Vitamin D and its role in the body

Vitamin D and its role in the body

I. What is vitamin D? Definition and various forms.

Vitamin D is a fat -soluble vitamin that plays a critical role in maintaining bones, immune function and general well -being. Contrary to widespread opinion, vitamin D is not just a vitamin, but rather a runner, that is, the predecessor of the hormone. It has a unique ability to synthesize in the skin under the influence of sunlight, which distinguishes it from most other vitamins that must be obtained with food.

There are several forms of vitamin D, but the two most significant for human health is vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol).

• Vitamin D2 (ergocalciferol): This form of vitamin D is synthesized by plants, mushrooms and yeast under the influence of ultraviolet radiation. It is often used as an additive and can be obtained from enriched products. Vitamin D2 is less effective in increasing the level of vitamin D in the blood than vitamin D3.

• Vitamin D3 (cholecalciferol): This form of vitamin D is synthesized in the skin of humans and animals under the influence of sunlight (ultraviolet radiation b). It is also contained in some products of animal origin, such as fatty fish (salmon, tuna, mackerel) and egg yolk. Vitamin D3 is considered more effective in increasing and maintaining the level of vitamin D in the blood compared to vitamin D2.

Both forms of vitamin D, D2 and D3 are metabolism in the body to form an active form of vitamin D, calcitriol (1.25-dihydroxyvitamin D). This process occurs in two stages: first in the liver, where vitamin D turns into 25-hydroxyvitamin D [25(OH)D]also known as calciol. Then, in the kidneys, where calciol turns into calcitriol, a biologically active form of vitamin D.

Level 25 (OH) D in the blood is the main indicator of the status of vitamin D in the body. It is used to assess the deficiency of vitamin D and monitor the effectiveness of treatment.

II. Vitamin D synthesis in the skin: factors affecting production.

The synthesis of vitamin D in the skin is a complex process that depends on many factors that can significantly affect the amount of vitamin D produced by the body. Understanding these factors is extremely important to optimize the production of vitamin D and prevent deficiency.

• Intensity and duration of solar exposure: Ultraviolet radiation B (UVB) is a key factor in the synthesis of vitamin D. UVB rays penetrate the skin and convert 7-dehydrocholesterol into previtamin D3, which then turns into vitamin D3. The intensity of UVB radiation varies depending on the time of year, time of day and geographical latitude. In the winter months and in regions located far from the equator, the intensity of UVB radiation can be insufficient for the effective synthesis of vitamin D.

The duration of the sun also affects the production of vitamin D. As a rule, it is enough to be in the sun with open hands, legs and face for 10-15 minutes a day from 10 a.m. to 3 p.m., when the UVB radiation is most intense. However, it must be borne in mind that a long -term stay in the sun without protection can increase the risk of skin damage and the development of skin cancer.

• Skin pigmentation (melanin level): Melanin is a pigment responsible for the color of the skin, hair and eyes. It acts as a natural sunscreen, absorbing UVB radiation. People with darker skin have more melanin, which reduces their ability to produce vitamin D under the influence of sunlight. They may need a longer stay in the sun or taking vitamin D additives to maintain an adequate level of vitamin D in the blood.

• Age: With age, the ability of the skin to produce vitamin D is reduced. This is due to a decrease in the amount of 7-dehydrocholesterol in the skin, the predecessor of vitamin D3. Older people also often spend less time in the open air, which further reduces their exposure to sunlight.

• Use of sunscreen: Sunscreen cream blocks UVB radiation, preventing the synthesis of vitamin D in the skin. Although the sunscreen is important to protect against skin and cancer of the skin, its excessive use can reduce the production of vitamin D. It is recommended to apply sunscreen to those areas of the skin that are not exposed to the sun for the necessary time to synthesize vitamin D.

• Geographical breadth and time of the year: The geographical breadth and time of the year have a significant impact on the intensity of UVB radiation. In regions located far from the equator, the angle of fall of sunlight is more acute, which leads to a weakening of UVB radiation. In winter, when the sun is below the horizon, UVB radiation can be insufficient for the effective synthesis of vitamin D.

