vitamin D has a fairly wide application. Thus, calciferol directly affects the body’s immune responses, reducing the risk of dermatological problems. A normal amount of vitamin is the best prevention of cardiovascular pathologies, including atherosclerosis, heart rhythm disorders, regular increase in blood pressure and associated hypertensive crises.
Vitamin D: daily use
The daily requirement of calciferol depends not only on age and gender, but also on the peculiarities of geographical location, belonging to a certain race and the state of the body. For example, people who experience a lack of sunlight, the need to get vitamin D from the outside increases significantly. This category of persons includes:
- people who lead a nocturnal lifestyle (working the night shift or preferring night walks to daytime ones);
- living in countries that are geographically located in high geographical latitudes;
- bedridden patients who are physically unable to regularly be outdoors;
- residents of cities (usually megacities) that have a particularly polluted atmosphere that does not pass the full spectrum of ultraviolet rays: even if there is enough sun in such an area, the necessary waves will be filtered out by chemical compounds that pollute the air.
The color of the skin also affects the natural synthesis of vitamin D: the darker it is, the less substance is formed under the influence of ultraviolet light. Similarly, the need for calciferol changes with age, because in older people, the body’s ability to convert provitamins to calciferol is significantly lower.
Lack of vitamin D in the body
Hypovitaminosis D scares young mothers almost to shiver: after all, the growing body needs calcium, which means that vitamin D. If it is not enough, the crumbs can develop rickets, which is accompanied not only by serious changes in the skeleton, but also by damage to internal organs. Especially the heart and lungs suffer, because they are located in the chest, which begins to deform in the first place. But even knowing what vitamin D is needed for a newborn, it is not necessary to stuff it with synthetic additives almost from the first days; it is enough to make sure that he is in the fresh air every day and receives a sufficient portion of sunlight. If the child is breastfed, the mother also needs regular walks in the daytime: after all, with breast milk, a useful substance will be delivered to the baby.
Low levels of vitamin D in the blood are dangerous not only in infancy, but also in older age. So, if there is a lack of calciferol, adults can develop a dangerous bone disease – osteoporosis. It is characterized by softening of the bones, their pathological fragility and deformation. This means that even the slightest injury, which in a healthy person would cause maximum bruising, can lead to complex fractures, which will also heal extremely slowly. Especially serious are injuries to the hip neck, spine, and shrapnel fractures: it is very difficult to recover from them.
In addition, hypovitaminosis D is associated with the development of diabetes, especially in adolescence, as well as with disorders of thyroid function, adequate blood clotting, and the development of psoriasis. Among other things, research is currently underway to confirm that calciferol reduces the risk of cancer.
Is excessive vitamin D dangerous
Despite its undoubted benefits, large amounts of calciferol can cause serious damage to the body. If the level of calcium in the blood increases, the kidneys, heart, and circulatory system may be damaged. At the initial stages of hypervitaminosis D will manifest the following symptoms:
- the classic picture of intoxication: apathy, lethargy, lack of appetite, dizziness;
- painful sensations in the joint area, as well as muscle spasms;
- persistent headache.
If you do not take action, the clinical picture will be supplemented by fever, pressure surges, bradycardia and convulsions.
However, a pathologically high content of vitamin D in the blood is a rare phenomenon. Most often, it occurs when long-term or excessive use of synthetic additives. It is impossible to face hypervitaminosis when sunbathing and regularly consuming products enriched with calciferol.
Vitamin D: contained in the following products
As a rule, ergocalciferol enters the body from food. Its share in providing the body with vitamin D is negligible and is about 10 % of the total human need, however, it is not necessary to completely exclude fortified products from the diet: they can become a tangible support for the body, especially in the autumn-winter period, when the number of cloudy days increases. What products should I pay attention to first?
Foods containing the highest amount of vitamin D
Forest mushrooms. The first positions in this list deservedly received chanterelles. These unpretentious mushrooms grow almost everywhere, however, it is not necessary to collect them in the city and along highways: they accumulate a lot of harmful substances, including toxic compounds from exhaust gases, heavy metals, but chanterelles grown in the forest will be extremely useful. It is noteworthy that the amount of vitamin D in them does not decrease after salting or drying. This means that you can prepare dried chanterelles for the winter and pamper your loved ones with fragrant and healthy mushroom dishes all year round. Of course, yogis believe that this type of product negatively affects the state of energy, but if you are, for example, at the stage of initial vegetarianism and experiment with recipes, then a few mushrooms are unlikely to hurt you much.
Herbage. Large amounts of ergocalciferol can be found in parsley, dandelion, nettle, horsetail, and alfalfa. Some of these herbs can be used as the main ingredient for preparing fortified dishes, while others are only good as condiments. For example, in the summer, doctors recommend regularly preparing soup with nettle: this unique plant contains many useful components, including vitamin D. dandelions often make delicious jam, which is also perfectly stored in the refrigerator. But parsley can only be used as a spicy herb, but you can put it in almost any dish, whether it’s a soup, salad or side dish.
Vegetable oil. Calciferol can be obtained from wheat, corn, sunflower, olive, and other types of oils. However, it is not necessary to abuse the heat treatment in this case: when frying, many useful components of extracted oil extracts disintegrate. Much better to use them as a salad dressing.
However, it is not necessary to limit the list to these products: today on store shelves you can find a lot of all kinds of products specially enriched with vitamin D. and although this form can be called natural only with a stretch, with a lack of sunlight and other sources, this can be the optimal solution to the problem.
The importance of calciferol for the body is extremely high at any age. This vitamin provides calcium metabolism, helps strengthen the immune system and is involved in dozens of other physiological processes. However, even if you know which foods contain vitamin D, you will not be able to provide them to the body in full: only regular exposure to the fresh air, long walks in Sunny weather and a healthy moderate tan will help to provide a supply of calciferol for the whole year. A comprehensive approach that includes proper nutrition and a healthy lifestyle will help you feel refreshed for many years and avoid visiting doctors.