Vitamin D: Why is it needed and how to get it?

Vitamin D: Why is it needed and how to get it?

I. The fundamental role of vitamin D in the human body

Vitamin D, often called “solar vitamin”, plays an incomparably important role in maintaining human health throughout life. Unlike most other vitamins, vitamin D acts as a runner, that is, the predecessor of an active hormone. Before having its biological effects, it must pass two stages of hydroxylation: first in the liver, and then in the kidneys. This process turns it into an active form, calcitriol (1,25-dihydroxyvitamin D).

A. The mechanisms of action at the cellular level:

Calcitriol binds to vitamin D (VDR) receptor, which is expressed in almost all body cells, including bones, intestines, kidneys, brain, immune system and even cancer cells. This receptor, after binding to calcitriol, forms a complex with a retinoid X-receptor (RXR). This dipmer is then associated with specific DNA sequences, known as elements of response to vitamin D (VDRA) located in the promoter areas of target genes. Binding by VDRE modulates the transcription of these genes, increasing or decreasing their expression.

This complex mechanism explains why vitamin D has such a wide effect on various physiological processes. For example, in the intestine, it stimulates the expression of genes encoding proteins necessary for the absorption of calcium, such as calbindin. In the bones, it regulates the activity of osteoblasts (cells that build bones) and osteoclasts (cells that destroy the bone), thereby maintaining bone metabolism. In the immune system, it modulates the activity of immune cells, such as T-lymphocytes and macrophages, affecting inflammatory reactions and an immune response.

B. Key functions of vitamin D:

1. Regulation of the metabolism of calcium and phosphorus: This is perhaps the most well -known function of vitamin D. It contributes to the absorption of calcium and phosphorus in the intestines, increases the reabsorption of calcium in the kidneys and mobilizes calcium from bones when it is necessary to maintain the normal level of calcium in the blood. This process is critical to maintain the health of bones and teeth, prevent rickets in children and osteomalization and osteoporosis in adults.

2. Maintaining bone health: Vitamin D plays a key role in the mineralization of bones, providing a sufficient amount of calcium and phosphorus for building and maintaining bone tissue. Vitamin D deficiency leads to a weakening of bones and increased risk of fractures, especially in older people.

3. Support for the immune system: Vitamin D modulates the immune response, supporting both innate and acquired immunity. It enhances the function of antimicrobial peptides, such as Katelicidin, which help to fight infections. It also regulates inflammatory processes, preventing excessive inflammatory reactions that can damage the tissues. Studies show that a sufficient amount of vitamin D can reduce the risk of developing autoimmune diseases, such as multiple sclerosis and rheumatoid arthritis.

4. Cell growth regulation: Vitamin D is involved in the regulation of cellular growth, differentiation and apoptosis (programmed cell death). It can inhibit the proliferation of cancer cells and contribute to their differentiation, which makes it a potential factor in the prevention and treatment of certain types of cancer.

5. Maintenance of muscle health: Vitamin D plays a role in muscle functioning, contributing to the contraction and strength of muscles. Vitamin D deficiency can lead to muscle weakness, pain and increased risk of falls, especially in the elderly.

6. Influence on the cardiovascular system: Studies show the relationship between vitamin D deficiency and an increased risk of cardiovascular diseases, such as hypertension, coronary heart disease and stroke. Vitamin D can affect blood pressure, endothelial function and inflammation, thereby maintaining the health of the cardiovascular system.

7. Regulation of blood sugar: Vitamin D can affect insulin secretion and insulin sensitivity, thereby helping to regulate blood sugar. Vitamin D deficiency is associated with an increased risk of developing type 2 diabetes.

II. Formation vitamin D: D2 and D3

There are two main forms of vitamin D: vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol).

A. Vitamin D2 (ergocalciferol):

• Origin: Vitamin D2 is synthesized by plants, mushrooms and yeast under the influence of ultraviolet (UV) radiation. Ergosterol contained in these organisms turns into vitamin D2 under the influence of UV rays.
• Sources: Enriched food, such as milk, juice and flakes, often contain vitamin D2. Some mushrooms grown under UV radiation can also be a source of vitamin D2.
• Efficiency: Studies show that vitamin D3 is usually more effective in increasing and maintaining the level of vitamin D in the blood compared to vitamin D2. Vitamin D3 is metabolized more efficiently and has a longer half -life in the body.

B. Vitamin D3 (cholecalciferol):

• Origin: Vitamin D3 is synthesized in human skin under the influence of UV rays. The 7-dehydrocholesterol contained in the skin turns into previtamin D3, which is then is metered into vitamin D3. Vitamin D3 is also contained in some products of animal origin.
• Sources: Fatty fish (salmon, tuna, mackerel), fish oil, egg yolks and liver are good sources of vitamin D3. Vitamin D3 is also available in the form of food additives.
• Efficiency: As mentioned earlier, vitamin D3 is considered more effective than vitamin D2 in increasing and maintaining the level of vitamin D in the blood. Therefore, most experts recommend vitamin D3 as a preferred form of vitamin D.

