دکتر صابر سادات امینی فوق تخصص بیماریهای غدد و متابولیسم و متخصص داخلی از دانشگاه علوم پزشکی شهید بهشتی – عضو هیات علمی دانشگاه ادرس مطب : تهران ، خیابان شریعتی،بالاتر ازایستگاه مترو قلهک،کوچه سجاد، پلاک ۶۶، طبقه پنجم،واحد ۴ تلفن مطب ۰۹۱۹۸۰۴۸۷۸۲

📌 ویتامین D: ویتامینی حیاتی برای سلامت استخوان‌ها، سیستم ایمنی – راهنمای کامل ویتامین د

✨ مقدمه — ویتامین D چیست؟

ویتامین D (یا کلسی‌فرول) یک ویتامین محلول در چربی است که نقش بسیار مهمی در سلامت بدن ایفا می‌کند. برخلاف بسیاری از ویتامین‌ها، بدن انسان می‌تواند بخش قابل توجهی از نیاز خود را از طریق سنتز پوستی با کمک نور خورشید تأمین کند؛ به همین دلیل به آن «ویتامین آفتاب» نیز گفته می‌شود.

این ویتامین هم از طریق برخی مواد غذایی قابل دریافت است و هم به‌صورت مکمل‌های خوراکی در دسترس قرار دارد. Vitamin D has two main forms:
D2 (ergocalciferol) and D3 (cholecalciferol) which type D3 is more effective in increasing and maintaining the proper level of vitamin D in the blood.

🧠 The role of vitamin D in the body

Vitamin D has many important functions in the body, including the following:

✔️ 1. Bone and teeth health

This vitamin helps absorb calcium and phosphorus from the digestive system and is necessary for the formation and maintenance of healthy bones. Its deficiency can lead to bone softening in adults and rickets in children.

✔️ 2. Strengthening the immune system

Vitamin D plays an important role in regulating the body's immune response and can be effective in reducing the risk of certain infections.

✔️ 3. Muscle function

Adequate levels of vitamin D can reduce muscle weakness and reduce the risk of falls, especially in the elderly.

✔️ 4. Possible role in other diseases

Some studies suggest that adequate levels of vitamin D may be associated with reduced risk of some cancers, improved cardiovascular health, and improved mood, although some of these effects still need more research.

🍽 Sources of vitamin D — what should we eat?

🌞 sunlight

Exposure to sunlight is the most natural way to produce vitamin D in the body. Usually 10 to 30 minutes, several days a week is enough for most people, although this time depends on skin color, season and geographical location.

🍣 food sources

Some food sources containing vitamin D are:

• fatty fish such as salmon and sardines

• Egg Yolk

• Mushrooms exposed to ultraviolet light

• Vitamin D-fortified foods such as some dairy products and breakfast cereals

📉 Vitamin D deficiency — causes, symptoms and consequences

❗ Why does vitamin D deficiency occur?

Common causes of shortages include:

• Living in closed environments and receiving insufficient sunlight

• High use of sunscreen or full skin coverage

• diet lacking sufficient sources of vitamin D

• Intestinal fat absorption disorders (such as celiac disease or Crohn's disease)

⚠️ possible symptoms of vitamin D deficiency

• Unexplained fatigue and weakness

• bone or muscle pain

• Frequent breaks

• Decreased immunity and frequent infections

📊 Long-term consequences of scarcity

Severe and long-term vitamin D deficiency can lead to:

• osteoporosis

• osteomalacia

• Increased risk of infections and some metabolic problems

💊 recommended doses and how to treat deficiency

📌 normal consumption

For most adults, a daily intake of 600 to 800 international units (IU) is recommended, but in some individuals, such as the elderly or those with proven deficiencies, a higher dose may be needed.

Treatment of vitamin D deficiency

If a deficiency is diagnosed, the doctor may prescribe higher therapeutic doses for a certain period of time and after correcting the deficiency, recommend taking maintenance doses. Treatment usually includes vitamin D3 supplements, increased exposure to sunlight, and dietary modification.

✨ Note: Excessive consumption of vitamin D can be dangerous and cause an increase in blood calcium, kidney stones and heart problems; Therefore the use of supplements must be done under the supervision of a doctor.