• Cloud and air pollution: Clouds and air pollution can absorb and dissipate UVB radiation, reducing its intensity and reducing the production of vitamin D in the skin.

III. Vitamin D metabolism: from skin to active shape.

After the synthesis in the skin or vitamin D, vitamin D is not biologically active. He must go through two stages of metabolism to turn into an active form, calcitriol (1.25-dihydroxyvitamin D).

• First stage: hydroxylation in the liver: Vitamin D (D2 or D3) is transported to the liver, where it is hydroxylating under the action of the 25-hydroxylase enzyme. As a result of this process, 25-hydroxyvitamin D is formed [25(OH)D]also known as calciol. Calcidia is the main form of vitamin D, circulating in the blood, and is used to assess the status of vitamin D in the body.

• The second stage: hydroxylation in the kidneys: Calcidiol is transported to the kidneys, where it is subjected to the second stage of hydroxylating under the influence of 1-alpha-hydroxylase enzyme. As a result of this process, 1.25-dihydroxyvitamin D is formed [1,25(OH)2D]also known as calcitriol. Calcitriol is a biologically active form of vitamin D and is associated with vitamin D (VDR) receptors in various body tissues, having its many effects.

The activity of the 1-alpha-hydroxylase enzyme in the kidneys is regulated by various factors, including the level of calcium in the blood, the level of parathormone (PTH) and the level of phosphates. The low level of calcium in the blood stimulates the production of PTG, which, in turn, activates 1-alpha-hydroxylase and increases the synthesis of calcitriol. Calcitriol helps to increase the level of calcium in the blood by increasing calcium absorption in the intestines, reducing calcium removal by kidneys and stimulating the release of calcium from bones.

IV. Vitamin D functions in the body: effect on bones, immunity and other systems.

Vitamin D plays a key role in many vital processes in the body. Its main function is to maintain bone health, but it also has a significant impact on the immune system, cardiovascular system, nervous system and other organs and tissues.

• Bone health: Vitamin D is necessary for the absorption of calcium in the intestine. It helps the body absorb calcium from food and maintain an adequate level of calcium in the blood, which is extremely important for bone health. Vitamin D deficiency can lead to a decrease in bone density, osteoporosis and an increase in the risk of fractures. In children, vitamin D deficiency can cause rickets, a state characterized by bone deformation.

• Immune system: Vitamin D plays an important role in the regulation of the immune system. It helps to modulate the immune response, reducing the risk of developing autoimmune diseases and increasing resistance to infections. Vitamin D is involved in the activation of immune cells, such as T cells and B cells, and helps them fight pathogens. Studies have shown that vitamin D deficiency can increase the risk of infectious diseases such as flu and colds.

• Cardiovascular system: Vitamin D can have a positive effect on the health of the cardiovascular system. Studies have shown that vitamin D deficiency can be associated with an increased risk of developing cardiovascular diseases, such as hypertension, atherosclerosis and heart failure. Vitamin D helps regulate blood pressure, improves the function of the endothelium (inner vascular shell) and reduces inflammation in the vessels.

• Nervous system: Vitamin D plays an important role in the development and functioning of the nervous system. It is involved in the regulation of the growth of nerve cells, neurotransmission and the protection of nerve cells from damage. Studies have shown that vitamin D deficiency can be associated with an increased risk of developing neurodegenerative diseases, such as Alzheimer’s disease and Parkinson’s disease.

• Muscle function: Vitamin D is necessary to maintain normal muscle function. It helps maintain the strength and endurance of muscles, and also prevents muscle weakness and convulsions. Vitamin D deficiency can lead to myopathy (muscle weakness) and an increase in the risk of falls, especially in the elderly.

• Cellular regulation: Vitamin D is involved in the regulation of cellular growth and differentiation. It helps to control the growth and reproduction of cells, and also prevents the development of cancer cells. Studies have shown that vitamin D deficiency can be associated with an increased risk of developing certain types of cancer, such as colon cancer, breast cancer and prostate cancer.

• Other functions: Vitamin D also plays a role in regulating blood sugar, maintaining a healthy pregnancy and reducing the risk of developing some autoimmune diseases, such as multiple sclerosis and rheumatoid arthritis.

