A recent study has found that low vitamin D status was significantly associated with increased frequency of recurrent respiratory infections (RRI) and chronic cough among children.
Chronic cough refers to a cough lasting more than four weeks. An estimated 22% of all children experience chronic cough. Chronic cough may develop due to various causes, such as persistent bacterial bronchitis, upper respiratory tract infections, asthma or gastroesophageal reflux disease.
Vitamin D status plays a vital role in the immune system by regulating the activity of various immune cells. It reduces levels of inflammatory proteins while also increasing production of antimicrobial defensins. This combination of functions has led researchers to assess the role vitamin D plays in various immune related conditions, one of which being respiratory tract infections.
Studies have found that maintaining a healthy vitamin D status not only relates to a decreased risk for respiratory infections, but also reduced discomfort in those with recurrent respiratory infections.
Recently, researchers conducted a study in children to further evaluate the association between respiratory infections and vitamin D status in addition to determining the relationship between vitamin D status and chronic cough. They compared vitamin D levels between 101 children with chronic cough, 98 children with RRI and 124 healthy children.
The researchers wanted to know whether the children who experienced chronic cough and RRI had significantly lower vitamin D status than healthy children. Here is what they found:
- Average vitamin D levels were 11.96 ng/ml and 13.76 ng/ml in children with RRI and chronic cough, respectively. These levels were significantly lower than the average vitamin D status among healthy children, which was 31.91 ng/ml (p < 0.05).
- Vitamin D deficiency (< 15 ng/ml) was associated with increased frequency of RRI and chronic cough.
The researchers concluded,
“In this study, 25(OH)D levels were found to be lower in RRI and chronic cough groups compared to the control group.”
They continued to state the implications of this study,
“Co-administration of supplementary 5000 IU/day vitamin D for 3 months together with conventional treatments may be appropriate in the prophylaxis of RRI and chronic cough. The simple intervention of vitamin D supplementation appears promising in helping to prevent infections and chronic cough in children.”
The study brought interesting findings, but it’s important to remember that the study shows that low vitamin D correlates with RRI and chronic cough; it does not show that low vitamin D causes RRI and chronic cough.
Tovey, A. & Cannell, JJ. Vitamin D status may relate to chronic cough among children. The Vitamin D Council Blog & Newsletter, March, 2016.