Asthma is chronic inflammatory disorder of the airways that causes recurrent episodes of wheezing, breathlessness, chest tightness, and cough, particularly at night or in the early morning; associated with variable bronchoconstriction and airflow limitation. Over a period of time in countries with comparable levels as India, an increase of up to 3% over a period of 10 years is seen.  As per Global Asthma Network phase-1 study the overall prevalence (range) of symptoms in adults was 4.4% (0.9–29.0%) for asthma ever and 10% adolescent and children have asthma ever with considerable variation across different countries. The recent Global Burden of Disease (GBD, 1990–2019) estimated the total burden of asthma in India as 34.3 million, accounting for 13.09% of the global burden. It also attributed that there were 13.2 per thousand deaths due to asthma in India. Asthma accounted for 27.9% of disability-adjusted life years (DALYs) in the Indian population.

Acute exacerbation of asthma is an emergency condition. It is defined as acute or subacute worsening of symptoms and lung function compared with the patient’s normal status and requiring a change in treatment or hospitalisation. The mainstay treatment for acute asthma includes inhaled beta2 agonists, ipratropium bromide and inhaled or systemic steroids, oxygen therapy, and need for hospitalizations. More than 50% of guidelines evaluated the need for reliever medication and lung function assessment (peak expiratory flow (PEF) or forced expiratory volume in 1 s (FEV1)) as tools for assessing asthma control.

Evidence suggests that patient with bronchial asthma who have vitamin D deficiency are associated with increased airway hyper-responsiveness, reduced pulmonary functions, poor asthma control, and reduce steroid responsiveness.

Active form of vitamin D (1- 25[OH]2D) is also critical in immune regulation, and deficiency of this vitamin has been linked to both autoimmune disease and cardiovascular disease. In addition, the vitamin D axis has been implicated in the pathogenesis of chronic respiratory diseases including asthma and chronic obstructive pulmonary disease (COPD). Vitamin D also act as immunomodulator and anti-inflammatory.

A study on pre-and postnatal VDD found that prenatal VDD caused diminished tracheal diameter, tracheal cartilage thickness and alveolar simplification which led to increased airway resistance.