III. Getting vitamin D: sunlight, food and additives

There are three main ways to produce vitamin D: exposure to sunlight, consumption of food rich in vitamin D, and intake of food additives.

A. Vitamin D synthesis in the skin under the influence of sunlight:

• Mechanism: Under the influence of UV-in rays (with a wavelength of 290-315 nm) 7-decodrocholesterol into the skin turns into previtamin D3, which is then abundant into vitamin D3. This process is the main source of vitamin D for most people.

• Factors affecting the synthesis of vitamin D:

  • Top of year: In the winter months, when the sun is low above the horizon, UV-Rays are absorbed by the atmosphere, and the synthesis of vitamin D in the skin is significantly reduced or stopped.
  • Times of Day: The most effective synthesis of vitamin D occurs in the middle of the day, when the sun is at a zenith.
  • Latitude: People living in high latitudes (above 37 ° north latitude or below 37 ° of south latitude) are obtained less than UV rays during the year, especially in winter.
  • Cloud and air pollution: Clouds and air pollution can block UV-in-rays, reducing the synthesis of vitamin D in the skin.
  • Skin color: People with darker skin have more melanin, which absorbs uf-in rays, which reduces the synthesis of vitamin D. They need more time in the sun to produce the same amount of vitamin D as people with light skin.
  • Age: With age, the ability of the skin to synthesize vitamin D decreases.
  • Use of sunscreen: Sunscous cream blocks uf-in rays and can significantly reduce the synthesis of vitamin D in the skin. However, it is important to use sunscreen to protect against skin cancer.

• Recommendations for the sun stay: There are no single recommendations for the time of stay in the Sun, as it depends on many factors mentioned above. In general, for people with fair skin, 10-15 minutes of stay in the sun in the middle of the day several times a week are enough to get a sufficient amount of vitamin D. People with darker skin may take more time. It is important to remember the risk of sunburn and take precautions in order to protect the skin from excessive exposure to the sun.

B. Vitamin D in food:

• Natural sources of vitamin D: A limited amount of food contains vitamin D in a natural form. These include:

  • Fat fish: Salmon, tuna, mackerel and herring are good sources of vitamin D3. Wild salmon, as a rule, contains more vitamin D than grown salmon.
  • Fish oil: Fish oil, especially the fat fat, is a rich source of vitamin D3.
  • Egg yolks: Egg yolks contain a small amount of vitamin D3. The amount of vitamin D in egg yolks depends on the diet of chickens.
  • Beef liver: Beef liver also contains a small amount of vitamin D3.
  • Mushrooms: Some mushrooms, especially those that are exposed to UV radiation, contain vitamin D2.

• Enriched food: Many foods are enriched with vitamin D to increase the consumption of this vitamin among the population. These include:

  • Milk: Milk is often enriched with vitamin D, usually vitamin D3.
  • Juice: Orange juice and other juices can also be enriched with vitamin D.
  • Breakfast flakes: Many breakfast flakes are enriched with vitamin D.
  • Yogurt: Some types of yogurt are also enriched with vitamin D.

• Problems with obtaining a sufficient amount of vitamin D only from food: Even when eating foods rich in vitamin D, and enriched food, it is difficult to get a sufficient amount of vitamin D only from food. This is especially true for people who do not use animal products (vegetarians and vegans) or have limited consumption of fatty fish.

C. Vitamin D food supplements:

• Types of vitamin D additives: Vitamin D is available in the form of various food additives, including vitamin D2 (ergocalciferol) and vitamin D3 (cholegalciferol). As mentioned earlier, vitamin D3 is considered more effective than vitamin D2.
• Dosage: The recommended daily dose of vitamin D depends on the age, state of health and level of vitamin D in the blood. It is usually recommended 600 IU (international units) per day for adults, but some people may need a higher dose, especially with vitamin D deficiency. It is important to consult a doctor to determine the optimal dose of vitamin D for your individual needs.
• Safety: Vitamin D is generally safe when taking recommended doses. However, taking very high doses of vitamin D (more than 4000 IU per day) for a long time can lead to toxicity, which manifests itself in the form of hypercalcemia (an increased level of calcium in the blood). Symptoms of hypercalcemia can include nausea, vomiting, weakness, frequent urination and kidney problems.

IV. Vitamin D deficiency: causes, symptoms and consequences

Vitamin D deficiency is a common problem around the world. According to estimates, more than 1 billion people around the world have a low level of vitamin D in the blood.

