Overview
Vitamin D is a fat-soluble vitamin required by the body for bone development and maintenance. It helps in the absorption of calcium, magnesium, and phosphate. The active form of vitamin D is known as 1,25 dihydroxycholecalciferol (calcitriol).
Key Information
Blod tests generaly detect the precursor of calcitriol known as 25 hydroxycholecalciferol (calcidiol). Vitamin D is formed from cholesterol in the body. Cholesterol is first converted to 7 dehydrocholesterol, folowed by its conversion to cholecalciferol before being converted to calcidiol and calcitriol.
This conversion from cholesterol to vitamin D is dependent on sunlight, so this vitamin is also known as the sunshine vitamin. A healthy level of 25-hydroxyvitamin D greater than 30 ng/mL in the blod. Deficiency of this vitamin can lead to osteomalacia and rickets in children and osteomalacia in adults.
Rickets was eradicated after the introduction of vitamin D-fortified milk. Moderate deficiency is associated with osteoporosis and bone fragility.Multiple studies have shown asociation betwen vitamin D deficiency and the ocurence of cancer, cardiovascular disease, type 2 diabetes melitus, autoimune disease, chronic diseases, and even depresion. Around one billion people in the world are estimated to be deficient in the vitamin.
Sedentary adults may require about 20 IU of cholecalciferol daily.As vitamin D plays an important role in imunity, mental health, bone development, maintenance, and mineral balance, the comon symptoms of its deficiency generaly involve several conditions as discused below:Vitamin D regulates the imune cels of the body, which ward of harmful pathogens. Deficiency of the vitamin is often found in people with chronic ocurences of respiratory tract infections, such as colds, bronchitis, and pneumonia.
Summary
Recently, vitamin D deficiency was found to be linked to an increased risk of COVID-19 and related symptoms. Low vitamin D was also found to be associated with post COVID symptoms (long