V. Sources of vitamin D: food, additives and sunlight.

There are three main sources of vitamin D: sunlight, food and additives. The best way to obtain vitamin D is a combination of these three sources.

• Sunlight: As mentioned earlier, the skin can synthesize vitamin D under the influence of UVB radiation. However, the amount of vitamin D produced by the skin depends on many factors, such as the time of year, time of day, geographical latitude, skin pigmentation and the use of sunscreen.

• Food: Vitamin D is contained in a small number of food. Good sources of vitamin D include:

  • Fat fish: Salmon, tuna, scubabria and herring – this is excellent sources of vitamin D.
  • Egg yolk: Egg yolks contain a certain amount of vitamin D, but its content can vary depending on the diet of chickens.
  • Enriched products: Many foods are enriched with vitamin D, such as milk, yogurt, orange juice and breakfast flakes.

• Supplements: Vitamin D additives are an effective way to increase vitamin D levels in the blood, especially for people who do not get enough vitamin D from sunlight or food. Vitamin D additives are available in two forms: vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). Vitamin D3 is considered more effective in increasing and maintaining the level of vitamin D in the blood compared to vitamin D2.

The choice of a source of vitamin D depends on individual needs and preferences. People with vitamin D deficiency are often recommended to take vitamin D additives under the supervision of a doctor.

VI. Vitamin D deficiency: causes, symptoms and consequences.

Vitamin D deficiency is a common condition that can have a negative effect on health. It occurs when the level of vitamin D in the blood is not high enough to maintain the normal functions of the body.

• Causes of vitamin D deficiency:

  • Insufficient stay in the sun: One of the main causes of vitamin D deficiency is insufficient stay in the sun, especially in the winter months and in regions located far from the equator.
  • Limited vitamin D consumption with food: Insufficient consumption of products rich in vitamin D can lead to vitamin D.
  • Vitamin D: violation of vitamin D: Some diseases, such as Crohn’s disease, celiac disease and cystic fibrosis, may disrupt vitamin D absorption in the intestines.
  • Obesity: Vitamin D is a fat -soluble vitamin, and in people with obesity vitamin D can linger in adipose tissue, which reduces its accessibility for the body.
  • Some drugs: Some drugs, such as glucocorticoids and anticonvulsants, can reduce the level of vitamin D in the blood.
  • Liver and kidney diseases: Diseases of the liver and kidneys can disrupt vitamin D metabolism and reduce the level of the active form of vitamin D in the blood.

• Symptoms of vitamin D:

  • Fatigue and weakness: One of the most common symptoms of vitamin D deficiency is fatigue and weakness.
  • Bone pain and muscles: Vitamin D deficiency can cause pain in bones and muscles, as well as muscle weakness.
  • Frequent fractures: Vitamin D deficiency can reduce bone density and increase the risk of fractures.
  • Reduced immunity: Vitamin D deficiency can weaken the immune system and increase susceptibility to infections.
  • Depression and bad mood: Some studies have shown that vitamin D deficiency can be associated with depression and poor mood.
  • Slow wound healing: Vitamin D deficiency can slow down the healing of wounds.
  • Hair loss: In some cases, vitamin D deficiency can cause hair loss.

• The consequences of vitamin D deficiency:

  • Rachite (in children): Vitamin D deficiency in children can cause rickets, a condition characterized by bone deformation.
  • Osteomulation (in adults): Vitamin D deficiency in adults can cause osteomination, a condition characterized by softening of bones.
  • Osteoporosis: Vitamin D deficiency can contribute to the development of osteoporosis, a state characterized by a decrease in bone density and an increase in the risk of fractures.
  • Increased risk of fractures: Vitamin D deficiency increases the risk of fractures, especially in the elderly.
  • Cardiovascular diseases: Vitamin D deficiency can be associated with an increased risk of developing cardiovascular diseases.
  • Autoimmune diseases: Vitamin D deficiency can increase the risk of developing some autoimmune diseases.
  • Cancer: Some studies have shown that vitamin D deficiency may be associated with an increased risk of developing certain types of cancer.
  • Depression: Vitamin D deficiency can be associated with depression and other mental disorders.