A. The causes of vitamin D deficiency:

• Insufficient stay in the sun: This is perhaps the most common reason for the deficiency of vitamin D. People who spend most of the time in the room, wear closed clothes or live in regions with limited sunlight, are at risk of vitamin D.
• Insufficient consumption of vitamin D with food: As mentioned earlier, it is difficult to get a sufficient amount of vitamin D only from food. People who do not use animal products or have limited consumption of fatty fish are at risk of vitamin D.
• Diseases that violate vitamin D absorption: Some diseases, such as Crohn’s disease, celiac disease and cystic fibrosis, may disrupt vitamin D absorption in the intestines.
• Liver and kidney diseases: Diseases of the liver and kidneys can disrupt the transformation of vitamin D into its active form, calcitriol.
• Obesity: Vitamin D is a fat -soluble vitamin, and in people with obesity vitamin D can “sequest” in adipose tissue, which reduces its accessibility for the rest of the body.
• Some drugs: Some drugs, such as glucocorticoids and anticonvulsants, can affect vitamin D.’s metabolism.

B. Symptoms of vitamin D:

Symptoms of vitamin D deficiency can be non -specific and often go unnoticed. These include:

• Fatigue and weakness: Vitamin D deficiency can cause fatigue and weakness, even after a sufficient rest.
• Bone pain and muscles: Vitamin D deficiency can lead to pain in bones and muscles, as well as muscle weakness.
• Frequent infections: Vitamin D deficiency can weaken the immune system and increase susceptibility to infections.
• Depression: Studies show the relationship between vitamin D deficiency and depression.
• Slow healing of wounds: Vitamin D deficiency can slow down the healing of wounds.
• Hair loss: In some cases, vitamin D deficiency can lead to hair loss.

C. The consequences of the deficiency of vitamin D:

A long deficiency of vitamin D can lead to serious health consequences, especially in children and older people.

• Rachite (in children): Rickets are a disease characterized by softening and deformation of bones in children. This is due to a lack of calcium and phosphorus caused by a deficiency of vitamin D.
• Osteomulation (in adults): Osteomulation is a disease characterized by softening of bones in adults. This also occurs due to a lack of calcium and phosphorus caused by vitamin D. deficiency.
• Osteoporosis: Vitamin D deficiency can contribute to the development of osteoporosis, a disease characterized by a decrease in bone density and an increased risk of fractures.
• Increased risk of fractures: Vitamin D deficiency increases the risk of bone fractures, especially in the elderly.
• Increased risk of falls: Vitamin D deficiency can lead to muscle weakness and increased risk of falls, especially in older people.
• Increased risk of cardiovascular disease: Studies show the relationship between vitamin D deficiency and an increased risk of cardiovascular diseases, such as hypertension, coronary heart disease and stroke.
• Increased risk of autoimmune diseases: Vitamin D deficiency is associated with an increased risk of developing autoimmune diseases, such as multiple sclerosis and rheumatoid arthritis.
• Increased risk of some types of cancer: Studies show the relationship between vitamin D deficiency and the increased risk of some types of cancer, such as colon cancer, breast cancer and prostate cancer.
• Increased risk of type 2 diabetes: Vitamin D deficiency is associated with an increased risk of developing type 2 diabetes.

V. Diagnosis of vitamin D deficiency

Diagnosis of vitamin D deficiency is carried out by measuring the level of 25-hydroxyvitamin D [25(OH)D] In the blood. This is the main form of vitamin D, circulating in the blood, and its level is a reliable indicator of vitamin D status in the body.

• Normal level: The optimal level 25 (OH) D in the blood is 30-50 ng/ml (75-125 nmol/L).
• Insufficient level: Level 25 (OH) D in the blood from 20 to 29 ng/ml (50-72.5 nmol/L) is considered insufficient.
• Deficiency: Level 25 (OH) D in the blood below 20 ng/ml (50 nmol/l) is considered a deficiency.

It is important to consult a doctor for a blood test and interpret the results. The doctor can also prescribe additional examinations to exclude other diseases that can cause such symptoms.

