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.

Some studies have demonstrated a link between Vitamin D deficiency and poor asthma control. Vitamin D has been shown to have an immune modulatory role and plays a role in improving the response to corticosteroids which are the mainstay of treatment in persistent asthma.

A randomized double-blind placebo controlled study will be performed to assess whether vitamin D supplementation will improve control in South African children with persistent asthma at an academic hospital.

The researchers intend to enroll 100 children between the ages of 6 to 12 years with persistent asthma on inhaled therapy. The children will be enrolled from the pediatric outpatient department of Dr George Mukhari Academic Hospital, which is in Pretoria, South Africa. After enrolment, the children will be randomized into one of two groups; one group of 50 children will be given 1200 IU of vitamin and the other group of 50 will receive a placebo. 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 following groups of children will be excluded: children with intermittent asthma symptoms; children whose caregivers refuse to give signed informed consent; children who are not able to use a peak expiratory flow meter and those with concomitant chronic respiratory and/or cardiac conditions.

The vitamin D or placebo will be given in the morning daily to each child for six months. The date when the child was first diagnosed as having asthma will be noted, as well as the date of asthma treatment initiation, and the current treatment at enrolment will be recorded. The children will be asked to come to the hospital for follow up at monthly intervals. At these monthly visits, the children will be evaluated for signs and symptoms of poor asthma control by the study physician. The heights and weights of the children will be measured 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. Treatment adherence will be assessed by counting the pills in the containers by the study physician at the monthly visits. All enrolled children will be required to produce their tablet containers for pill counting.

Data will be analyzed using the IBM SPSS Statistics program. Analysis of variance will be performed in order to compare the difference in ATAQ scores and peak flow meter reading from baseline to six months post intervention between the two groups (vitamin D and placebo).

Inclusion Criteria:

- Children aged 6 to 12 years with persistent asthma on inhaled therapy, attending the pediatric outpatient department at Dr George Mukhari Academic Hospital in Pretoria, South Africa.

Exclusion Criteria:

- Children with intermittent asthma; Children whose caregivers refuse to give signed informed consent; Children who are not able to use a peak expiratory flow meter and those with a concomitant chronic respiratory and/or cardiac condition