THE DIRE NEED FOR VITAMIN D

Warm Greetings!

In the midst of the Coronavirus pandemic that has affected the health of people gravely, I would like to bring your attention to a probable treatment method that would strengthen our immune system and indirectly help us fight this deadly virus.

Yes, I did mention in my last blog that viruses cannot be killed but we can definitely take steps to build our immunity towards tolerating these pathogenic strains. In this article, I would discuss one of the most potent and essential vitamins that we have free access to – Vitamin D.

Even though we have a significant prevalence of sunshine, especially in Mumbai, more than half of the population is Vitamin D deficient or insufficient. How can this be even remotely possible? The reason behind this is that there is more to Vitamin D synthesis and absorption that we all fail to consider.

Vitamin D, also known as Cholecalciferol, is more of a steroid hormone for our bodies. The body can either synthesize it by utilizing the rays of the sun or it can absorb it from our dietary food sources.

SYNTHESIS OF VITAMIN D FROM THE SUN:

There are two types of Vitamin D – Vitamin D₂ (Ergocalciferol) and Vitamin D₃ (Cholecalciferol). Both of these forms are inactive and need activation by the Liver and the Kidneys respectively. Vitamin D₂ is synthesized in certain yeast and fungi, whereas Vitamin D₃ is synthesized in animals like fish, humans etc.

Whenever we expose ourselves to the Sunlight, the Ultraviolet (UV)-B radiation that falls in the 290-315 nm of wavelength, undergoes a phytochemical reaction with 7-dehydrocholesterol on our skin. The UV-B from the Sun reacts with cholesterol/fat on our skin to synthesize a stable yet inactive Vitamin D₃ within our bodies.

This inactive vitamin D₃ is attached to a Vitamin D binding protein (DBP) and sent to the Liver for its first stage activation. In the Liver, a certain enzyme called as Vitamin D 25- hydroxylase adds a hydroxyl group (OH) to the inactive Vitamin D₃ to form 25 (OH) Vitamin D or 25(OH)D. 25(OH)D in the Liver is used as a biomarker for checking Vitamin D status in humans.

25(OH)D is further hydroxylated in the Kidneys by the enzyme 1-α-hydroxylase to synthesize the active form of Vitamin D known as 1,25 Dihydroxy Vitamin D or 1,25(OH)₂D.

This active form of Vitamin D then binds to specific receptors known as Vitamin D receptor or VDR. This complex then further binds to Retinoid-X-receptor to form a heterodimer (A dimer of two different proteins)

I know this seems highly technical but that’s how the body works. In order to isolate the vital information, we have the following factors that affect levels of Vitamin D;

• Vitamin D synthesis from UV-B radiation from the Sun requires the presence of Cholesterol on our skin. A low fat diet would indirectly affect the cholesterol levels on the surface of the skin and prevent Vitamin D synthesis.
• Dietary Vitamin D is a fat soluble vitamin which can be absorbed only in presence of Bile. Bile is a fat cleaving fluid which is produced by the gut microbes, Liver and stored in the Gall-bladder. A deficiency of Bile may lead to insufficient absorption of Vitamin D from the diet. 
• Retinoid-X-receptor (RXR) is closely associated with Vitamin A and hence, Vitamin A levels affect Vitamin D levels. 
• In order to activate Vitamin D, one must possess a healthy and functional Liver as well as kidneys. Any hindrance to the normal functioning of these organs would lead to less Vitamin D activation. 

FUNCTIONS OF VITAMIN D:

After going through the synthesis of Vitamin D, let us understand the following functions of Vitamin D;