VII. Diagnosis of vitamin D deficiency: blood test for 25 (OH) d.

Diagnosis of vitamin D deficiency is carried out using a blood test for 25-hydroxyvitamin D [25(OH)D]also known as calciol. Level 25 (OH) D in the blood is the main indicator of the status of vitamin D in the body.

• Interpretation of analysis results:

  • Deficiency: Level 25 (OH) D less than 20 ng/ml (50 nmol/l).
  • Failure: Level 25 (OH) D from 20 to 29 ng/ml (50-75 nmol/l).
  • Sufficient level: Level 25 (OH) D from 30 to 100 ng/ml (75-250 nmol/l).
  • Toxicity: Level 25 (OH) D is more than 100 ng/ml (250 nmol/l).

The optimal level of vitamin D in the blood can vary depending on age, state of health and other factors. It is important to consult a doctor to interpret the results of the analysis and determine the optimal level of vitamin D for you.

VIII. Treatment of vitamin D deficiency: additives, dosage and monitoring.

Treatment of vitamin D deficiency includes intake of vitamin D additives to increase vitamin D levels to the blood to normal. The dosage and duration of treatment depend on the degree of vitamin D deficiency and the individual needs of the patient.

• Vitamin D supplements: For the treatment of vitamin D deficiency, vitamin D2 (ergocalciferol) or vitamin D3 (cholegalciferol) are usually used. Vitamin D3 is considered more effective in increasing and maintaining the level of vitamin D in the blood compared to vitamin D2.

• Dosage: The dosage of vitamin D additives depends on the degree of vitamin D deficiency and the individual needs of the patient. The doctor will determine the appropriate dosage based on the results of blood tests for 25 (OH) D. As a rule, higher doses of vitamin D are used to treat vitamin D deficiency, and lower doses are used to maintain the normal level of vitamin D.

• Supporting doses: After reaching the normal level of vitamin D in the blood, it is recommended to take supporting doses of vitamin D to prevent re -deficiency. The supporting dose is usually 600-800 IU (international units) per day for adults.

• Monitoring: During the treatment of vitamin D deficiency, it is recommended to regularly conduct a blood test for 25 (OH) D to control the level of vitamin D in the blood and adjust the dosage of additives if necessary.

It is important to note that taking vitamin D additives should be carried out under the supervision of a doctor. An overdose of vitamin D can lead to toxicity, which can cause nausea, vomiting, weakness and other symptoms.

IX. Vitamin D toxicity: symptoms, causes and treatment.

The toxicity of vitamin D, also known as hypervitaminosis D, is a condition that occurs with excessive intake of vitamin D, which leads to an increased level of vitamin D in the blood. Although the toxicity of vitamin D is rare, it can cause serious health problems.

• The causes of the toxicity of vitamin D:

  • Excessive intake of vitamin D additives: The main reason for the toxicity of vitamin D is the excessive intake of vitamin D additives, especially in high doses for a long period of time.
  • Incorrect use of additives: Sometimes people mistakenly take vitamin D additives in doses exceeding recommended.
  • Medical conditions: Some medical conditions, such as granulomatous diseases, can increase sensitivity to vitamin D and increase the risk of toxicity.

• Symptoms of vitamin D toxicity:

  • Nausea and vomiting: One of the most common symptoms of vitamin D toxicity is nausea and vomiting.
  • Weakness and fatigue: The toxicity of vitamin D can cause weakness and fatigue.
  • Loss of appetite: The toxicity of vitamin D can lead to loss of appetite.
  • Constipation: Vitamin D toxicity can cause constipation.
  • Increased thirst and frequent urination: The toxicity of vitamin D can lead to increased thirst and frequent urination.
  • Muscle weakness and bone pain: The toxicity of vitamin D can cause muscle weakness and bone pain.
  • Dehydration: The toxicity of vitamin D can lead to dehydration (dehydration).
  • Increased blood calcium (hypercalcemia): One of the main signs of vitamin D toxicity is an increased level of calcium in the blood.
  • Renal failure: In severe cases, the toxicity of vitamin D can lead to renal failure.
  • Cardiac arrhythmia: In rare cases, the toxicity of vitamin D can cause cardiac arrhythmia.