❓ Frequently Asked Questions (FAQ)

1. What is vitamin D and why do we need it?

Vitamin D is a fat-soluble vitamin that helps absorb calcium and phosphorus and is essential for bone health, immune system and muscle function.

2. Who are more susceptible to vitamin D deficiency?

People who spend a lot of time indoors, the elderly, people with dark skin and those with malabsorption disorders are more prone to vitamin D deficiency.

3. Do I need to take vitamin D supplements?

If you are at risk of deficiency or if a blood test shows low levels of vitamin D, taking a supplement under the supervision of a doctor can be useful and necessary.

4. How much sunlight is enough to provide vitamin D?

For many people, 10 to 30 minutes of exposure to sunlight, several days a week is enough; Of course, this period can be different depending on individual circumstances.

5. Is vitamin D only available through sunlight?

No. Although sunlight is the most important natural source of vitamin D, fortified foods, fatty fish, egg yolks, and supplements are also good sources.

6. How is vitamin D deficiency diagnosed?

The only accurate way is blood test and measure the level of 25(OH) vitamin D. Symptoms alone are not enough for diagnosis.

7. What is the normal number of vitamin D in a blood test?

• Less than 20 ng/ml: deficiency

• 20 to 30: insufficient

• 30 to 50: suitable

• Above 100: risk of poisoning

8. Should everyone be tested for vitamin D?

No, but it is recommended in high-risk people such as patients with glands, diabetes, thyroid, pregnant women, elderly and obese people.

9. Does vitamin D deficiency cause bone and joint pain?

Yes, vague muscle and bone pain is one of the most common symptoms of vitamin D deficiency.

10. Does vitamin D deficiency cause fatigue and lethargy?

Yes, many patients experience chronic fatigue and low energy.

🧠 special questions for endocrine patients

11. Is vitamin D deficiency more common in endocrine patients?

Yes, especially in patients with thyroid disorders, diabetes and polycystic ovary syndrome (PCOS).

12. Does vitamin D affect the function of hormones?

Vitamin D has a regulatory role in the hormonal system and its receptors are present in many glandular tissues.

13. Can vitamin D deficiency cause osteoporosis?

Yes, long-term vitamin D deficiency is one of the important factors of osteoporosis and fractures.

🩸 special questions for diabetic patients

14. Are diabetic patients more prone to vitamin D deficiency?

Yes, vitamin D deficiency is more common in type 1 and type 2 diabetes patients.

15. Does vitamin D have an effect on blood sugar?

Some studies show that vitamin D can help improve insulin sensitivity, but it is not a cure for diabetes.

16. Is it safe to take vitamin D for diabetic patients?

In the right dose and under the supervision of a doctor, yes. Arbitrary consumption of high doses is not recommended.

17. Does vitamin D prevent the complications of diabetes such as leg pain?

Not directly, but its deficiency can aggravate muscle pain and weakness.

🦋 special questions for thyroid patients

18. Is vitamin D deficiency common in hypothyroidism?

Yes, especially in autoimmune thyroid diseases like Hashimoto.

19. Does vitamin D have an effect on thyroid autoimmune diseases?

Vitamin D may play a role in immune regulation, but is not a substitute for primary thyroid therapy.

20. Does taking vitamin D interfere with levothyroxine?

No, but it is better to be consumed at a different time of the day.

21. Should thyroid patients check their vitamin D levels regularly?

In many cases yes, especially if there are bone or fatigue symptoms.

🤰 Special questions for pregnant women

22. Is vitamin D deficiency dangerous in pregnancy?

Yes, its deficiency can have a negative effect on the health of the mother and the development of the bones of the fetus.

23. Should all pregnant women take vitamin D?

24. What are the complications of vitamin D deficiency in pregnancy?

25. Is excessive consumption of vitamin D dangerous during pregnancy?

Yes, arbitrary consumption of high doses can increase blood calcium.

💊 questions about supplement use

26. What is the best type of vitamin D supplement?

Vitamin D3 (cholecalciferol) is more effective than D2.

27. Is it better to use daily or weekly?

Both methods are effective and the choice depends on the doctor's opinion and the degree of deficiency.

28. When is the best time to take vitamin D?

Together with meal containing fat for better absorption.