• Mineralization of the Bones: Vitamin D allows the absorption of Calcium (x20 times) and Phosphate in the small intestine from dietary sources. In order to drive this calcium into the bones and prevent any calcium accumulation in soft tissues or arteries, Vitamin D works with Vitamin K₂ to balance out the excess calcium in the blood. 
• Immune Modulator: Apart from bone strengthening, Vitamin D plays an extremely vital role in controlling our immune cells. All our immune cells like B-cells, T-cells, dendritic cells, and macrophages which act as body’s defence barrier against foreign pathogens are greatly influenced by Vitamin D mainly as these cells express the Vitamin D receptor.
  When a foreign antigen (microbe/virus/fungi) enters our body, the VDR-1,25(OH)₂D-RXR complex binds to certain regions on our DNA (Genetic material) and expresses certain protein peptides like ‘Cathelocidin’ and ‘Beta-defensin 4’ which have the ability to kill the foreign body. Thus Vitamin D helps us protect against various pathogenic strains by modifying our immune cells. 
• Anti-inflammatory Nature: Our immune system creates inflammation during the process of killing a pathogen. Inflammation is basically a hypersensitive reaction caused by influx of immune cells like White blood cells and increased blood flow to the area. This inflammation is taken care by Vitamin D which is known to have an anti-inflammatory nature. Thus, Vitamin D is known to improve the symptoms of Auto-immune diseases like Rheumatoid Arthritis, Diabetes Mellitus, Multiple Sclerosis etc.Because of such properties, Vitamin D also helps to improve high blood pressure and Asthma symptoms.
• Bone Cell Development: As vitamin D helps in calcium absorption, it also affects the development of Osteoclasts within our bones. Osteoclasts are basically cells that utilise the calcium and reshape bones. Thus a deficiency of Vitamin D would lead to poor bone development and a poor posture of the skeletal framework.
• Anti-Viral Nature: Since Vitamin D has a strong control over the immune system, there have been studies of viruses involved in blocking the Vitamin D receptor. This allows the virus to override our immune barrier and hijack our cellular machinery.
• Mood and Sleep Booster: Vitamin D decreases the nervous tension and helps one calm down.
  
  
  In addition to all these functions, Vitamin D receptors are widely present in Intestine, pancreatic beta cells, tubular kidney cells, bronchial epithelial cells, reproductive cells as well as breast tissue, thus portraying wide applications to various organs.
  
  
  
  
  
  
  REQUIREMENTS & SOURCES OF VITAMIN D:
  The recommended dietary allowance (RDA) of Vitamin D is in the range of 400-800 IU (International Units). Before we go any further, let’s just understand the relationship between IUs and grams.
  
  
  1 IU of Vitamin D = 0.025 mcg (micrograms)
  
  
  800 IU of Vitamin D = 20 mcg
  
  
  The RDAs for Vitamin D are selected based on preventing a disorder from its deficiency like Rickets. Rickets is a condition of Vitamin D deficiency whereby the bones become fragile and start bending.
  
  
  In order to maintain a healthy body, one must expose to much more Vitamin D. For example, every 10 minutes spent under the sun at midday would provide 10,000 IUs of Vitamin D. For those who think such a number is outrageous, let’s convert it into micrograms.
  10,000 IU of Vitamin D = 250 mcg
  
  
  Thus the amount of Vitamin D obtained from the sun is really inexpensive but the positive effects are innumerable.
  
  But what about food sources? Well to be really honest, you won’t even get close to RDAs with dietary sources except Cod Liver Oil which has approximately 1360 IU of a single table spoon. 
  
  
  Other food sources that people consume for Vitamin D include Mushrooms, egg yolk, oysters, salmon, sardines, tuna etc. but hardly absorb any Vitamin D.
  
  In order to obtain maximum benefits of Vitamin D, one must expose 70% of the body surface under the midday sunlight for about 20-30 minutes. One must carefully monitor non-burning skin exposure to the sunlight as skin damage would lead to more health problems. 
  
  
  MYTH WRECKER, FACT CHECKER: (Myths are underlined, facts are italic)
  
  
• Vitamin D falls from the sun onto our bodies. Contrary, our bodies synthesize it with the help of UV-B radiation and Cholesterol.
• Sun-screens provide us protection from the Sun. It hinders the absorption and synthesis of Vitamin D, thus creating more problems. 
• Sunlight gives you skin cancer. It does not unless you roast your skin under the sun. 
• A fatty liver has no effect on Vitamin D. It would inhibit/prevent the conversion and activation of Vitamin D. 
• Stress has no link to Vitamin D. High cortisol coming from chronic stress is known to inhibit Vitamin D synthesis. 
• People exposing themselves to early morning sun get enough Vitamin D. NO! Early risers expose themselves to UV-A radiation which is harmful to the human body. Expose yourself to the midday or an hour before or after midday to absorb maximum UV-B radiation. 
•  Our body would continuously produce Vitamin D under sun. It will buffer the amount required by your body and then stop immediately. 
• Everyone can absorb Vitamin D equally. Thin people absorb Vitamin D more efficiently as compared to obese people.
• Skin tone does not matter in Vitamin D absorption. Dark skinned people need 5 times the amount of Vitamin D as compared to light skinned people chiefly due to the higher melanin production in their skin.

I hope you guys understood everything I touched upon. I would expect you all to understand the relationship of Vitamin D with our immunity and apply this study to counter the current crisis we are facing with COVID-19 as well as to maintain health overall.

Stay safe and stay strong!

Warm Regards,

Mayur D. Chauhan