Effect of Vitamin D Supplementation on the Control of Asthma in Children at a South African Academic Hospital

The aim of this randomized double-blind placebo controlled study is to assess whether vitamin D supplementation will improve control in South African children with persistent asthma at an academic hospital. The following hypotheses will be tested: Vitamin D significantly and directly correlates with poor control of persistent asthma; Daily vitamin D supplementation for six months will result in improved control of persistent asthma compared to a placebo. It is intended to enroll 100 children between the ages of 6 to 12 years with persistent asthma on inhaled therapy. The sample size calculations are based on the hypothesis that vitamin D supplementation will result in a 25% improvement in asthma symptoms as measured by the Asthma Treatment Assessment Questionnaire (ATAQ) and peak flow readings. The children will be randomized into one of two groups; one group will be given 1200 IU of vitamin and the other a placebo. The vitamin D or placebo will be given in the morning daily to each child for six months. The children will be assessed monthly by the study physician, to evaluate for signs of poor asthma control e.g. persistent cough and recurrent wheezing. The heights and weights and peak expiratory flow meter readings will also be obtained monthly for six months. Blood samples will be taken for Vitamin D levels, calcium, phosphorus levels at baseline, third month and at the end of the study. All enrolled children will be required to produce their tablet containers for pill counting on a monthly basis to ensure adherence.