We all know that vitamin D is a fat-soluble vitamin and it is essential to our body. But do you know, Vitamin D is quite different from other vitamins due to certain specific roles. Because Vitamin D can be synthesized in the body itself when exposed to enough sunlight. Vitamin D consists of two major compounds, Vitamin D2 and Vitamin D3. Vitamin D3 is formed from 7-dehydro cholesterol when the skin is exposed to sunlight. While Vitamin D2 comes from plant sources and enters the body through diet. Vitamin D has many other roles too. Let’s have a look…
Vitamin D as a “Steroid hormone”
Calcitriol is the active form of Vitamin D. And this Calcitriol functions as a steroid hormone and it binds to a nuclear receptor protein and forms a “Calcitriol-receptor complex”. This complex enhances the gene coding and transcription and increases the amount of calcium-binding protein in the cell. It also has an important role in regulating calcium and phosphorus level in the body and mineralization of bone.
Vitamin D and Regulation of Blood Pressure
The renin-angiotensin system has an important role in the regulation of blood pressure. Renin is secreted by a juxtaglomerular cell in the kidney in response to decreased renal blood flow. It converts plasma angiotensinogen to angiotensin I and then into angiotensin II. It increases water and sodium reabsorption in the kidney and narrowing of the blood vessels. Evidence suggests that vitamin D regulates the renin-angiotensin system. There is an inverse relationship between blood pressure and serum 25(OH)D (form of vitamin D) levels and has been documented in several studies. When compared with vitamin D deficient individuals, they tend to have higher plasma angiotensin II levels and higher plasma renin activity. Vitamin D also prevents Diabetes mellitus, Kidney diseases, Cardiovascular Diseases and, Arthritis diseases.
Covid 19 and Vitamin D
Evidence supports the importance of vitamin D in the regulation of the immune system, indicating that it plays a critical role in viral infections. Vitamin D supplementation can reduce the risk of serious COVID-19 complications and mortality. Vitamin D can prevent cytokine storms by boosting the innate immunity that challenges the rapid response to the viral attack and avoiding the exaggeration of adaptive immunity. Several studies have proved the role of vitamin D in reducing the risk of acute viral respiratory tract infections and pneumonia.
Vitamin D in Cancer, Psoriasis
Calcitriol inhibits cancer cell proliferation and growth. This also prevents the proliferation of keratinocytes (a cell found in the epidermis) that prevents psoriasis.
Vitamin D in large quantities can cause apparent toxicity in all vitamins. Toxicity is estimated to be more than 2000 IU of vitamin D intake. Although excessive exposure to sunlight can cause skin cancer. But it is less likely to be toxic. Dietary sources are also less likely to cause toxins. Mainly, excess coming from the supplements can cause vitamin D toxicity.