• Treatment of vitamin D toxicity:

  • Continuing taking vitamin D additives: The first step in the treatment of vitamin D toxicity is to cessation of vitamin D.

  • Reducing the level of calcium in the blood: Treatment is aimed at reducing blood calcium levels. This may include:

    • Fluid intake: An increase in fluid intake helps to reduce blood calcium.
    • Medication: The doctor can prescribe medications such as bisphosphonates and corticosteroids to reduce blood calcium.
    • Dialysis: In severe cases, dialysis may be required to remove an excess of calcium from the blood.

  • Kidney function monitoring: It is important to monitor the function of the kidneys and prevent dehydration.

The toxicity of vitamin D is a serious condition that requires immediate seeing a doctor. It is important to follow the doctor’s recommendations on the dosage of vitamin D additives and not exceed the recommended doses.

X. Recommended vitamin D consumption standards: age groups and special needs.

Recommended vitamin D consumption standards vary depending on age, health status and other factors. The Institute of Medicine (IOM) has developed the following recommended vitamin D consumption standards:

• Infants (0-12 months): 400 IU (10 mcg) per day.
• Children (1-18 years old): 600 IU (15 mcg) per day.
• Adults (19-70 years old): 600 IU (15 mcg) per day.
• Adults over 70 years old: 800 IU (20 mcg) per day.
• Pregnant and lactating women: 600 IU (15 mcg) per day.

Some people may need higher doses of vitamin D, such as:

• People with vitamin D deficiency: People with vitamin D deficiency may require higher doses of vitamin D to increase the level of vitamin D in the blood to normal.
• Oboor people: Oboor people may require higher doses of vitamin D, since vitamin D can linger in adipose tissue.
• People with dark skin: People with dark skin may require higher doses of vitamin D, since their skin produces less vitamin D under the influence of sunlight.
• People with diseases that violate vitamin D absorption: People with diseases that violate vitamin D absorption may require higher doses of vitamin D.
• Elderly people: Older people often have a reduced ability to produce vitamin D under the influence of sunlight and may need higher doses of vitamin D.

It is important to consult a doctor to determine the optimal dose of vitamin D for your individual needs.

XI. Vitamin D and disease prevention: recent studies and prospects.

Vitamin D continues to be the object of numerous studies aimed at studying its role in the prevention of various diseases. Although many results look promising, it is important to note that most of the studies are still under study, and additional studies are needed to confirm the data obtained.

• Cancer prevention: Some studies have shown that a sufficient level of vitamin D may be associated with a reduced risk of developing some types of cancer, such as colon cancer, breast cancer and prostate cancer. However, the results of the studies are contradictory, and additional studies are needed to confirm this connection.

• Prevention of cardiovascular diseases: Some studies have shown that vitamin D deficiency can be associated with an increased risk of developing cardiovascular diseases. However, the research results are also contradictory, and additional studies are necessary to determine the role of vitamin D in the prevention of cardiovascular diseases.

• Prevention of autoimmune diseases: Some studies have shown that vitamin D can play a role in the prevention of some autoimmune diseases, such as multiple sclerosis and rheumatoid arthritis. However, the research results are also contradictory, and additional studies are needed to confirm this role.

• Type 2 diabetes prevention: Some studies have shown that vitamin D can improve insulin sensitivity and reduce the risk of type 2 diabetes. However, the research results are also contradictory, and additional studies are needed to confirm this connection.

• Prevention of neurodegenerative diseases: Some studies have shown that vitamin D deficiency can be associated with an increased risk of developing neurodegenerative diseases, such as Alzheimer’s disease and Parkinson’s disease. However, the research results are also contradictory, and additional studies are needed to confirm this connection.

Despite the promising research results, it is important to note that vitamin D is not a panacea for all diseases. It is one of many factors that affect health. Maintaining a healthy lifestyle, including a balanced diet, regular physical exercises and rejection of bad habits, is the key to the prevention of diseases.

XII. Conclusion (not included, as indicated in the task)

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