VI. Risk groups by vitamin D deficiency

Some groups of people are at risk of vitamin D deficiency. These include:

• Elderly people: With age, the ability of the skin to synthesize vitamin D decreases. Older people also often spend more time in the room and have reduced consumption of vitamin D with food.
• People with dark skin: People with darker skin have more melanin, which absorbs uf-in rays, which reduces the synthesis of vitamin D.
• Oboor people: Vitamin D is a fat -soluble vitamin, and in people with obesity vitamin D can “sequest” in adipose tissue, which reduces its accessibility for the rest of the body.
• People living in high latitudes: People living in high latitudes (above 37 ° north latitude or below 37 ° of south latitude) are obtained less than UV rays during the year, especially in winter.
• People suffering from diseases that violate the absorption of vitamin D: Some diseases, such as Crohn’s disease, celiac disease and cystic fibrosis, may disrupt vitamin D absorption in the intestines.
• People taking some medicines: Some drugs, such as glucocorticoids and anticonvulsants, can affect vitamin D.’s metabolism.
• Pregnant and lactating women: Pregnant and lactating women need more vitamin D to maintain the health of both the mother and the child.
• Babs on breastfeeding: Breast milk may not contain a sufficient amount of vitamin D, therefore, infants who are on breast feeding are often recommended to give vitamin D.
• Vegetarians and vegans: Vegetarians and vegans may not receive enough vitamin D from food, since the main sources of vitamin D are animal products.

VII. Treatment of vitamin D deficiency

Treatment of vitamin D deficiency includes an increase in vitamin D levels in the blood to the normal range. This is usually achieved by taking vitamin D.

• Dosage: The dosage of vitamin D additives depends on the degree of vitamin D deficiency. Usually higher doses are prescribed (for example, 50,000 IU per week) for several weeks to quickly increase the level of vitamin D in the blood, and then a maintenance dose (for example, 1000-2000 IU per day) to maintain a normal level of vitamin D. It is important to consult a doctor to determine the optimal dose of vitamin D for your individual needs.
• Form Supplements: Vitamin D3 (cholecalciferol) is a preferred form of additive of vitamin D, since it is more effective than vitamin D2 (ergocalciferol).
• Monitoring: After the intake of the additives of vitamin D, it is important to regularly check the level 25 (OH) D in the blood to make sure that the level of vitamin D is in the normal range.

In addition to taking vitamin D additives, it is also important to increase the consumption of foods rich in vitamin D, and spend more time in the sun (in compliance with precautions for protection against sunburn).

VIII. Prevention of vitamin D deficiency

Prevention of vitamin D deficiency includes measures to maintain a sufficient level of vitamin D in the blood.

• Sun stay: Regular stay in the sun (10-15 minutes in the middle of the day several times a week) can help maintain a sufficient level of vitamin D in the skin. However, it is important to remember the risk of sunburn and take precautions in order to protect the skin from excessive exposure to the sun.
• The use of foods rich in vitamin D: Include foods rich in vitamin D in your diet, such as fatty fish, fish oil, egg yolks and enriched foods.
• Reception of vitamin D additives: If you do not get enough vitamin D from sunlight and food, consider taking vitamin D additives. Consult a doctor to determine the optimal dose of vitamin D for your individual needs.
• Regular blood tests: Regularly check the level 25 (OH) D in the blood, especially if you are at risk by the deficiency of vitamin D.

IX. Vitamin D and Covid-19

In recent years, interest in the role of vitamin D has increased in the prevention and treatment of Covid-19. Some studies have shown the relationship between the low level of vitamin D and the increased risk of infection Covid-19, a more severe course of the disease and an increased risk of death.

• Action mechanisms: Vitamin D can have a protective effect against the COVID-19 due to several mechanisms, including:

  • Strengthening the immune system: Vitamin D modulates the immune response, supporting both innate and acquired immunity.
  • Reduced inflammation: Vitamin D regulates inflammatory processes, preventing excessive inflammatory reactions that can damage the tissues.
  • Strengthening antimicrobial peptides: Vitamin D enhances the function of antimicrobial peptides, such as Katelicidin, which help to fight infections.

• Research results: Although some studies have shown the relationship between the low level of vitamin D and the increased risk of the COVID-19, the results of other studies were contradictory. Additional studies are needed to confirm this connection and determine the optimal dose of vitamin D for the prevention and treatment of COVID-19.

• Recommendations: Currently, most medical organizations recommend maintaining a sufficient level of vitamin D in the blood for general health, but do not recommend using vitamin D as the only means of prevention or treatment of Covid-19. It is important to follow the recommendations for vaccination and other measures of the COVID-19 prevention.

X. Conclusion

Vitamin D plays an important role in maintaining human health throughout life. It is necessary to regulate the metabolism of calcium and phosphorus, maintain bone health, support the immune system, regulate cell growth, maintain muscle health and effect on the cardiovascular system and blood sugar.

Vitamin D deficiency is a common problem that can lead to serious health consequences. It is important to take measures to maintain a sufficient level of vitamin D in the blood, including exposure to the sun, the use of foods rich in vitamin D, and taking vitamin D additives, if necessary.

Regularly check the level 25 (OH) D in the blood and consult a doctor to determine the optimal dose of vitamin D for your individual needs.