Vitamin D

 

What is Vitamin D?

    Is a fat-soluble nutrient, a secosteroid hormone that is widely recognized as a modular of calcium absorption and bone health and further regulates neuromuscular function, cellular differentiation, insulin secretion, and blood pressure.

Why is Vitamin D important?

Vitamin D also plays an important role in immune regulation through interactions between 1,25-dihydroxyvitamin D and vitamin D receptors (VDRs). VDRs are expressed on a variety of airway immune cells, where they function as classic nuclear steroid hormone receptors and ultimately regulate the transcription of numerous genes associated with inflammation and immunomodulation.27 Vitamin D also plays an important role in respiratory infection by facilitating Toll-like receptor signaling through increased synthesis of human cathelicidin antimicrobial peptide,28-30 which is cleaved to generate the active cationic peptide, LL-37.

Vitamin D also exerts direct effects on target cells independent of gene transcription and may therefore be of relevance to airway inflammatory disorders.

What are the causes of a person's vitamin D deficiency?

    Despite the large variety of food supplemented with vitamin D a large proportion of the adult population remains vitamin D deficient, perhaps due in part to inadequate sun exposure and the rising prevalence of obesity which can lead to decreased vitamin D bioavailability.

Which factors influence Vitamin D metabolism?

Vitamin D metabolism occurs in the skin several factors are thought to influence Vitamin D skin metabolism:

• age
• body fat
• the level of skin melanin
• latitude
• the amount and degree of sun exposure
• use of sunscreen products with UV protection

How much of vitamin D should be given to an adult patient with asthma?

  In adults, the recommended dietary intake for Vitamin D ranges from 600 to 800 IU daily.

In adults with allergic disease, 60,000 to 30,000 IU of Vitamin D 2 per day resulted in significant relief of asthma and hay fever symptoms in more than 96% of patients suffering from asthma and seasonal allergies.

    

 Sheena D. Brown, H. Hardic Calvert, Anne M. Fitzpatrick. Vitamin D and asthma.  Dermo Endocrinology (April, May, June, 2012) 4: 2, 137-145