29. Is vitamin D ampoule better than pill?

No, it is only used in special circumstances and severe shortages.

30. How often should vitamin D levels be checked?

Usually every 3 to 6 months in treated or high-risk patients.

31. Is excessive consumption of vitamin D dangerous?

Yes, it can cause poisoning, kidney stones and kidney damage.

32. Does vitamin D cause obesity or thinness?

No, but a deficiency may be associated with being overweight.

33. Do children and teenagers also need vitamin D?

Yes, it is necessary for the growth of bones and prevention of rickets.

34. Does vitamin D strengthen the immune system?

Yes, it plays an important role in regulating the body's immune response.

35. For whom is vitamin D pill 1000 units per day suitable?

1000 IU tablets are usually used to prevent deficiency and maintain normal levels of vitamin D in healthy people or those with mild deficiency.

36. Is daily intake of vitamin D better than weekly?

At the level of prevention, the daily intake of a low dose (such as 800 to 1000 units) is stable and safe; But in deficiencies, higher weekly doses are more useful.

37. Vitamin D tablets of 50,000 units are prescribed for which people?

A dose of 50,000 units is usually prescribed for treatment of moderate to severe vitamin D deficiency and under medical supervision.

38. How often is the 50,000 unit pill taken once?

In most cases one number per week for 6 to 8 weeks, then treatment is continued with a maintenance dose.

39. Is it possible to take 50,000 tablets arbitrarily?

No, arbitrary consumption of this dose can cause vitamin D poisoning and must be prescribed by a doctor.

40. What should be done after the course of 50,000 tablets?

Usually, after the deficiency is corrected, the treatment is continued with a maintenance dose of 800 to 1000 units daily or monthly.

41. Is 1000 unit tablets enough to treat severe deficiency?

No, in severe deficiency it is usually not enough and higher therapeutic doses are needed.

42. What is the main difference between 1,000 units and 50,000 units tablets?

The main difference is in the target of treatment:

• 1000 units → prevention and maintenance

• 50,000 Units → Proven Deficiency Treatment

43. Does weekly consumption cause better absorption?

Overall absorption is not much different, but weekly dosing is useful for better patient adherence in short-term treatment.

44. Can diabetic patients take pills of 50,000 units?

45. Are thyroid patients allowed to take high doses?

Yes, if needed; But it should take it separately from levothyroxine.

46. Can pregnant women take pills of 50,000 units?

In pregnancy, lower and controlled daily or weekly doses are usually preferred and only with the doctor's opinion.

47. Is the monthly consumption of 50,000 units also allowed?

In some people it is used as a monthly maintenance dose, not a treatment for severe deficiency.

48. When is the best time to take high dose pills?

Together with main meal containing fat for better absorption.

49. What should be done if a weekly dose of 50,000 units is forgotten?

Take as soon as you remember, but Dosing twice in one day is not recommended.

50. Is there anything wrong with taking high-dose calcium and vitamin D at the same time?

Useful in most cases, but should be used with caution in patients with kidney stones or high calcium.

51. What are the symptoms of excessive consumption of vitamin D?

Nausea, constipation, extreme thirst, frequent urination, kidney pain and increased blood calcium.

52. How long after the start of treatment should the test be repeated?

Usually after 8 to 12 weeks to assess treatment response.

53. Is it possible to take daily and weekly pills at the same time?

54. Is the dose of vitamin D the same for everyone?

No, it depends on age, weight, underlying diseases, pregnancy and level of deficiency.

55. With whom is the final decision to choose the dosage and type of use?

Always consult a physician, especially an endocrinologist based on blood tests.

56. What kind of doctor should we consult to treat vitamin D deficiency?

To investigate and treat vitamin D deficiency, an Endocrinologist and Metabolist is the best choice. Vitamin D plays an important role in the regulation of hormones, calcium metabolism, bone health and gland function, and its correct treatment requires careful hormonal and laboratory evaluation.

In more complex cases like:

• Severe and treatment-resistant deficiency

• Combination with diabetes, thyroid diseases, severe osteoporosis

• Disorders of calcium and phosphorus metabolism

• or rare endocrine diseases

It may be necessary to refer to endocrine and metabolism specialist.