Dr. Kazi Kismat Ara (M22 batch, Mymensingh Medical College)

[Sunshine Vitamin] : Important information about Vitamin D

INTRODUCTION:

Vit. D is called the Sunshine Vitamin, as 70% of this vitamin required by the body is obtained from sunlight. Sun's UVB rays (ultra violet rays) come in contact with the skin to produce this vitamin. According to WHO (World Health Organization), currently more than 100 million people in the world are suffering from lack of essential Vit D. This pandemic of hypovitaminosis D can mainly be attributed to reduced outdoor activities & air pollution factors that reduce exposure to sunlight, which is required for ultraviolet-B (UVB)-induced vitamin D production in the skin. 

 FUNCTIONALITY:

Previously, the function of this vitamin was thought to be mainly on bone health & its structure. After the Covid 19 epidemic, the contribution of this vitamin to the proper functioning of the body's immune system is undeniable. Many of us may not know that VitD is a pro-hormone. That is, it works like a hormone. The UVB ray of the sun is the main source of Vit D (70% - 80%). There is a chemical precursor called 7Dehydoxycholesterol under the skin. When sunlight hits the skin, it reacts with it to produce Vit D. After going to the liver and kidneys, it is converted into a type of hormone called calcitrol. It absorbs calcium from the intestine and reaches the whole body. This calcitrol is the original form of vitamin D.

Vit D is a fat-soluble vitamin. In other words, we need good fats in our body to absorb it.         

HOW TO GET VIT D FROM SUNLIGHT? 

When the sun is bright, VitD reaches the earth. When we go out into the light and see that our shadow is smaller than us, that light has more VitD. That is, if we sit in the sunlight with 20 percent of our body exposed from 10 am to 3 pm, we will get 70%-80% of the required vitamin-D. Interestingly, there is no chance of overdosing on VitD from sunlight, only what is needed will be absorbed. However, to avoid the risk of skin cancer, we should not stay in strong sunlight for a long time.

OTHER SOURCES OF VITAMIN D:

Two other sources of Vit-D are food and supplement.  Among the food, there are sea fish Salmon, Sardin, Harry. Among the local fish, Hilsa fish is especially the part of stomach. Also, sour yogurt, milk, eggs, butter contain Vit D in fatty foods. Among the vegetable sources, mushrooms contain Vit-D. The meat, milk, and eggs of animals that graze in the sunlight have higher amounts of Vit-D. Another source is supplement. D2 and D3 are available in pharmacies in two forms. Vit D3 is relatively more effective. However, it is important to consult a doctor before taking it. 

BODY REQUIREMENT OF VIT D:

    How much vitamin is needed depends on the age. Adults need 600 IU of Vit D per day. Those over 71 years of age need 800 IU of Vit D per day. Excessive intake of Vit-D can have side effects. It increases the level of calcium in our body, which causes damage to blood vessels, heart and kidneys. American institute of medicine recommends maximum intake of 4000 IU of Vit-D per day. More than this can cause toxicity.

CAN EVERYONE GET VIT D FROM SUNLIGHT?

 People with fair or lighter skin can get enough Vit-D from sunlight every 20-25 minutes. On the other hand, those with darker skin or brown skin like us have more melanin pigment, it prevents the sun's UVB rays from entering the body. Therefore, we need to spend more time (40 minutes) in the sunlight to get enough VitD.  Moreover, the ability to synthesize Vit D also decreases with age. People confined indoors and those whose body is covered by clothes and sunlight cannot reach the body are at higher risk of Vit D deficiency. Some diseases reduce the absorption capacity of VitD such as Ulcerative colitis, Celiac disease, Chron's disease. These patients are at risk of Vit D deficiency.

Obese people and those who have undergone gastric bypass surgery are at greater risk of VitD deficiency. Dept. of health & social care in England advised these groups of people to take Vit.D supplement. But in this case, we must check the amount of VitD in the blood and take the supplement accordingly.

EFFECT OF VIT D: DEFICIENCY:

Vit D or Calcitrol helps in the absorption of calcium from our intestines. Calcium is essential for bone growth and stability. If it is deficient, the bones become brittle (osteoporosis) at one stage. It is essential for maintaining healthy bones, teeth and muscles. VitD deficiency in children causes a bone deformity called Ricketts. Bones become soft (osteomalacia) in the elderly. Some studies say that, Vit.DA contributes to reducing the risk of corona virus.

HOW DOES VIT.D WORK ON THE BODY'S IMMUNITY SYSTEM?

Basically, T helper cell and T regulatory cell cannot work properly due to lack of it. These two cells play a major role in immune response. Besides, Macrophages, the main power of strong immunity (eating bacteria, virus) cannot work properly due to lack of VitD.  As a result, the risk of infection by viruses and bacteria increases to a large extent.

VitD inhibits the cytokine system, it causes the immune system to malfunction, and disables the body's major organs in what is known as a cytokine storm. Cytokine storm is the main cause of death in Covid19. Besides, some people have died due to blood clots. Antithrombic property of Vit D reduces the risk of blood clots.

CLINICAL FEATURES OF VIT. D DEFICIENCY:

[a]. Fatigue due to little effort, [b] Muscle pain - Unbearable pain in waist, neck and back, [c]. Osteoporosis – Bones become brittle as well as deforming the bone structure., [d]. anxiety disorder - Panic for very little reason, [e] Depression - Brain cannot function properly due to lack of Vit D, [f] Impaired wound healing – wound drying is delayed, [g] Excessive hair fall – Vit D stimulates hair follicle. [h] Excess weight gain can be due to lack of this vitamin.

VITD TOXICITY: 

Vit D supplement can cause hypercalcemia (high blood calcium level) due to long-term excess intake - 

Its symptoms are –Muscle weakness, excessive headache, nausea, bone pain, loss of appetite. Long-term symptoms can include constipation, kidney stones, and heart abnormalities.

Therefore, the maximum daily dose should not exceed 4000 IU. It is best to check the amount of VitD in the blood depending on the age and physical condition and take vitamin supplement as per the advice of the doctor.

CONCLUSION:

 A comprehensive strategy & national dietary guideline needed to improve and control the health consequences of vitamin D deficiency. This would include the creation of public awareness, refrain in sunscreen usage, exposure to sunlight, regular exercise, food fortification, food supplement and medication supplementation with vitamin D. We have to consider the availability and affordability of food supplement of vitamin D. Unfortunately, the vitamin D enriched food supplements are expensive. Therefore, the plenty of natural sunlight we can use it in proper way.

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